Atmospheric Insights

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

There is also no change to the painful complexity, including the harsh reality that now is not a good time to be making weather predictions. Tropical convective forcing remains most intense across the Eastern Hemisphere. However, there are now arguably 2 regions, one centered in the Bay of Bengal (BB; including a tropical cyclone attempting to develop) and the other ~0/155E. The MJO component, as a continuation from the April event, is still propagating eastward ~10-12m/s leading to the west Pacific Ocean flare-up. The enhanced rainfall centered on the BB was left in the wake of the MJO, and is likely contributing to the onset of the regional-scale monsoon systems. All things considered, in addition to the possibility of the return of the nemesis of 2 convective regions discussed in the past, I am also concerned the quasi-stationary La-Nina tropical signal may be attempting a comeback. Again, the global financial markets are a great analogy. Just like we are still in a major bear stock market with economic issues will take some time to resolve, in terms of AAM the atmosphere still has significant bearish signals. Perhaps it is time to “short” the recent global AAM rally!

The combination of the winds and convective signals has led to a resurgent MJO signal in WH (2004) phase space, having ~1.5 sigma projection in octant 7 (through 22 May) and somewhat weaker in octant 6 retaining ENSO. The “loop scenario” offered in my 16 May discussion worked out. Phase 6 of the 250mb MJO snr psi composite anomaly plots best describes tropical and even a few extratropical circulation anomalies. My thought has been for this signal to persist in octants 6-8 for a while. However, there may start to be cancellation between the 2 regions mentioned above. Regardless of the projection, I still do expect a signal of tropical forcing to propagate through the Western Hemisphere during the next few weeks. Stay tuned as the mixed signals mess continues.

Tropical-extratropical interactions including the MJO and dynamical processes explained by the WB (2009) measure of the GWO have worked to create a recent respectable positive global wind tendency. Through 21 May global AAM tendency was ~plus 20 Hadleys having large zonal mean contributions from the equatorial and subtropical atmospheres. In fact, latest 250mb weekly means are ~3-4m/s. However, albeit shifted northward, 250mb weekly averaged zonal mean easterly wind flow anomalies are ~10m/s around 45-50N, strongly bearish.

Forced by AAM transports (see plots), those poleward and downward propagating anomalous zonal mean easterly wind flows have increased global and zonal mean mountain and frictional torques during the past 7-10 days. That has also contributed to the recent increase in global westerly wind flow with relative AAM near the R1 data climatology. The point from this untangling of the earth-atmosphere AAM budget is that there is finally a greater than 1 sigma projection of the GWO. Through 21 May the signal was in octant 4-5 of phase space. However, I am not at all confident there will be the nice GWO variations in the near future like observed during this past boreal cold season. There may be a weak orbit towards octants 7-8-1; however, hanging around toward phases 3-5 UFN appears probable (weak La-Nina). Phase 4 of the GWO 250mb snr psi composite anomaly plot reasonably describes the current global atmosphere.

Synoptic responses during the past week or so included the zonal mean storm track shifted anomalously poleward over the Northern Hemisphere, continuation of anomalous extratropical ridges (both hemispheres) with low pressure across the subtropics, and Western Hemisphere subtropical jets. Cutting to the chase, I do expect the latter to shift poleward and bring the Northern Hemisphere storm track southward (including the lower 48 states) over the next 2-3 weeks. During roughly days 10-20 a couple of strong progressive troughs across the western into the central states (north of ~35-40 degrees) is still possible should there be some form of GWO 7-8-1 transition. Maybe there is still some hope for project VORTEX!

I am continuing the notion I have had since mid-April about the average synoptic pattern across the USA during JJA. This is as depicted by roughly a superposition of GWO/MJO phases 3-5 (weak La-Nina atmosphere) of the 250mb snr psi composite anomaly plots centered on 15 July. As previously typed, that is suggestive of ridges near both coasts with some form of a trough in the middle of the country ~85-90W. Of course, a bit more global westerly wind flow and this pattern could be the reverse! Weather impacts, nationally and internationally should be understood from the composites.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We are working HARD to mainstream this effort. The support is very much appreciated!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a complete subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes Rex the Rottweiler VERY angry! I will not be able to do a complete discussion until the weekend of 5-7 June. Anyway, I need a break from all this atmospheric madness!

Ed Berry

When Will El-Viejo go back to Hell???

2009-05-16T14:47:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Very intense tropical convection has substantially cooled total and anomalous SSTs ~1-2C across the equatorial and North Indian Ocean during the past week. Consistent with the seasonal cycle, the 29-30C isotherm has expanded north into much of the Arabian Sea and Bay of Bengal. Interactions with the extratropics have forced well below normal waters centered on the South China Sea (SCS) and the Philippines. SST anomaly magnitudes across the SCS are ~minus 2C with totals less than 28C, not good news for regional monsoon onset.

Finally, for the first time in at least 2-3 years weak (less than 1C) positive anomalies extend all along the equatorial Pacific Ocean basin from ~140E to the coast of South America, with the 29C isotherm still west of the Dateline on the equator. Latest 5-day averaged TAO buoy data continues to show a less than average thermocline slope, and ~plus 1-3C anomalies at depth as a function of the latter. Is there an ENSO signal here especially given the recent stochastic Hell? Stay tuned, and see links below.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

There is no change to the weather-climate dynamical system involving mixed complicated signals. This is one reason for the relatively weak projections in both the WH (2004) MJO and WB (2009) GWO phase spaces (keeping in mind the details of these measures). Hence the confidence of any subseasonal and longer predictions must be inherently low.

Tropical convective forcing with the MJO did erupt across the Indian Ocean during the last 5-7 days. However, as I expected given the history of this event (see past discussions), the equatorial signal is propagating east very quickly, ~15-20m/s per my own “back of the envelope” calculations. Supportive of the latter is the projection onto convectively coupled Kelvin waves per coherent modes Hovmollers. Full disk satellite imagery suggests there is some consolidation occurring ~120E north of the equator. For reasons that I will only briefly discuss in the following, I think we may be looking at another behavior of tropical forcing having some similarities to this past March-April.

The atmospheric circulation has been drifting back toward La-Nina during the past couple of weeks ("over bought" atmosphere?), related to the tropical forcing but also involving GWO processes as defined in WB (2009). Total (not relative) AAM has dipped to ~1 sigma below the R1 data climatology (through 14 May), with significant contributions coming from the subtropical atmospheres of both hemispheres dominated by anomalous zonal mean easterly wind flows. In fact, latest weekly averages of these anomalous easterlies at 250mb have been greater than 5m/s. Furthermore, there is once again interhemispheric meridional symmetry of zonal mean zonal wind anomalies favoring strong midlatitude ridges. Even though the global signal is weak (competing terms in the AAM budget), phase 3 of the GWO 250mb psi composite anomaly plots reasonably depicts the current tropospheric circulation.

The astute readers will notice that the distribution of zonal mean relative AAM anomalies is similar to early-mid March, including the equatorial positive signal (cyclonic shear in the subtropics). There are also some similarities with the other terms, including the frictional torque and the transports (see plots). A notable difference to me is that there are no anomalous upper tropospheric subtropical troughs in the region of the Dateline. In fact, I could suggest that these troughs have been displaced into the east Pacific with anticyclones around the Dateline/west Pacific Ocean. In other words, the possibility exists that the ENSO background state in the tropics has been shifted east, perhaps as the result of the past 2 stochastically (GWO) driven MJOs. Interestingly, the Australian jet has been anomalously strong the past 1-2 weeks. Are we seeing a forcing-response-feedback loop, and is this the “hard reality” of ENSO transition, should that be the case?

Regardless, my point is I think it is probable the tropical forcing will get established ~0/140E during the next couple of weeks, then perhaps also continue east as a MJO into the Western Hemisphere. The WH (2004) MJO projection may do a “loop inside the magic 1-sigma circle of death”, then come out and "hang around" in octants 7-8 for a while. Remembering that the WB (2009) measure of the GWO is a global dynamical quantity tied to ENSO, its projection may remain relatively weak until the interannual component of the weather-climate system clarifies.

The global circulation may behave as shown by phases 3-5 of the GWO 250mb psi composite anomaly plots during the next couple of weeks. Weeks 3-4 may see a loose GWO/MJO superposition of phases 6-8. At some point during early-mid June a form of at least GWO 7-8-1 transition may be probable. Until we can show maps having several variables with verifiable probabilities, this forecast information will continue to be confusing to many users.

For the USA, with variations that suggests troughs off/around the west coast and the region of the eastern states, with anomalous ridging west of the Mississippi River the rest of this month. Anomalous low pressure in the Gulf of Mexico including the possibility of a hybrid tropical cyclone (Anna?; SSTs are marginal, refer to official forecasts) combined with the above may give the Plains some respite from severe local storms at times. During the first couple weeks of June strong progressive troughs may again shift into the western and central states poleward of ~35-40N. That may (again, very low confidence) lead to the situation I discussed in my 9 May posting.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We are working to mainstream this effort. The support is very much appreciated!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a complete subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes Rex the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 22-24 May.

Ed Berry

Time to Punt our Stochastic Football!!!

2009-05-09T15:14:00.000-07:00

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

While the general behavior of our weather-climate situation continues to evolve as expected during the past several weeks, many details have become more complicated than I would like. I do think I see “what is going on”; however, I have typed that before and drawn the wrath of Rex the Rottweiler! Somewhat analogous to rolling a backup bowling ball and relying on that to get a Brooklyn strike, I feel my poor USA assessment a week ago for this upcoming week (western USA trough for a period of days) was partly linked to “playing the MJO card” while not being conscientious enough about its initiation. That is, stochastic GWO dynamics forced its initiation during early-mid March around Indonesia (see past discussions), and that forcing appears to have been “taketh away”. This once again demonstrates to me and should also to the rest of the world that it is important to keep in mind the on-going dynamics, and to know better than “play a signal” regardless of its origins (for example). The latter are serious basic research issues, and there is no way I can do justice about those matters here.

WH (2004) plots updated through 7 May show a greater than 1 sigma projection in octant 7 (west Pacific Ocean) of phase space, having done a loop from a week ago. I was expecting phase 8 then 1. In reality, there is no “loop” in the atmosphere. The trace is an artifact of this empirical technique. Animations of upper tropospheric daily mean vector wind anomalies show a well-defined subtropical wave train (SWT) propagating through the Eastern Hemisphere ~30N forced by interactions with the extratropics (sound familiar?). That has disrupted the MJO signal, and the dynamics do involve the WB (2009) measure of the GWO. For example, tied to the SWT (a zonally oriented RWD typical of a GWO response), anomalous upper tropospheric twin anticyclones are returning to Africa and the western Indian Ocean. In other words, and consistent with the past 2008-09 boreal cold season, I offer that the GWO is again driving the MJO. It is clear to me that the extratropics are currently forcing the tropics. Could this kind of behavior be telling us something about where ENSO is going?

