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

“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.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 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

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 (3^rd 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 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

“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.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 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

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.

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://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 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 unscientific!

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

Ed Berry

Update from the Depths of Circulation Hell

“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.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 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://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)), 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 unscientific!

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

“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.pmel.noaa.gov/tao/jsdisplay/

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)

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

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://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)), 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 unscientific!

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?

“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???

“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