Full disk satellite imagery and other tools show that the global signal of tropical convective forcing is somewhat disorganized. However, cutting to the chase, the African Highlands/Gulf of Guinea regions are active, there is Indian Ocean “sputtering” and a convectively coupled Rossby mode is over western Indonesia. It is probable there will be some form of consolidation over much of the Indian Ocean during the next 1-2 weeks. The west Pacific Ocean (loosely) is also somewhat active, and that region may again become a “wild card” UFN (recall our "nemesis"). During weeks 2-3, enhanced rainfall should further consolidate/shift into the region of Indonesia, and the Eastern Hemisphere monsoon systems may also be active at that time. It is uncertain whether or not a “REAL” MJO will initiate during the next several weeks.

As expected, the GWO projection in phase space is improving located in octants 8-1 through 7 May. It is at this point where I can only “hope” readers can start to put things together (need maps!). Tied to the SWT interacting with the MJO signal, etc., a strong negative global friction-clustered mountain torque index cycle is in progress as I type. The latter is contributing to a decent negative global AAM tendency (~20 Hadleys relative to R1 data climatology) with much of the zonal mean contribution coming from the subtropical atmospheres. Stated another way, several circulation features characteristic of La-Nina are returning. A response is that our strong North Pacific Ocean jet is collapsing, one of the reasons all numerical models have been performing poorly (along with me!) for about the past week. Other behaviors include above average easterly wind flows increasing ~25-30N/35S, zonal mean storm tracks shifting anomalously poleward at least across the Northern Hemisphere, and ridges starting to dominate the extratropics.

Summing up so far, could our “May surprise” be a re-emergence of stationary tropical forcing across the Eastern Hemisphere favoring an eventual return to La-Nina? Or, will we finally see the initiation of decent coherent MJOs that could significantly impact the equatorial Pacific? These are only 2 of an infinite number monitoring issues, and stay tuned. I wanted to make a bit of an effort to get readers to gain an even better appreciation of some of the serious real-time scientific matters that are currently (and always) involved spanning wide time and space scales. This is an example of the next level of weather-climate research/monitoring that is needed, and hopefully that will come to fruition via the ESRL/PSD GSDM web page.

As I typed last week, a GWO/MJO 8-1-2 transition is in progress (WH “loop” understood). The 250mb GWO snr psi composite anomaly plot for phase 1 reasonably depicts the current global circulation. One can also argue a loose superposition of MJO phases 1-2 with GWO phase 1. Per above, with reasonable confidence (I hope!), I offer that a superposition of phases 2-3 for both the GWO and MJO 250mb snr plots for psi and other variables is plausible through at least week-2. For the USA, this suggests our familiar synoptic pattern of progressive western and central states troughs increasing the risk of severe local storms across the central and northern Plains/Upper Mississippi Valley. Possible weather globally can also be inferred from the composites, in addition to the expertise of the international centers. There has been some recent increase of global high impact weather.

Afterward, and I think some readers will understand why, I do have some concern (low confidence) that heading into June, with perhaps many episodes through August, that a synoptic pattern typical of ~GWO phase 4 may occur. That is, per 250mb snr psi composite anomaly plots centered ~15 July, USA west and east coast ridges with troughs across the central states into the Great Lakes at times are possible. While there may be periods of cool and wet for the Plains and Great Lakes states, episodes of intense heat may occur particularly west of the Continental Divide.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We are working to mainstream this effort. The support is very much appreciated!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a complete subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes Rex the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 15-17 May.

Ed Berry

Atmospheric MAYhem???

2009-05-02T15:13:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. Partially linked to the seasonal cycle, the warmest SSTs globally are across the equatorial Indian Ocean, with totals in excess of 30C and anomalies ~plus 1-2C. Exceptionally strong convective suppression during at least the past couple of weeks has also contributed to these warm waters. SST anomalies across all Nino regions are loosely slightly positive. Recent surface westerly wind anomalies have assisted with this warming. However, the 29C isotherm is still west of the Dateline on the equator. Regardless of whatever viewpoint anyone chooses, scientifically, the future course of ENSO (global ocean-land-atmosphere dynamical system perspective) is unclear. Historically, weather-climate events (surprises?) during May can provide some insight.

http://www.wmo.int/pages/prog/wcp/wcasp

/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

Per WH (2004) measure and other tools, the moist convective signal with the ongoing strong MJO is propagating through the Western Hemisphere as I type. Updated through 1 May there is still well over a 2 sigma projection in octant 7 of WH (2004) phase space. Broadly, during the last couple of weeks numerical models have tended to weaken this signal too quickly and have been too slow with the eastward propagation. A large contribution to the MJO projection has been the Indian Ocean suppression mentioned above.

Moist tropical convective forcing has already propagated poleward off the equator across the west central Pacific, increasing the tropical cyclone hazard in the region of the Philippines. The accompanying surface westerly wind flow anomalies are also shifting away from the equator into the both hemispheres along and west of the Dateline. Meanwhile, moist convection is increasing from Central and South America into equatorial Africa. There is some “sputtering” along the east Pacific Ocean ITCZ, and working with the extratropics, a relatively moist subtropical jet (STJ) is directed toward the southern USA states assisting with rainfall production. The latter is consistent with phase 7 of the MJO, which is an EL-Nino like circulation response per WB (2009) GWO phase space. However, cutting to the chase, there are still non-trivial La-Nina characteristics to the global circulation, and the above mentioned STJ is rather “pathetic”.

There continues to be the lack of a significant projection in phase space of the WB (2009) measure of the GWO (since ~1 April). Recall (again) that the GWO is a global dynamical measure of the atmosphere, whereas the WH (2004) empirical MJO measure only considers lower and upper tropospheric winds with OLR anomalies within 15 degrees of the equator. From the global perspective, there has been a weakening La-Nina allowing relative AAM to return to about normal per R1 data climatology. In fact, through 30 April relative tropospheric AAM is slightly above normal. Additionally, AAM tendencies have not been large (for reasons), all combining to give the appearance of a weak GWO signal.

However, zonal mean and regional scale GWO components, as well as individual terms of the earth-atmosphere AAM budget have been anything but weak. These include Eastern Hemisphere subtropical wave trains that excited the 2 (stochastically forced "cheap") MJOs in the region of Indonesia during the past 4-5 months, and roughly 20-30 day variations of the global mountain torque. Through 30 April the global frictional torque has dipped to below minus 10 Hadleys largely from frictional dissipation of recently added westerly wind flow. That is the lowest since about mid-January. The frictional dissipation has not only occurred in portions of the tropics/subtropics (tied to the MJO), but also across the extratropical storm track regions. My suspicion is there may be a large negative AAM tendency during the next couple of weeks (more said below). Is it time to “short the atmosphere”?

Regardless of details, a superposition of phase 7 for both the GWO and MJO snr 250mb psi composite anomaly plots best depicts the current global circulation. For example, there has been subtropical transition of Eastern Hemisphere upper tropospheric circulation anomalies, and a “poor excuse” of an extended north Pacific Ocean jet has occurred. These behaviors were expected per past discussions.

It is relatively clear to me that a GWO/MJO 7-8-1-2 transition is in progress (a.k.a. a low to high zonal eddy wave number transition response across the Northern Hemisphere extratropics). The corresponding snr 250mb psi composite anomaly plots should depict the expected synoptic behavior of the atmospheric circulation over the next few weeks. The probable response for other variables such as anomalous 2m air temperature across North America can also be determined from the composites (we hope to add more variables). This evolution should go through its life cycle by roughly later week-2/week-3. Numerical models already have been, and will continue to struggle (in addition to seasonal transition issues).

Enhanced moist tropical convective forcing is likely to return to the Eastern Hemisphere including the Indian Ocean/Indonesian regions during weeks 2-3. However, uncertainty issues include persistence, and whether or not the MJO signal will continue. In any case, it is during this period that AAM tendency may become strongly negative contributing to a strengthening projection of the GWO perhaps in octants 2-3 (back toward La-Nina) of phase space by week-3. Disciplined serious daily weather-climate (WB (2007) GSDM sense) monitoring is critical UFN to gain a better understanding of the course of any additional subseasonal activity and possible ENSO ramifications. Using models as a stand alone is anything but scientifically complete and defensible. Synoptically for the USA, other than being about a week later, there is little change from what I typed in my 24 April posting.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We are working to mainstream this effort. The support is very much appreciated!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a complete subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes Rex the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 8-10 May.

Ed Berry

“Stochastic Forcing Giveth Subtropical Westerly Flow, Then???”

2009-04-24T14:16:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. There is little change in the spatial patterns from a week ago. The largest negative global tropical SST anomalies appear to be across the North Atlantic Ocean with magnitudes approaching 3C west of Africa. With varying amplitude, the latter have been persistent for at least the past 2-3 months. Slow warming of the convectively suppressed Indian Ocean continues, with totals approaching 30C.

Nino SSTs are generally near normal. Does this suggest La-Nina is “over”??? When thinking about this, please remember that ENSO is a global phenomenon involving the ocean-land-atmosphere dynamical system. ONI simply does not cut it!

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

As has been the case during much of this past boreal 2008-09 cold season that I will remember as the “La-Nina from Hell”, weather-climate signals are once again conflicting and incredibly complicated. From intense daily monitoring and on-going work to better understand the scientific issues, my comfort level is okay with all this. However, this medium of communication is very inefficient, stressing the importance of brevity. The astute and learned readers will see matters intentionally not discussed.

Not surprisingly, the moist tropical convective forcing with our strong MJO, ~2.5 sigma projection in octant 5 of WH (2004) phase space retaining ENSO, has significantly slowed its eastward propagation. This is consistent with late January and mid-March, the former (latter) after (before) initiation. Full-disk satellite imagery shows the moist convective MJO signal centered ~0/150E extending from near the Philippines into the South Pacific Ocean. Unquestionably and with at least a two-week forecast lead time (see 11 April discussion, for example), this MJO working with extratropical dynamical processes has been impacting the USA. For instance, Rossby wave energy dispersions (RWDs) from the Eastern Hemisphere upper tropospheric anomalous twin anticyclones has contributed to the current digging western USA trough, and there is a subtropical jet across the southern states. A loose superposition of the 250mb snr psi composite anomaly plots for phase 2 of the WB (2009) measure of the GWO and phase 5 for the WH (2004) MJO depicts the ongoing global circulation.

There continues to be little projection in WB (2009) GWO phase space. However, fast time scale processes such as the RWDs discussed above are a component of the GWO. In fact, 250mb circulation wind anomalies have been ~30-50m/s with these features. The weak projection is one ramification of the GWO being a global dynamical circulation measure, and that itself may be a quantification of conflicting weather-climate signals (in this case). However, excursions understood, there has been a clear shift of the GWO along the La-Nina attractor “upward” in phase space. That is, there have been stochastic dynamical processes working to add westerly wind flows to the subtropical atmospheres. This movement has been displaced toward octants 3-5 of GWO phase space, suggestive of a weakening La-Nina.

Updated through 22 April, tropospheric global relative AAM has spiked too slightly above the R1 data climatology. Above normal AAM has not been observed since at least early December 2008. I do think some additional increase is possible in the near term. The punch line is that we are not out of the “bear atmosphere” yet, analogous to the financial markets. Sparing details, there is already subtle evidence our La-Nina base state is attempting to reload. For example, with symmetry anomalous ridges dominate the extratropics of both hemispheres, characteristic of the all too familiar positive phase of the Branstator (2002) circumglobal teleconnection.

Per Wolter (personal communication), La-Nina impacts tend to be less severe during April. Just as stochastic (GWO) forcing gave us the on-going (cheap but strong) MJO which has contributed to the “blessed precipitation” across many previously dry areas across the country, the subtropical westerly wind flow anomalies may be “taken away”. I will be carefully monitoring all aspects of the global and zonal mean terms of the earth-atmosphere AAM budget UFN (components of the GWO). Stay tuned.

In the meantime, during weeks 1 and 2 tropical forcing should become well established across the Western Hemisphere, only to propagate back into what may be a very warm Indian Ocean by roughly weeks 3-4. For simplicity, the superposition of the snr plots discussed above is okay through roughly days 5-7. I think the notion of a 7-8-1-2 transition depicted by both the GWO and MJO 250mb snr psi (and other variables) composite anomaly plots is still the best forecast solution for ~weeks 2-3. During mid-late May the global circulation may be represented by superposition of GWO phases 2-3 with MJO phases 4-5 should Eastern Hemisphere tropical convective forcing intensify.

For the USA, after the week-1 western trough, an extended north Pacific Ocean jet/split flow pattern of western troughs, closed cyclones/downstream southeast states ridge scenario is reasonable ~weeks 2-3 (already offered previously). The latter will be shifting slowly north with the seasonal cycle. Mid-late May heading into June could see a resumption of more full-latitude progressive western and central states troughs, focusing the emphasis for anomalous precipitation and severe local storms across the Northern Plains and Upper Mississippi Valley. Other weather impacts, nationally and internationally, should be understood.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We are working to mainstream this effort. The support is very much appreciated!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes Rex the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 1-3 May.

Ed Berry

“Stochastic MJO” Hard Times/AAM Rally “for Real???”

2009-04-17T13:52:00.000-07:00

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 24-26 April.

Ed Berry

Strong MJO and Transitioning Toward ENSO Neutral: End of Story – Correct???

2009-04-11T14:42:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. Very warm SSTs continue across the Indian Ocean into the southwest Pacific, with totals ~29-30C and anomalies roughly plus 1C. However, the recent increase of intense to severe tropical convection in the area of 60-110E slightly north of the equator has started to cool the ocean waters in that region.

Flanked by weak warm anomalies ~plus 0.5C, similarly cool SSTs are present around 140-170W across the equatorial Pacific. Totals have warmed to ~26-28C over much of Nino 3 region; however, the 29C isotherm is still well to the west ~165E on the equator. Substantial warmth is still present at depth along the equatorial thermocline west of 160W at ~100-200m per latest 5-day averaged TAO buoy data. Magnitudes are around plus 2-4C.

Worth repeating from a week ago, only a few scientific matters can be discussed in this forum. Several very serious weather-climate monitoring issues exist that careful attention must be paid to heading into boreal summer. These include warming of the west Pacific Ocean should westerly wind bursts start to occur on the equator, while atmospheric dynamical processes stubbornly try to maintain La-Nina. It is also important to keep in mind “the fundamentals,” and not get caught up in overly simplified “cookbook measures” such as univariate ENSO indices (ex., the ONI) as well as those involving the MJO. In the following, I am again challenged to write about complicated and somewhat conflicting signals.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

The most robust subseasonal signal continues to be the (pseudo) MJO. Per WH (2004) technique, through 10 April ~2.5 sigma projection in octant 2 of phase space was observed, approaching 3 standard deviations emerging into octant 3 retaining the ENSO signal (more realistic; constructively interfering with La-Nina). Full disk satellite imagery shows intense tropical forcing centered ~5N/90E, and subtropical transition to upper tropospheric twin Indian Ocean (west Pacific Ocean) anomalous anticyclones (cyclones) is occurring as I type. Furthermore, zonal mean upper tropospheric anomalous easterly wind flow is returning to the deep tropics (~5m/s at 250mb). More said below.

Sparing other details about what appears to be a real “text book” MJO, the reader may ask, “why am I complaining about it?” As was discussed in my 4 April posting, driven by stochastic dynamical processes explained by the WB (2009) measure of the GWO, this MJO grew out of the noise in the region of Indonesia. Furthermore, to state that there are similarities involving this event with the rogue MJO during late December 2008-January 2009 is anything but scientifically defensible in terms of complete understanding.

My point is that I am confident the area of enhanced tropical rainfall centered west of Indonesia is unlikely to coherently propagate eastward into the central Pacific Ocean on the MJO time scale. I do think the latter will contribute to reinvigorating our on-going quasi-stationary La-Nina base state (subseasonal time scale), and if there is an eastward shift, that may occur abruptly per GWO OLRA composites. Finally, I also feel that just as this MJO signal grew out of the noise in the region of Indonesia during mid-late March, it is also probable to decay in that region during the next few weeks. Yes, the Rottweiler has been licking his chops during this “MJO situation” the last few weeks!

As suggested above, our La-Nina base state is “reloading”, at least in terms of the zonal mean and the return of the expected asymmetric zonal wave number 1 pattern of tropical circulation anomalies. For instance, persistent anomalous easterly wind flows through out the global subtropical atmospheres (near 15-20S and 25-30N) is beginning to shift equatorward linking up with the deep tropical anomalous easterlies. Phase 3 of the MJO ~250mb snr psi composite anomaly plot reasonably depicts current tropical circulation anomalies. Global relative AAM, updated through 8 April, has been hovering ~1 sigma below the R1 data climatology. Holding it up, so to type, has been yet another one of those complicated feedbacks having details impossible to write about here.

Global relative AAM tendency has spiked to ~plus 20 Hadleys, forcing the WB (2009) measure of the GWO toward octant 4 of phase space while shifted toward the La-Nina attractor. Carefully studying various animations suggests that it is reasonable to submit that what was first a strong positive East Asian ~20 March then global mountain torque ~1 April had a contribution from the past southwest Pacific tropical forcing. Working with other extratropical processes, the linkage was established via Rossby wave energy dispersions (RWDs) from the south Pacific forcing. These were phased properly to favor anomalously high mean sea level pressures on the eastern sides of major mountain massifs including East Asia and the Andes.

A synoptic response for the USA was initially an active southward shifted storm track late March and then more recently split flow expanding into the western states from the Pacific Ocean. The latter has helped to maintain the active southern branch of the westerlies, bringing much needed precipitation to areas experiencing severe drought. Sparing details (again), the more sophisticated readers will see there is even a weak signature of the split flow from the AAM transports plot. I do think this situation is about to end.

Broadly, where do we go from here? My feeling is that the tropics and extratropics will start to sync up better during the next few weeks, meaning that global AAM tendency is likely to become negative “soon” as both surface torques may contribute. I also feel there will be lingering La-Nina circulation anomalies, particularly in the zonal mean, well into boreal summer. Anomalously strong zonal mean easterly wind flows across the Southern Hemisphere subtropical atmosphere this upcoming austral winter may provide a clue of what to expect for the Northern Hemisphere 2009-10 cold season.

Repeating one of my standard excuses, any subseasonal outlook this time of year has higher uncertainty, and our current situation is adding to it. That typed, my offering that the ~250mb psi snr composite anomaly plots for GWO phases 4-5 for week-1 last weekend worked out okay. Per above, there has been extension of the jet across the north Pacific Ocean but poleward shifted in our La-Nina situation, leading to the current USA split flow. During week-1 phase 1 of the GWO snr ~250mb psi (and other variables) composite anomaly plot is likely to depict the global circulation. With somewhat high confidence, I think a superposition of anomalies shown by phases 4-5 of MJO ~250mb psi snr composite anomaly plots (representing the quasi-stationary La-Nina) with phases 2-3 of the GWO are probable during weeks 2-4 (timing may be golden; however, it is in the noise after week-1!).

Synoptically for the USA, and most numerical models are doing a reasonable job into days 5-7, another western states split flow closed low is likely next week. Afterward (roughly week-2), this split flow should consolidate while the “northern branch ridge” retrogrades. Hence there is likely to be a period of an east Pacific Ocean trough-western states ridge and so forth. Perhaps similar to many episodes during spring 2008, ~weeks 3-4 a resumption to strong but progressive western and central USA troughs may resume. Should we go back to that northward shifted but active storm track, drought may return/intensify across the southern USA once again. Speculating farther into summer, should this La-Nina situation linger and excursions into octants 4-5 of GWO phase space occur, like summer 2008, there may be episodes of anomalous heat contributing to elevated fire dangers across the western states.

Other weather ramifications, nationally and internationally, should be understood. For instance, more western USA “trough attacks” are likely to make the storm chasers happy across the Plains, and the concern for Bay of Bengal (and possibly Arabian Sea) tropical cyclogenesis may increase substantially during the next few weeks. On the latter, there are already 10-15m/s surface westerly wind flow anomalies along and north of the equator across the Indian Ocean.

Appendix

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 17-19 April.

Ed Berry

No Respect Given to “Cheap MJOs”; Is There Hope from this La-Nina Hell???

2009-04-04T14:23:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. For the first time perhaps in more than a year, the warmest SSTs globally during the past week have been centered in the equatorial and North Indian Ocean (~5-10N/60-90E). Totals have been in excess of 30C with anomalies generally greater than plus 1C. Persistent convective suppression (until recently; discussed below) and possibly the seasonal cycle are contributing. Anomalously warm SST “pockets” have also been developing northwest of Australia and eastern Indonesia. Intense-severe tropical convective forcing focused around 10-20S/180-160W has cooled the South Pacific Ocean.

Finally, recent weak surface westerly wind flow anomalies have continued to moderate the cool Nino SSTs. SST anomalies ~minus 0.5-1C are still hanging around 140-160W in the equatorial East Pacific, with even shallow positive anomalies of similar magnitude appearing west of South America. Substantial warmth is present at depth along the equatorial thermocline west of 160W at ~100-200m per latest 5-day averaged TAO buoy data. Magnitudes are around plus 2-4C.

While only a few scientific matters can be discussed in this forum, there are several very serious weather-climate monitoring issues that attention must be paid to heading into boreal summer. These include warming of the west Pacific Ocean should westerly wind bursts (WWBs) start to occur on the equator, while atmospheric dynamical processes stubbornly try to maintain La-Nina. In the following, I am again challenged to write about exceptionally complicated and somewhat conflicting signals.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

On face value, the strongest subseasonal atmospheric signal is the MJO. Through 3 April phase space plots employing the WH (2004) MJO measure show approximately a 2.5 sigma projection in octant 1. This is real; however, it was forced by extratropical dynamics including fast subtropical wave trains (SWT)/baroclinic wave packets (BWP) that are considered by the WB (2009) measure of the GWO. I do not want to get into details, especially when they are still in the realm of research. The point is that this MJO is a wind driven event (loosely), and perhaps analogous to a cheap non-mesocyclone EF-1 tornado that occurs when a low LCL shallow rain shower crosses a surface boundary embedded in intense shear. What are the average warning lead times for those? In any case, for forecasting purposes, it is appropriate to “play this MJO card”, for the time being.

Nevertheless, somewhat similar to December 2008, this dynamical tropical convective signal literally grew out of the noise (no SSW this time), and that is one reason why the MJO snr composite anomaly plots for 250mb psi do not accurately depict the current tropics and extratropics very well. In other words, non-oscillatory decay time scale processes (stochastic) explained by the WB (2009) measure of the GWO as opposed to truly quasi-oscillatory subseasonal tropical convective variability resulted in what the "rest of the world" now considers to be a MJO. Typically, MJOs originate around the African/Indian Ocean regions, compared to Indonesia as was observed early March 2009 and late December 2008. I submit those who take the time to understand these kinds of issues scientifically will have a better understanding of subseasonal matters/global atmospheric dynamics including making predictions (on average), than those who just use numerical model forecasts as a stand alone.

Full disk satellite imagery and other diagnostic tools clearly indicate that the strongest tropical convective forcing has been focused across the South Pacific Ocean (~15S/165W) for about the past week or so. Other tropical forcing has been occurring in the regions of tropical South America and equatorial Africa. This spatial pattern of approximately 3 centers of enhanced rainfall is a characteristic of a Western Hemisphere MJO signal.

Tying back into the monitoring issues, Hovmoller plots of OLRA have shown a slow eastward shift of tropical forcing across the southern tropics (2.5-15S) since roughly November 2008 from ~120E to 165W. The recently observed South Pacific Ocean forcing appears to be the most intense in at least a year. Broad brushing details, on interannual time scales, perhaps we are observing the most significant perturbation on what has been an extremely stubborn La-Nina base state. A respectable WWB did occur south of equator (~10m/s anomalies), and there have been a few tropical cyclone spin-ups (including Lin). Is this an indication that there will be a resumption of REAL MJOs (or coherently eastward shifting modes) leading to WWBs on the equator? Stay tuned. Perhaps we are starting to observe a forcing-response-feedback process involving the weather-climate dynamical system, and (state dependent multiplicative?) noise events leading to “cheap MJOs” during La-Nina are part of that.

Tropical convective forcing appears to be waning across the South Pacific, while slowly increasing across the warm Indian Ocean. In fact, tropical convection may be getting concentrated in the region of 90-120E. Most forecast tools do suggest convection to continue intensifying in this region during the next 2-3 weeks. Albeit shifted poleward (~35N/35S), zonal mean upper tropospheric easterly wind flow anomalies have been strengthening again, recently ~5m/s at 250mb. Global relative AAM has decreased to near 1.5 sigma below the R1 data climatology (through 1 April), and there is improving meridional symmetry of interhemispheric zonal mean zonal wind anomalies including the easterlies. Bottom line, our La-Nina base state is re-intensifying, at least for now.

On a more regional scale, and I do think this is a feedback from the South Pacific signal, while the global mountain torque is nearly zero, the East Asian component is strongly positive, ~plus 30 Hadleys. If updated today, I suspect the latter is already collapsing. That has contributed to a positive AAM tendency of ~plus 20 Hadleys forcing the WB (2009) measure of the GWO to orbit into octants 3-4 of phase space (shifted toward La-Nina). From various animations I can already see evidence that the EAJ will extend (shifted somewhat south) as a response leading to split flow across North America by week-2. Most models do show this. However, I also think this jet will collapse leading to initially “cutoff lows” across the Desert Southwest, followed by stronger and energetic baroclinically amplifying progressive full latitude western and central USA troughs. The latter may be probable late week-2 into week-3. The models are likely to struggle with the latter.

Overall, any subseasonal outlook this time of year has higher uncertainty. Our current situation is adding to it. That “excuse” typed, I think the GWO snr plots of 250mb psi (and other variables) composite anomalies for phases 4-5 week-1 then 7-8-1 week-2 are probable. Phases 2-3 may become more persistent weeks 3-4, possibly linearly superimposing upon the MJO snr composite anomaly plots of 250mb psi for phases 4-5 (in the WB (2007) GSDM sense). The latter is essentially La-Nina. Will that situation persist afterward? Stay tuned.

After a bit of a respite next week, much of the Rockies and Plains may experience exceptionally active weather again week-2, perhaps including precipitation opportunities for the southern High Plains. Should we go back to a northward shifted but energetic storm track starting week-3, drought may intensify across the southern USA once again. Other weather ramifications, nationally and internationally, should be understood.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We appreciate all the support!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. An early on-line release can be downloaded from the following link:

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 10-12 April.

Ed Berry

The GWO Giveth then Taketh Away?

2009-03-27T14:16:00.000-07:00

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

Sounding like the proverbial broken record during this 2008-09 La-Nina from Hell, the weather-climate situation is an extremely complicated mess, with lots of “tugs and pulls”. However, only from rigorous daily monitoring including evaluation of our “GWO-based diagnostic tools”, I do feel fairly comfortable with my interpretation. In the following, I again want to broad-brush, particularly since many readers are getting used to studying the budget terms of the on-line AAM plots, as well as the WB (2009) measure of the GWO.

Since October 2008, there have been “regular” ~25-30 day variations of the GWO, with each orbit spiraling toward the La-Nina attractor in phase space. This is a significant difference from the 2007-08 La-Nina, when slower subseasonal activity including MJOs occurred. Perhaps similar to the bear financial markets, the depths of El-Viejo were reached during late January and mid-late February. The latter were roughly 2-3 standard deviations below the R1 data climatology (the major SSW contributed; see past discussions), comparable to the strong “season of the witch” 2007-08 cold event. One direct response was for drought to intensify across many portions USA including the central and southern High Plains, while locations across the northern portion of country received significant to excessive precipitation.

Starting late February, dynamical processes explained by the GWO including meridional eddy momentum transports and the surface torques have worked hard to increase global westerly wind flow. Much of that contribution has been in the equatorial and Northern Hemisphere subtropical atmosphere, where upper tropospheric zonal mean westerly wind flow anomalies were ~5 m/s. Zonally oriented fast Rossby wave energy dispersions (RWDs)/subtropical baroclinic wave trains (SWT) involved with the GWO literally forced Indonesian convection into the anomalously warm southwest Pacific Ocean (SWP) by the middle of this month. I did not expect the latter (Rottweiler is very angry with me!). In any case, that was good news for many dry portions of the country.

The SWP forcing also did its part to add additional westerly wind flow to the global and various zonal mean bands of the atmosphere (including substantially decreasing intense subtropical zonal mean easterly wind flows). In fact, there was even a weak surface westerly wind event mostly south of equator having anomalies ~10m/s. Should this same type of behavior occur in May (for instance) across the west central Pacific Ocean on the equator, maybe this will be the start of an “exorcism”. Right now, in terms of the possibility of a warm event, I am not optimistic about that option. Through 24 March global relative AAM is only slightly below the R1 data climatology. Similar to what some may ask about the current bear market rally, is this AAM rally about to end?

Eastern Hemisphere tropical convective forcing has become incoherent. A “GWO-driven” MJO signal is moving through the Western Hemisphere. Just like that observed December 2008, this “MJO” evolved in the region of Indonesia, inconsistent with past documented work. That is why the WH (2004) measure of the MJO indicates ~1.5 sigma projection on octant 8 of phase space, updated through 26 March (ENSO removed). I do expect this signal to return to the Eastern Hemisphere during the next couple of weeks, and I think it is plausible to see some enhancement initially over the anomalously warm waters of the Indian Ocean (areas cited above).

Zonal mean subtropical easterly wind flow anomalies are starting to increase, and global relative AAM tendency has already become negative. As convection gets reestablished across the Indonesian region ~weeks 2-4, global relative AAM may decrease to at least 1 sigma below normal suggesting a re-loading of La-Nina (subseasonal perspective). However, seasonal cycle issues may also have an impact, and I do think we have seen the AAM bottom for this boreal cold season. Repeating from my last posting, we need to carefully monitor Southern Hemisphere zonal mean zonal wind anomalies this upcoming austral winter for ENSO insights.

The GWO is probable to do at least one circuit shifted toward octants 8-1-2 during the next 1-3 weeks. The corresponding GWO snr 250mb psi composite anomaly plots may best represent the global circulation the next few weeks. At some point GWO snr phase 3 (La-Nina base state) may return, meaning a positive phase of a Branstator (2002) circumglobal teleconnection favoring anomalous midlatitude ridges. The latter would not be good news to dampening many of the drought areas. Phases 4-5 of the MJO snr 250mb psi composite anomaly plots should loosely depict tropical circulation anomalies for the next few weeks. Obviously, phase 8 currently does not, which “tells you something” about calling the Western Hemisphere tropical convective dynamical signal (per velocity potential plots) a “MJO”.

More troughs are probable to impact the western and central USA during the next couple of weeks. While there will be a tendency for them to be progressive, I would not be surprised to see at least one more synoptic event similar (not the same weather) to the system currently pounding much of southwest Kansas with a blizzard as I write. At some point (perhaps late week 2/week-3) troughs may again dig off the west coast before shifting inland (trough-ridge-trough pattern for a period). Weather ramifications are understood, including internationally.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We appreciate all the support!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more):

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://ams.allenpress.com/archive/1520-0493/preprint/2008/pdf/10.1175_2008MWR2686.1.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry! I am planning on posting a discussion next weekend, 3-5 April.

Ed Berry

Update from the Midnight Rottweiler Rider

2009-03-21T15:09:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. This posting will be extremely short and hopefully coherent. A significant motivation to put “something out” is the extremely interesting on-going behaviors of the weather-climate dynamical system.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

Perhaps the “miracle” I was asking for per my last posting (14 March) is evolving. Multiple regions of enhanced tropical convective forcing are occurring across the globe. These include the quasi-stationary La-Nina signal ~0/100E, a “mixed GWO/MJO component” ~10S/155E, portions of northern Southern America and South Africa. For our purposes, the most important region is across the southwest Pacific Ocean (SWP; the 10S/155E signal), representing an enhancement of the SPCZ across very warm SSTs.

A well defined subtropical wave train (~25N) progressing through Asia is interacting with the SWP forcing. Divergent outflow from this strongly enhanced rainfall has locally strengthened the subtropical jet ~25N/180. Global relative AAM calculated tendency is solidly positive ~30 Hadleys, with contributions coming largely from the subtropical atmospheres of both hemispheres. There is evidence that zonal mean equatorward AAM transport is occurring ~30N, and synoptic behaviors such as northwest-southeast tilted eddies progressing off of East Asia support that. The bottom line is we do have a respectable perturbation on La-Nina, working to increase global westerly wind flow.

A probable regional-scale response will not only be the continued strengthening of the STJ impacting the southern USA, but possibly an eventual extension of the EAJ collapsing to more western states troughs ~weeks 2-3. These troughs may extend farther south helping to dampen areas experiencing drought. A superposition of phases 7-8-1-2 (models will struggle) of the snr 250mb psi MJO and GWO composite anomaly plots may best depict this situation.

Whether or not this subseasonal event is the start of a slow transition involving ENSO is unclear. Re-iterating, numerous GWO considerations tell us the La-Nina circulation anomalies will stick around. An important monitoring issue will be to see how intense zonal mean easterly wind flow anomalies become across the Southern Hemisphere subtropics during austral winter. Weather ramifications are understood, including internationally.

Appendix

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more) :

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. A pdf of an in press version can be downloaded from the following link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry!

I am planning on posting a complete discussion next weekend, 27-29 March. Will it still be the “same atmosphere different day (SADD)”?

Ed Berry

The Great Atmospheric Recession – La-Nina Hard Times

2009-03-14T15:03:00.000-07:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. There have been a few notable variations during the last few weeks. For instance, in contrast to about a year ago, equatorial Pacific Ocean SSTs have been cooling from the west coast of South America to ~120W, with anomalies ~minus 1-2C extending to depths of at least 100m. There has also been some warming from the far west central into the southwest Pacific, with anomalies ~plus 1-2C and totals approaching 30C. While weakened, the negative PDO signal is still present.

Overall, this is the time of year when the annual cycle of tropical ocean SSTs may be the most important in terms of ENSO. Whether or not the equatorial east Pacific Ocean cooling is "telling us something ", is unclear. Regardless, in my view the global atmosphere has generally been leading the Nino SSTs (including the official ONI) since at least December 2006. As discussed below, the La-Nina characteristics of the atmosphere remain well established. Variations understood (ex., 2007-08 and other events); at this point I would be surprised if I am not typing about La-Nina circulation issues a year from now (hopefully in a much better main streamed graphical medium than these discussions!).

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 19)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.io.gif

From the global ocean-land-atmosphere dynamical system perspective, our quasi-stationary La-Nina circulation base state is quite pronounced and probable to persist “until further notice (UFN)”. However, the subseasonal component interfacing weather and climate is about as complicated as it can get. While I do feel relatively comfortable about the details about the dynamical processes involved (within the WB (2009) GWO framework), and confident about the probable synoptic variations for at least the next several weeks, it is a challenge to write about. Obviously, transition seasons add difficulty. I am only going to “broad-brush”.

Enhanced tropical convective forcing is occurring across multiple regions of the globe. The most important tied to La-Nina is the area centered ~0/140E, extending from the far eastern Indian Ocean into the southwest Pacific. Generally diurnal convection continues across northern South America, and rainfall is anomalously intense over equatorial and South Africa. Rigorous daily monitoring of rapid baroclinic wave packets/zonally oriented Rossby wave energy dispersions (RWDs) interacting with tropics tells me the Western Hemisphere tropical signal was forced by the extratropics. In fact, through 13 March a greater than 1 sigma MJO projection was depicted in octant 8 of WH (2004) phase space (removing ENSO). In some sense, one can argue that there is a weak “GWO driven MJO”.

Coherent modes Hovmollers and other tools suggest the “140E tropical forcing” is drifting slowly west. Similar to many events earlier this year, a convectively coupled Rossby mode may be contributing to the westward movement. I do think there will be consolidation of this convection with the eastward propagating Western Hemisphere signal in the region of ~100-120E during the next couple of weeks. For reasons, I suspect much of the western and central equatorial Indian Ocean will again be “by passed”. The consolidation will help to maintain/reload La-Nina.

Through 12 March, while tilted toward the La-Nina attractor, there is only a weak projection on the WB (2009) measure of the GWO. Does this mean there is little information to be gained from it? The astute reader will answer, “absolutely not!” Once again there is a “La-Nina equilibrium of sorts” involving various time evolving components of the earth-atmosphere AAM budget (see plots) forcing a weak projection (for now).

For the last ~30 days a large GWO variation of roughly 3 sigma involving first eddy poleward AAM transports then strong surface torques worked to add westerly wind flow to the global atmosphere. Zonal mean contributions of anomalous westerly wind flow were ~10N and ~45N (responses in the Southern Hemisphere were much weaker). The former led to a sickly looking subtropical jet (STJ) into the southern USA (did bring needed precipitation to Texas) and latter a northward shift of the zonal mean storm track. However, intense anomalous zonal mean easterly wind flow also shifted poleward to ~30N, having weekly means ~12m/s. So, once again, anomalous midlatitude ridges are present across the Northern Hemisphere extratropics, similar to the positive phase of a Branstator (2002) circumglobal teleconnection. Phase 2 of the GWO 250mb snr psi composite anomaly plots loosely depict the global circulation, especially the extratropics.

Overall, like that seen during the 2007-08, and typed so many times this cold season, there is nice interhemispheric (mainly northern; austral warm season) meridional symmetry of zonal mean zonal wind anomalies. Furthermore, consistent with the tropical forcing, animations of upper tropospheric daily mean vector wind anomalies do suggest the Indian Ocean (west Pacific Ocean) anticyclones (cyclones) are in the process of getting reestablished. Phase 4 of the MJO snr 250mb psi composite anomaly plots best depicts tropical circulation anomalies. In general, with variations, phases 4-5 of these MJO composites may best represent the tropics UFN.

The whole above spiel simply tells us the global circulation is “classic La-Nina”, and is probable to continue, again, UFN. I do expect the GWO to resume its orbit in phase space, roughly octants 1 to 4 then back with periods perhaps ~20-30 days. Similar to a year ago, these orbits may spiral upward. However, an important difference between this boreal winter and last year is the lack of relatively robust slower subseasonal variations including MJOs compared to a year ago.

Utilizing the GWO and MJO snr composites for ~week 1-4 predictions may be quite challenging in these hard times. This is where “Rottweiler experience and understanding of this stuff” is needed. Loosely, focusing on the lower 48 states, I think we are going to continue seeing synoptic alternations between east Pacific Ocean troughs/western and central states ridges/east coast troughs with western troughs and southeast states ridges. The latter may become preferred heading through spring (was a year ago with the subseasonal activity), and the storm track is probable to remain shifted north.

Weather ramifications are understood, including the likelihood and expansion of worsening drought conditions (rangeland wildfires, dust storms, etc.) across the central and southern High Plains. If any “miracles” can happen (ex., resumption of MJOs) and stronger STJs can be directed into the USA Desert Southwest, that will help to mitigate at least some of the dryness. The latter could also help other parts of the country experiencing drought. The Pacific Northwest is likely to remain excessively wet for at least the next 2-4 weeks.

I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide. An elevated risk of tropical cyclones is probable perhaps both sides of the equator in the region of Indonesia and northern Australia weeks 1-2. In fact, that concern may focus from the northeast coast of Australia into the region of the South Pacific islands, given warm SSTs, weakly anomalous surface westerly winds and other reasons.

Appendix

All presentations from the 24 February 2009 GWO workshop are available via anonymous ftp. If you have not received information on how to retrieve these, let me know. There was excellent attendance at this day-long event, and feedback was strongly positive. We appreciate all the support!

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

http://www.cdc.noaa.gov/forecasts/clim/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. A pdf of an in press version can be downloaded from the following link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, extremely unscientific, and makes the Rottweiler VERY angry!

I will not be able to post another discussion until the weekend of 27-29 March due to covering operational overnight shifts. It may just be the “same atmosphere different day (SADD)” anyway!

Ed Berry

AAM Rally in a Bear Atmosphere

2009-03-06T14:12:00.001-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. Little overall change has occurred during the past week. The anomalously cool SSTs recently observed across much of the North Tropical Atlantic Ocean and portions of the Caribbean may have had a significant contribution from extratropical processes. For instance, cold surges accompanying digging troughs into Europe have plunged well south into the tropics during much of the winter, as have similar surges off the USA east coast. The cold front that accompanied the eastern states snowstorm earlier this week is nearing the north coast of South America as I type.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

While displaced toward low AAM in phase space, a large, roughly 3 sigma variation of the WB (2009) measure of the global wind oscillation (GWO) has been occurring since roughly 12 February. This behavior has been the dominant component of the subseasonal weather-climate dynamical system within a well established La-Nina base state. The orbit has involved approximately octants 1-4, having a magnitude similar to those seen during boreal fall 2008. The dynamical processes explained by the GWO have been working to try to bring global westerly wind flow back to normal, somewhat analogous to Le Chatelier’s Principle for chemical equilibrium. However, I also think we are seeing an atmospheric variation analogous to a bear stock market rally, and, unfortunately, Le Chatelier’s principle cannot be applied to the latter.

More specifically, the current GWO orbit in phase space is relatively “clean’, following the chain of events outlined in WB (2009). This dynamical measure of the global circulation also provides some quantitative evidence that the extratropics have been recently forcing the tropics. Broadly, there was first strong poleward AAM transport during the first half of February centered ~35N, followed by a strong positive global frictional torque, then global mountain torque. Please see AAM plots for details. Presumably involving the eddies and mass circulations (on our list to quantify along with real-time diagnostics), downward transport of anomalous subtropical easterlies ramped up the frictional torque. Anomalous high surface pressures then increased the global mountain torque. Through 4 March, global relative AAM tendency is again becoming negative, forcing the GWO toward Octant 1 while orbiting around the La-Nina attractor.

Primarily zonally oriented Rossby wave energy dispersions (RWDs), observed during the past several weeks, linked to these complicated dynamical processes have subsequently impacted the deep tropics. For example, the upper tropospheric anomalous twin subtropical cyclones connected with La-Nina were forced west of the Dateline. Intense zonal mean easterly wind flow anomalies that have been dominating the subtropical atmospheres have also weakened a bit, while shifting poleward. In fact, there is even anomalous zonal mean westerly wind flow across the northern subtropics (~5m/s at 200mb), regionally in the Western Hemisphere.

All of these processes have been trying to “jump start” the atmosphere. Regional scale responses have included progression of the PNA central Pacific Ocean ridge-USA west coast trough pattern, and an amplifying central North Atlantic Ocean ridge (not the NAO; this is a dipole of anomalies). As expected given the GWO orbit, these synoptic evolutions can be seen fairly well from looking at phases 1-4 of the GWO 250mb snr PSI composite anomaly plots.

Consistent with our quasi-stationary La-Nina base state, tropical convective forcing remains loosely focused on Indonesia, centered ~0/120E. Per above, a “poor excuse” of a subtropical jet extends from the Northern Hemisphere twin subtropical cyclone near the Dateline into the USA Desert Southwest (with lots of mid/upper tropospheric cloud cover). At least diurnal convection continues across tropical South America and Africa. Retaining the interannual signal, the WH (2004) measure of the MJO has ~1.5-2 sigma projection in octants 4-5 of phase space. Subtracting out ENSO, the signal is much weaker. In this case, the latter is more realistic (need to understand how to interpret any index; the Rottweiler is always watching!), the MJO signal is negligible. Phases 4-5 of the MJO snr 250mb PSI composite anomaly plots best represent tropical circulation anomalies, as they generally have since boreal fall 2008.

Where does the atmosphere go from here? Unlike the current financial markets, relative AAM may have found a “bottom” for the boreal 2008-09 cold season. This behavior would be consistent with that seen a year ago. As I have already typed in past postings, La-Nina circulation anomalies are likely to linger well into spring (at least), with synoptic variations tied to GWO. Synoptic responses shown by the GWO snr 250mb PSI (and other variables) composite anomaly plots for ~phases 8-1 to 4-5 shifted toward low AAM are probable “until further notice”. These will work with the seasonal cycle. This suggests a preference of more progressive western and central states troughs. However, like the stock market volatility (and different from a year ago), there will be deviations including eastern USA troughs and transient ridges from Hell.

Numerical model performance has suffered significantly during the last several weeks literally due to the GWO. I think their forecasts for the next ~5 days are useable (predictability always decreases during transition seasons). During weeks 2-3, the added subtropical westerly wind flow (per above) may help to extend the East Asian jet (shifted north) into the western USA. That may contribute to more energetic progressive troughs including their expected possible high impact weather. This does include warm sector severe local storms (remembering tropical moisture transports issues through the Gulf of Mexico) and cold sector (thunder) snowstorms with individual baroclinic cyclones. However, drought conditions are probable to continue intensifying across the central and southern High Plains.

I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide. Notable events continue. Locations centered on Indonesia and working into the Philippines are likely to get hammered with intense-severe tropical thunderstorm activity for at least the next 2-4 weeks. An elevated risk of tropical cyclone activity is probable around the north coast of Australia the next 1-2 weeks.

Appendix

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is (still) awaiting publication in MWR. A pdf of an in press version can be downloaded from the following link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, and extremely unscientific!

I will attempt to post a discussion the weekend of 14-15 March 2009.

Ed Berry

La-Nina Impacts HIGHLY Probable to Continue at Least well into Boreal Spring 2009

2009-02-27T13:44:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Please see links below for global SST details. Negative SST anomalies across all Nino regions have warmed ~1C during the last few weeks. There has also been some warming at depth along the equatorial ocean thermocline from ~140E to the west coast of South America (per TAO buoy data). However, similar to a year ago, a contribution to the warming may be the annual cycle. Recall during late boreal fall 2008 the Nino SSTs responded to the global circulation that was already exhibiting El-Viejo characteristics. Utilizing Nino 3.4 SSTs including the ONI as a measure of the ENSO situation was unrepresentative at that time, and that may be the case well into Northern Hemisphere spring.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

The global ocean-land-atmosphere dynamical system is well entrenched in a quasi-stationary La-Nina base state. In fact, and possibly linked to recent tropospheric impacts from the January 2009 major sudden stratospheric warming (SSW), global relative AAM is at the lowest value so far. Updated through 25 February, global relative AAM was ~minus 2.5 standard deviations below the R1 data climatology, similar to a year ago during the strong La-Nina. Put another way, just like the stock market has found a new “bottom”, so has AAM. Conditions in the stratosphere have returned to about normal.

The WB (2009) measure of the GWO during the last 40 days has ~2 sigma displacement toward octants 2-3 of phase space, essentially the La-Nina attractor. Not wanting to get too involved with the details of the current earth-atmosphere AAM budget (see plots), I think there may be another equilibrium "of sorts" of physical processes going on. For instance, the global frictional torque has recently spiked to ~plus 20 Hadleys, with most of that coming from enhanced trades. A portion of the latter may be coming from zonal mean negative AAM anomalies being brought down to the surface via mass circulations (enhancement of the Hadley cell; see earth AAM). In any case, this is an example of the atmosphere trying to get out of La-Nina, analogous to recent stimulus packages attempting to halt economic recession. There has also been an abrupt poleward shift of zonal mean AAM transport from ~35N to 50N, with a weak subtropical source. The latter is not good news for Northern Hemispheric locations experiencing drought.

Observationally, there have been several rapid variations involving zonally oriented Rossby wave energy dispersions (RWDs)/dispersive baroclinic wave packets during the past several weeks. In addition to causing difficulties with global numerical model predictions, these RWDs have also disrupted some of the tropical convective forcing. However, per full disk satellite imagery, enhanced rainfall is consolidating near 0/120-140E, while both tropical South America and Africa remain active. Retaining the interannual signal, through 26 February there is ~2 sigma MJO projection in octant 4 of WH (2004) phase space. However, in reality, there is no physically significant MJO variation of tropical convective forcing currently going on (past rogue MJO understood!).

Interhemispheric meridional symmetry of zonal mean zonal wind anomalies is well pronounced, including easterlies across the subtropical atmospheres. For the first time in at least a few weeks, the upper tropospheric zonal asymmetric portion of tropical circulation anomalies has returned. There are well defined twin cyclones near the Dateline (~30-40m/s anomalies at 150mb) with weaker anticyclones across the Indian Ocean. Anomalous midlatitude ridges continue to dominate the extratropics.

A loose superposition of phases 2-4 of both the GWO and MJO snr 250mb psi composite anomaly plots best depict the current global circulation. This type of circulation is probable to persist well into March, and possibly most of this upcoming spring. Because of on-going feedback processes not discussed, phase 5 of the MJO snr OLR composite anomaly plots may best represent the current tropical forcing, and, on average, may continue “until further notice”. The latter has generally been the case for the past 90 days.

Regardless of the details, little change in the overall synoptic pattern across the PNA sector is likely for at least the next several weeks. The La-Nina (and ENSO variations in general) characteristics of a global circulation “suddenly do not just go away (for reasons; insert angry Rottweiler!)”. There will be variations with the seasonal cycle, including shortening wavelengths that could lead to deep troughs across the central USA states (for example). More generally, on average, the outcome of temperature and precipitation anomalies for the lower 48 states during March-June 2009 may have some similarities to that same period during 2008. However, unlike 2008, subseasonal activity this boreal winter has been much weaker. While that could change, compared to a year ago, I am concerned that an outcome for boreal spring 2009 that is more consistent with the La-Nina composite signal may occur. This includes intensifying drought with anomalous warmth across the central and southern High Plains into Texas, possibly spreading northeast (see the U.S. Drought Monitor for other areas).

I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide. There have been some recent notable events, including extremely active weather from portions of the Mediterranean Sea into the Middle East. The latter may continue for at least another couple of weeks. Locations centered on Indonesia are likely to get hammered with intense-severe tropical thunderstorm activity for at least the next couple of weeks

Appendix

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM (3^rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html .

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), is awaiting publication in MWR. A pdf of an in press version can be downloaded from the following link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook, and extremely unscientific!

I will attempt to post a discussion the weekend of 6-8 March 2009.

Ed Berry

Circulation Hell Discussion Delayed

2009-02-20T17:07:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Because of preparations for the 24 February GWO workshop in Boulder, I am unable to post a “decent” discussion this weekend. I will attempt to do one ~27 February. A “quickie” is given after the SST links.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

The global circulation is well entrenched in a quasi-stationary La-Nina state. In the WB (2009) GWO sense, the current El-Viejo characteristics are similar to this time last year. Global relative AAM is ~2 standard deviations below the R1 data climatology, and zonal mean easterly wind flow anomalies dominate the subtropical atmospheres. Processes involving fast Rossby wave energy dispersions (RWDs), AAM transports and the surface torques are contributing to what may be ~20-30 day variations of the GWO tilted toward the La-Nina attractor in phase space. In fact, the latter have recently caused some disruption to the tropical convective forcing.

Impacts from the recent major SSW onto the troposphere continue to linger. Please remember that the dynamics responsible for the upward propagation of tropospheric wave energy leading to the SSW were linked to poorly understood non-linear feedbacks (multiplicative noise?). These issues go back to the “rogue MJO” event previously discussed. An important point is to be careful over interpreting “causes and effects”, especially when data sets and sample sizes are limited (food for the Rottweiler!). In any case, blocking structures continue across the Northern Hemisphere polar latitudes, and the zonal mean storm track has been shifting south (to ~35N) during the last couple of weeks.

With variations, a loose superposition of phases 3-5 of the snr 250mb psi composite anomaly plots are probable to characterize the global circulation for at least the next several weeks. Tropical convective forcing is also probable to reorganize ~120E as well. Regionally, a continuation of progressive troughs impacting the western USA then shifting into the Plains is likely. Weather ramifications should be understood. Should the storm track continue to shift south against climatology, even portions of the dry southern High Plains may get needed precipitation going into boreal spring. Overall, I think it is fair to offer the weather across the USA lower 48 states spring 2009 will have some similarities to 2008. The latter includes the possibility of an active Plains severe local storm season.

I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide. There have been some recent notable events.

Appendix

Links to CPC and PSD ENSO discussions, and a new experimental forecast technique involving a coupled LIM approach (3rd link below):

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html .

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

I will attempt to post “something” ~27 February 2009.

Ed Berry

Update from the Depths of Circulation Hell

2009-02-12T16:50:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading the following.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

This discussion simply extends what was posted on 7 February. There is little overall change to the global SSTs. Roughly minus 1C anomalies continue across all Nino regions, and the warmest SSTs persist around New Guinea with totals ~30C. Please see links below.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

The global ocean-land-atmosphere dynamical system can be summed up as a solidly quasi stationary La-Nina state. While individual components may not be overly robust, working in cooperation the character of the global circulation is not much different than about a year ago. An important exception is that impacts from the SSW continue on the Northern Hemisphere troposphere (discussed in past postings). From a research and speculative point of view, a “stable equilibrium of sorts” involving the dynamical processes explained by the WB (2009) measure of the GWO may be going on.

Tropical convective forcing has drifted slightly farther west to ~0/120E extending from the central Indian Ocean to just east of Australia. Any MJO signal is very weak. The ~1.5 sigma projection in octant 5 of WH (2004) phase space retaining ENSO is an artifact of the computation methodology. In contrast to late December 2008 into January, an eastward propagating signal is unlikely for at least the next 1-2 weeks.

Global relative AAM has crept up to ~1 standard deviation below the R1 data climatology (through 10 February). Contributions have included the surface torques and, indirectly, the eddy transports. The latter does not have a global signal, but can strongly contribute to the zonal mean. In fact, flanked by zonal mean sinks, there has been a well-defined source ~40N for about the last week. A response has been for some intensification of the zonal mean Northern Hemisphere polar jet, with a slight southward shift. However, there is little change to the pattern of anomalous midlatitude ridges characteristic of the positive phase of a Branstator (2002) circumglobal teleconnection (with strong interhemispheric symmetry) as discussed in the 7 February posting.

The WB (2009) GWO is currently doing a slow orbit shifted toward the La-Nina attractor in phase space. I do think global AAM tendency will become negative allowing the circuit to continue. A loose superposition of GWO phase 3 and MJO phases 4-5 of the snr 250mb psi and OLRA composite anomaly plots still best characterizes the global circulation and tropical rainfall. This includes the central North Pacific Ocean ridge with downstream progressive troughs impacting the west coast into the lower 48 states. I think this situation will continue for at least the next 2 weeks, and perhaps well into boreal spring. With synoptic variations (ex., low amplitude ridge across the central states at times), weather ramifications should be well understood. I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide (there has been an increase).

Appendix

The formal announcement for the 24 February 2009 one-day (~830am-530pm MST) workshop on the WB (2009) GWO has been released through various mailing lists, and is available on the ESRL/PSD GSDM web link. If you have not already done so, please send an email confirmation of your attendance asap.

Links to CPC and PSD ENSO discussions:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

Discussions continue to be very difficult to publish given shift work and preparations for the GWO workshop. I will attempt to post “something” ~20-21 February 2009.

Ed Berry

Deep in the “Strange Brew” of La-Nina and SSW; Several Rounds of USA High Impact Weather are Likely Weeks 1-3

2009-02-07T14:38:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Map room issues continue and are being worked on.

Please see links below for SSTs. Strengthening trades during the last week has renewed cooling of SSTs across all Nino regions. TAO buoy data show 5-day averaged anomalies ~minus 1-1.5C along the equatorial Pacific Ocean cold tongue, with the 29C total SST isotherm back to near 160E. Our downwelling oceanic Kelvin wave (~150m depth) may be loosing some coherence as it propagates into the east Pacific. SSTs have also cooled across the west central and Southwest Pacific Ocean with totals generally less than 30C. The latter is likely a response to the recent strong tropical convective flare-up ~10S/160E about a week ago.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecasts/sstlim/Seas.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

The global weather-climate situation is extremely complicated. While I do feel comfortable with any diagnosis I can offer, this medium of communication is not a good facilitator. From my viewpoint of the global ocean-land-atmosphere dynamical system, La-Nina is well entrenched. Tropical convective forcing has consolidated nicely ~0/130-140E extending from the East Indian Ocean into the SPCZ. WH (2004) MJO phase space plots show greater than 2 sigma projections in octant 5 without ENSO and approaching a nearly 3 standard deviation anomaly with it. However, this empirical technique reflects what I think is a resurgence of our quasi-stationary La-Nina base state. I do not think we have an eastward propagating signal like that observed during early-mid January. Phase 5 of the WH (2004) measure of the MJO OLRA snr composite plot nicely depicts the current situation of tropical rainfall.

The wind and convective signals are loosely getting back into sync, as are the tropics and extratropics. A “messy” Eastern Hemisphere subtropical transition to anomalous upper tropospheric East Indian Ocean (central Pacific) twin anticyclones (cyclones) continues. The latter is the zonally asymmetric component of tropical wind anomalies characteristic of a cold event.

However, similar to a year ago and not cleanly observed during this “encore”, there is now respectable interhemispheric meridional symmetry of zonally symmetric zonal mean zonal wind anomalies. These include ~5m/s 200mb zonal mean easterly wind flow anomalies throughout the Northern Hemisphere subtropical atmosphere, and easterly anomalies in excess of 10m/s ~75N (more said below). Reflective of a poleward shifted zonal mean polar jet; 200mb westerly wind flow anomalies of roughly 5m/s exist at 45N.

Also similar to the 2007-08 strong El-Viejo, the Northern Hemisphere midlatitude circulation is characterized by anomalous ridges suggesting a positive phase of a Branstator (2002) circumglobal teleconnection. Phase 3 of the GWO 250mb psi snr composite anomaly plot depicts this situation. Along with phase 4 for the MJO depicting tropical anomalies, a superposition of these composites is broadly representative of the global circulation. This response may continue for the next several weeks.

Updated through 3 February, global relative AAM is ~1.5-2 sigma below the R1 data climatology, an upward trend from its low of ~minus 2.5 sigma a couple of weeks ago (bear atmosphere rally?!). Including contributions from the surface torques, relative AAM tendency has increased to ~plus 15 Hadleys the last week or so. However, the WB (2009) measure of the GWO remains locked in octants 3-4 of phase space, strongly shifted toward the La-Nina attractor comparable to that observed during the 2007-08 boreal winter/spring. I do think a slow orbit is probable during the next few weeks, tilted toward La-Nina.

The record breaking (data going back to 1978) major sudden stratospheric warming (SSW) continues. See links in the Appendix for details. The zonal wave number 2 pattern of Northern Hemisphere higher latitude anomalous continental cyclones (~100E ad 100W) and ocean ridges bridging the pole has propagated down to at least 200mb. Surface weather across large portions of the Northern Hemisphere is already being impacted. A synoptic response has been for the European blocking (which played a role in the recent UK snowstorm) to retrograde into central Atlantic Ocean. The latter does not (yet) project strongly on the negative phase of the NAO, and serves as another example why it is important to understand the dynamics of teleconnections (the Rottweiler is always watching!).

In any case, arguably GWO processes starting December 2008 contributed to the SSW, and now the SSW is feeding back to the GWO. For instance, the polar latitude strongly anomalous upper tropospheric zonal mean easterly wind flow is helping to keep global AAM low, in a sense constructively interfering with La-Nina. Furthermore, AAM eddy transports from both the subtropics and high latitudes may be contributing to the anomalous westerly wind flow ~45N. Regardless of the details, working with what may be a maturing quasi-stationary La-Nina base state, tropospheric impacts from the SSW will continue for the next several weeks. Stratospheric time scales are very slow.

Regionally, the central Pacific Ocean ridge-expanding western USA states trough is probable to continue through the next 2-3 weeks. Blocking retrogression through Canada, perhaps bridging the Atlantic and Pacific Ocean ridges, is likely to keep an active storm track over much of the central and southern lower 48 states (in contrast to the poleward displaced zonal mean polar jet). There may be a period of anomalous cold and wet for much of the country, including an elevated risk of high impact weather (all types; should be understood), particularly ~week-2.

Somewhat typical of a La-Nina, much of the Arctic air (surface temperatures well under minus 50F across Siberia) is displaced toward Asia. However, some of this air will “bleed” back into the USA the next few weeks, ending the current respite from the cold winter for locations such as the Upper Mississippi Valley. Speculating farther, while March-June 2009 may have weather similarities to that period during 2008, the seasonal northward migration of the polar jet may be delayed. Including impacts from the severe tropical thunderstorm activity centered on Indonesia and northern Australia, I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide.

Appendix

The formal announcement including an additional expanded outline for the 24 February 2009 one-day (~830am-530pm MST) workshop on the WB (2009) GWO has been released through various mailing lists, and is available on the ESRL/PSD GSDM web link. Let me know if you have not seen it. Please remember the intended audience of this workshop is forecasters who make daily subseasonal predictions. It will not be a “head banger’s academic ball”.

Links to CPC and PSD ENSO discussions:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following are links to information about the stratosphere and other nice monitoring tools:

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html .

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

Discussions will be very difficult to publish the next few weeks given shift work and preparations for the GWO workshop. I will attempt to post “something” ~13-15 February.

Ed Berry

Update: La-Nina + Major SSW = Where the Atmosphere has Never Gone Before?

2009-01-30T07:48:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Some map room plots are still missing due to on-going upgrades. These issues are being worked on.

This will again be short! Please see links below for SSTs. Local and relatively shallow warming of equatorial Pacific Ocean SSTs has occurred west of South America, similar to a year ago. Anomalies are ~plus 1-2C. Tropical-extratropical interactions linked to the recent strong MJO and seasonal issues may be contributing. Our respectable downwelling oceanic Kelvin wave ~150m depth has propagated to about 150W. Any future impacts from the latter are unclear. Stay tuned. The warmest SSTs globally persist across the southwest Pacific, with totals ~30C in the region of New Guinea.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

La-Nina is reloading. Tropical convective forcing has returned to the Eastern Hemisphere with some consolidation ~0/120E while a somewhat separate region persists across the warm southwest Pacific Ocean. The MJO signal has weakened. There is little projection in WH (2004) phase space removing interannual component, but ~1.5 sigma in octant 3 (through 28 January) retaining it, reflecting the resurgence of La-Nina. Monitoring will tell if another eastward propagating signal of tropical forcing evolves. Other options include two areas such as a quasi-stationary Indonesian region concurrently with episodic southwest and west central Pacific strong to severe tropical convection.

Global relative AAM is approaching negative anomaly magnitudes comparable to the 2007-08 strong La-Nina. Updated through 26 January, AAM was ~2.5 sigma below the R1 data climatology forcing the WB (2009) measure of the GWO deeply (~2 sigma) into octants 2-3 of phase space. Zonal mean easterly wind flow anomalies have become quite strong throughout the equatorial and subtropical atmospheres, ~5-10m/s at 200mb, and up to 15m /s across Northern Hemisphere polar latitudes. The latter is a response to a sudden stratospheric warming (SSW; more said below). A loose superposition of phase 3 for both the 250mb snr psi composite anomaly plots of the MJO and GWO generally represent the global circulation, and that should continue for at least the next 2-3 weeks. This means our familiar pattern of anomalous midlatitude ridges including the central Pacific Ocean favoring a trough in the region of western North America.

Forced by (unpredictable) dynamical processes responsible for the strong west coast ridge a couple of weeks ago (see 23 January posting), a major SSW is in progress. In fact, data records going back to 1978 (see new stratosphere monitoring link in the Appendix) suggest this SSW is the strongest given this time of year. A well pronounced zonal wave number two circulation structure in the stratosphere is present, with lobes of the polar vortex across the Arctic latitudes of North America and Asia. Interacting with the La-Nina base state, the troposphere is already being impacted, and that will continue for at least the next several weeks. Large anomalies of zonal mean easterly wind flow is propagating downward into the upper troposphere of the Northern Hemisphere high latitudes as I type.

Synoptically, a possible regional-scale response is for tropospheric blocking initially across Scandinavia to retrograde through the North Atlantic and Canada then into the North Pacific Ocean during the next few weeks. The NCEP GEFS and other ensembles are starting to capture this scenario. That suggests the storm track should shift south across the lower 48 states of the USA later week-2 and perhaps continue most of February. Additional feedbacks (not discussed) from the South Pacific Ocean tropical forcing may also contribute to bringing the storm track farther south. Areas that have been anomalously dry this winter may get much needed precipitation. In fact, there may be some weather similarities to February 2008 across the USA next month. I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide.

Appendix

The formal announcement for the 24 February 2009 one-day (~9am-5pm MST) workshop on the WB (2009) GWO has been released through various mailing lists. An extended outline was sent today, 30 January, which should also be avialable from the ESRL/PSD GSDM web link. Let me know if you have not seen it. Please remember the intended audience of this workshop is forecasters who make daily subseasonal predictions. It will not be a “head banger’s academic ball”.

Links to CPC and PSD ENSO discussions:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

The following are links to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

http://code916.gsfc.nasa.gov/Data_services/met/ann_data.html (new stratosphere link!)

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), has been accepted for publication MWR. A pdf of the in press version can be downloaded from thefollowing link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook! I plan on posting at least an abbreviated discussion on ~7 February 2009.

Ed Berry

Reloading La-Nina, but with a SSW twist???

2009-01-23T11:25:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

Many map room plots are missing due to on-going upgrades. These issues are being worked on.

This will be short! Some warming of SSTs has occurred across the far west central equatorial Pacific Ocean (totals ~30C) as well as the west of South America. The latter may be a similar occurrence to a year ago. Overall, global SSTs remain “steady state” including ~minus 1C anomalies (warmed slightly) across all Nino regions.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.pmel.noaa.gov/tao/jsdisplay/

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

The global ocean-land-atmosphere dynamical system is recovering from the recent strong perturbation on La-Nina. Importantly, linked to MJO convection across the South Pacific Ocean at the time, there was large amplitude meridionally directed Rossby wave energy dispersion (RWD) across the North Pacific Ocean (with Southern Hemisphere symmetry). The RWD forced the westward shifted PNA ridge that was responsible for the severe cold outbreak centered on the Upper Mississippi Valley last week. Several diagnostics (including EP fluxes) indicate that tropospheric wave energy from this RWD has propagated into the stratosphere and a sudden stratospheric warming (SSW) may have been initiated. More said below.

The MJO signal is centered on Africa, and interactions with extratropical wave energy propagations are intensifying deep convection across the equatorial Indian Ocean. Zonal mean easterly wind flow anomalies (~5m/s at 200mb) have returned to the tropical and subtropical atmospheres. Updated through 21 January, global relative AAM is already ~2sigma below the R1 data climatology, the lowest since early October 2008. I do expect a further decline (like our recent financial markets!).

Summing up, a coupled GWO/MJO evolution from octants 7-8 the last week or so into at least 3-4 in phase space is likely the few weeks, constructively interfering with La-Nina. The global circulation shown by ~phase 3 of the 250mb snr psi composite anomaly plots for the GWO and MJO appears probable by week-2. This means our familiar pattern of anomalous midlatitude ridges, including the central Pacific Ocean ridge and a downstream trough in the region of western North America.

Regionally, the on-going discontinuous PNA retrogression is similar to that observed early December 2008. This is being forced by the current weakened La-Nina base state including residual Indonesian tropical forcing. As La-Nina reloads the next few weeks, troughing is likely to return to the Gulf of Alaska then extend into western North America. In contrast to the high confidence outlooks for the USA issued November 2008 for December, it is unclear how far southeast these next series of troughs may extend into the western USA. Should the storm track remain anomalously shifted poleward, dryness may intensify over portions of (for example) the central and southern Plains. Typical of a La-Nina base state, the Northern Hemisphere polar vortex retracted during late December, and that has been the case until very recently.

However, unusual for La-Nina, and essentially not observed during the 2007-08 cold event, a serious monitoring issue the next 30-40 days will be if a possible SSW disrupts the polar vortex. Depending on timing of behaviors, including the possibility of another MJO coming out from the Indian Ocean into the west Pacific ~weeks 3-5, there may be significant weather impacts on the USA which are currently unclear. Stay tuned. I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide.

Appendix

The formal announcement for the 24 February 2009 one-day (~9am-5pm MST) workshop on the WB (2009) GWO has been released through various mailing lists, and is available on the ESRL/PSD GSDM web link (cited above). Let me know if you have not seen it. Please remember the intended audience of this workshop is forecasters who make daily subseasonal predictions. It will not be a “head banger’s academic ball”.

Links to CPC and PSD ENSO discussions:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/

The following is a link to information about the stratosphere and other nice monitoring tools:

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/index.html

The following is a link to NCEP model verifications (surf around for lots more)

http://www.cpc.ncep.noaa.gov/schemm/z500ac_wk2_na.html

The following is a link discussing recent global weather and related events:

http://www.wmo.ch/pages/mediacentre/news/index_en.html

These are probabilistic statements. We hope that an opportunity will arise for us (soon) to allow our dedicated web page effort to mature, expediting objectively and accountability. This web page effort will hopefully include an objective predictive scheme for the GWO with hindcasts.

The WB (2007) paper on the GSDM has been published in the February issue of MWR. The first of a two-part paper, where WB formally introduce the GWO (WB (2009)), has been accepted for publication MWR. A pdf of the in press version can be downloaded from thefollowing link:

http://www.cdc.noaa.gov/map/clim/wb08_revised_final.pdf

In addition to the subseasonal snr composite anomaly plots, we would like near real-time discussions with “weather maps” to become a routine part of the ESRL/PSD GSDM web site sometime soon. Part-2 of our GWO paper will discuss the latter. We want to emphasize notions such as global-zonal mean-regional scale linkages as well as forcing-response-feedback (with subsequent interactions) relationships. An important purpose is to provide a dynamical weather-climate linkage framework to evaluate the numerical models in a sophisticated manner as part of a subseasonal (and any time scale) forecast process, in addition to a climate service for all users. Relying on the numerical models alone is a cookbook! I plan on posting at least an abbreviated discussion on ~30 January 2009.

Ed Berry

Update: Rogue “MJO Wave”, then “La-Nina Reloaded”

2009-01-17T13:41:00.000-08:00

“The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

Please keep in mind the ESRL/PSD GSDM web link, below, while reading this discussion.

http://www.cdc.noaa.gov/map/clim/gsdm.composites.shtml

The 91-day signal to noise ratio (snr) anomaly composites are being updated daily. There are still map room issues that are being worked on. WB (2009), part-1 of a 2 part paper where the GWO is formally introduced, is in press for MWR publication. There is a link in the Appendix to download the manuscript.

The formal announcement for the 24 February 2009 one-day (~9am-5pm MST) workshop on the WB (2009) GWO has been released through various mailing lists. It can also be obtained from the GSDM web page per above link. Please remember the intended audience of this workshop is forecasters who make daily subseasonal predictions. It will not be a “head banger’s academic ball”. The workshop is open all interested; private, government, etc..

This posting is significantly abbreviated due to upcoming travel. In fact, I would like that to be a trend, particularly if a real-time web page with "maps and figures", as a component of the GSDM site, can evolve.

Global SSTs remain relatively steady state, as would be expected since their anomalies are generally slowly evolving. Slight warming has been occurring across the convectively suppressed South Indian Ocean, while a downwelling Kelvin wave continues its slow propagation into the Western Hemisphere equatorial Pacific Ocean. The latter, forced by weakened trades and actual surface westerlies, is ~150m deep having anomalies roughly plus 2-3C per latest 5-day averaged TAO buoy data. Subsequent impacts, if any, are unclear.

http://www.wmo.int/pages/prog/wcp/wcasp/enso_update_latest.html

http://iri.columbia.edu/climate/ENSO/currentinfo/technical.html

http://www.cdc.noaa.gov/map/images/sst/sst.long.time.gif

http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html (link 18)

A much stronger than expected MJO signal is propagating through the Western Hemisphere, located in octant 7 of WH (2004) phase space with and without the interannual retained. For this case, the ~2.5 sigma projection without ENSO is realistic (there are reasons). Satellite imagery and other tools suggest the MJO dynamical signal is centered on the Americas, with an eastward propagation phase speed of ~20-25m/s. These do progress significantly faster across the Western Hemisphere. I expect the MJO to easily re-emerge into the Indian Ocean during week-2.

While arguably unpredictable with appreciable lead-time, I am not surprised by this “rogue MJO”, and I do think scientifically defensible attribution can be offered (perhaps as one of the cases for the GWO workshop). In fact, concerns of this possibility including weather impacts were expressed in discussions last (boreal) fall. The gist is red noise dynamical processes captured by the WB (2009) measure of the GWO, working with the annual cycle, likely forced the coherent eastward propagating convective signal (south of the equator) projecting on a MJO.

The circulation response has included subtropical transition of upper tropospheric anomalous anticyclones (cyclones) to cyclones (anticyclones) across the Indian Ocean (west Pacific Ocean), and extension the East Asian jet (EAJ) forcing a large positive phase (shifted west) of the Pacific North American teleconnection (PNA). Phases 6-7 of the MJO 250mb snr psi composite anomaly plots depict the global tropical and even extratropical circulation. The recent severe USA cold Arctic outbreak that focused on the northern and central Plains-Northeast is directly linked to all the above.

The GWO (R1 data AAM plots updated through 15 January) has shown little variation and projection since early this month, shifted slightly toward La-Nina in phase space, suggestive of the on-going interannual component. However, just as the MJO destructively perturbed La-Nina, rapid constructive interference is very likely the next 1-3 weeks as it's signal returns to the Eastern Hemisphere. The surface torques are collectively becoming negative contributing to an already ~minus 20-30 Hadley AAM tendency. A sink-source zonal mean AAM poleward transport signal has also appeared across the subtropical and midlatitude atmospheres of the Northern Hemisphere. Hence the GWO has spiked into octant 1 of phase space. I do think a relatively synchronized GWO/MJO 7-8-1 transition is starting, and all that should lead to a global circulation depicted by phases 2-3 of the 250mb snr psi composite anomaly plots. As is typical during these types of regime transitions (on our list to quantify), all global numerical weather prediction models have been struggling badly the last several days.

The long awaited PNA discontinuous retrogression will start week-1, responding to lingering Indonesian tropical forcing. The “western trough/southeast ridge pattern” should mature by ~ week-3 as Eastern Hemisphere tropical forcing intensifies, having USA weather ramifications similar to December 2008. Monitoring will tell if this situation “locks in”. Remember that while also stronger than expected, the 2008-09 La-Nina encore is still “pale” by comparison to a year ago (as is typical). In any case, keeping in mind climatology, I do have some concern of one or two significant/severe baroclinic winter storm developments focusing on the Plains roughly weeks 2-3. There should also be concerns that at least portions of the Plains during the next several months may have weather ramifications similar to late winter-spring 2008.

Intense to severe tropical thunderstorm activity is probable to shift from South America and South Africa week-1 into the equatorial/South Indian Ocean week-2 (a large change). The focus should be from the Indian Ocean into Australia and Indonesia by week-3. The lingering convection currently centered on Indonesia is a response to the La-Nina global circulation base state.

I trust the expertise of the appropriate meteorological agencies to alert the public of additional weather hazards worldwide, including official statements for tropical cyclones that are likely to impact regions such Madagascar week-1. Locations farther east including northern Australia will have an increased tropical cyclone risk weeks 2-4. Portions of particularly Western Europe may have several rounds of intense/severe wind and rain during the next couple of weeks.

Appendix

Links to CPC and PSD ENSO discussions:

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml