Burn the Cookbooks!!!

“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 general thought is “ENSO neutral conditions with some lingering effects of La-Nina circulation” for at least the next few months. While in the views of many there is some truth to a statement such as the latter, care must be taken not to overlook the always important details of the subseasonal dynamics (which do impact seasonal outcomes). For instance, one response has been the warming of the equatorial east Pacific Ocean during the last several months, perhaps reflective of a “~year (-1) of a Rasmussen and Carpenter (1982) warm event scenario”. Please see links below, and stay tuned.

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

As expected, Eastern Hemisphere tropical convective forcing has become quite intense, currently centered ~5N/100E. Most numerical and statistical MJO prediction schemes did a poor job with this evolution. Reasons include a failure to capture the role of extratropical dynamical processes explained by the WB (2008) GWO. Continuing, there was also difficulty for many week-2 numerical ensembles to predict the extratropics, with the ACC of the NCEP GFS dipping well below zero for the North American sector. The latter are well known issues by WB, and hopefully an opportunity will arise to quantify it statistically.

Three-day averaged OLRA have exceeded minus 90 W/m**2 with the Indian Ocean severe thunderstorm clusters. The area of enhanced tropical rainfall is oriented northeast-southwest, not only enhancing the monsoon systems, but also frontal bands even across southeast China. Per WH (2004) phase space diagrams, there is a less than 1 sigma MJO projection in octant 3. Leaving the interannual component in, the projection is greater than 1 standard deviation, which is more realistic. I do expect this tropical forcing to continue propagating east and north during the next 1-3 weeks.

During the last couple of weeks there has been some attempt to rejuvenate our low AAM base state. Leaving the westerly QBO phase in, global relative AAM dipped to roughly 1 AMU below the R1 data climatology earlier this month. With the classic transition of Eastern Hemisphere tropical upper tropospheric circulation anomalies to Indian Ocean (west Pacific Ocean) anticyclones (cyclones), equatorial Pacific westerly wind flow anomalies have appeared (roughly 20-25m/s around the date line). Particularly for the Southern Hemisphere, there has been poleward propagation of zonal mean zonal wind flow anomalies including easterlies shifting into the subtropical atmospheres.

These are only a handful of many reasons why global relative AAM tendency spiked to ~plus 20 Hadleys forcing the WB (2008) GWO into approximately octant 4 of phase space on 20 July. Both AAM tendency and the GWO are headed back down (through 21 July), and whether the rejuvenation discussed above is a longer term signal remains unclear (not to contradict other weather-climate signals).

Broadly, there continues to be good tropical-extratropical coupling, including interhemispheric meridional symmetry of zonal mean zonal wind anomalies favoring anomalous midlatitude ridges. Comparing recent daily mean 150mb vector wind anomalies to the MJO composites, phase 3 of 250mb psi is loosely representative (“apples and oranges” issues understood). For instance, there is a well defined Rossby wave energy dispersion (RWD) signal from the west Pacific Ocean cyclones that links up the trough-ridge-trough pattern across North America.

The careful reader will also see these signals in the GWO composites. Avoiding more length and confusion, there is ~50 day period between the recent minima in the time series of the global frictional torque. This leads to the point that decay time scale processes explained by the WB (2008) GWO are currently at least as equally important as any MJO contribution. Hence my feeling (one reason) why the notions suggested by the phase 3-4 composites of the GWO may be representative for roughly weeks 2-3. We need to remember these composites are still centered on 1 July (should be updated soon), and that using these must be defended on sound scientific reasoning, not “shoe horned”. In any case, this thought is consistent with my discussion posted on 12 July.

For the North American sector, perhaps ~days 10-20 (roughly 2-13 August) ridge amplification off the west coast into Alaska leading to an approximate reversal of circulation anomalies across the USA is a possibility. My confidence in this scenario is not high; however, I feel it should be “put on the table”. There is little suggestion of this scenario from the models and certainly the official USA week-2 forecast. In fact, the suggestion of warmth officially across the northern states is also inconsistent with the MJO signal. The "meteorological reasoning" for the official week-2 forecast is based on seemingly subjectively blending various models, including deterministic runs (my dog (angry Rottweiler) does not like this!).

The probable USA temperature patterns can be seen from the 2m air composite signals. However things pan out, a shift toward below normal air temperatures from the Great Lakes extending southward toward the Central Plains should be considered. Once again, locations periodically focusing on the Northern and Central Plains into the Ohio Valley are the most probable storm track for MCS activity. Other locations possibly impacted by periods of heavy rainfall and severe local storms are portions of the eastern states.

Intense to severe tropical thunderstorm activity should shift east and north through portions of India and Southeast Asia during the next 1-2 weeks. Included are frontal bands across southeast China. By week-3 the most intense tropical convection may focus on the northwest Pacific Ocean including the South China Sea and the Philippines. The tropical cyclone hazard may also increase for these areas. Whether or not convection also propagates eastward along the equator to near the date line is unclear (may cause an equatorial westerly wind burst). The tropical cyclone hazard for the Western Hemisphere should be diminished weeks 1-2 (hybrids always understood, including the one currently northeast of the Philippines).

Please see the latest official tropical cyclone forecasts for all basins. I trust the expertise of the appropriate meteorological centers to alert the public of additional weather hazards worldwide.

Appendix

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. In addition, the first of a two-part paper has been submitted to MWR where WB formally introduces the GWO. A pdf version can be downloaded from the following link

http://www.cdc.noaa.gov/map/clim/wb08_final.pdf

Overlapping seasonally varying subseasonal composites for variables such as surface temperature, precipitation, geopotential height and streamfunction anomalies are planned on being posted on the web site mentioned above and presented in part-2 of our paper. 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!

Given shift work and travel, updates are extremely difficult. I hope to do another discussion around the weekend of 2-3 August.

Ed Berry

Another Weather-Climate Crossroad

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

Following the lead started last week, 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

Below are the links to various sources of global SST information. Overall, any interannual component of variability involving the SSTs is still unclear. There are some aspects similar to a year ago appearing such as the loose spatial pattern of anomalous warm-cool-warm of equatorial/tropical SSTs from the Indian Ocean into the west central Pacific Ocean. There has been little change since at least 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/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

Full disk satellite imagery and other tools used to help understand evolutionary processes still indicate multiple regions of enhanced tropical convective forcing. Similar to a week ago, they include the equatorial Indian Ocean into the Eastern Hemisphere monsoon systems and the eastern Pacific Ocean ITCZ into the Americas. Some important differences, however, are increased suppression over the west central Pacific Ocean and a significant increase in coverage and intensity along the equator over the Indian Ocean. In fact, latest 3-day averaged OLRA for the latter are ~minus 70-90 W/m**2. This increase of Indian Ocean forcing was expected a week ago, linked to the dynamics of complicated Rossby wave energy dispersions (RWDs) arcing through the extratropics, particularly the Southern Hemisphere (more said below).

As I have been also expecting to happen for at least the past 2 weeks, global relative AAM is decreasing. In fact, ~7 July the calculated relative AAM tendency was ~minus 30 Hadleys. This was one of the largest negative magnitudes since December 2007. In contrast to the computed tendency (GWO2), the latter takes into consideration the zonal mean AAM transport signal. Updated through 10 July relative AAM was roughly 1 AMU below the R1 data climatology with the calculated tendency of ~minus 10 Hadleys.

While not feasible to discuss the details here, from daily monitoring and working to have a better understanding of the dynamics involved, I feel fairly comfortable offering attribution to this recent AAM behavior. Much of this removal of global westerly wind flow has been through frictional dissipation of poleward and downward propagation of zonal mean westerly wind flow anomalies into the midlatitude storm track regions for at least the past several weeks. That has been especially true of the Southern Hemisphere, given austral winter, having zonal mean negative frictional torque anomalies of more than 2 Hadleys ~50-60S contributing to a global frictional torque of ~minus 20 Hadleys around 1 July. Interesting question to ask is if this behavior is a loose mirror image to what occurred last February for boreal winter? The point is this type of understanding helps to anticipate subseasonal behaviors including the MJO, as part of the GWO. All numerical models will do generally poorly with these types of processes even after a few days into their prediction cycles.

Updated through 10 July, both the WH (2004) and WB (2008) measures of the MJO and GWO respectively had similar locations in phase space. Both were in approximately octant 1 having projections greater than 1 sigma. I think there is good coupling between the tropics and extratropics, including (again) arguably meridional symmetry of zonal mean zonal wind anomalies. As bands of zonal mean westerly wind flow anomalies shift poleward through the extratropical atmospheres, easterly wind anomalies are increasing in the tropical and subtropical atmospheres. This all goes “hand in hand” with the MJO dynamical signal of tropical convective forcing starting to return to the Eastern Hemisphere, particularly the Indian Ocean.

Referring to the GWO and MJO composites for ~250mb streamfunction (psi) and 2m air temperature, the ongoing progressive synoptic trough currently in the central USA and the model predictions of another for the USA Pacific Northwest are consistent with roughly phases 1-2. Most week-2 ensembles were predicting the current trough to dig into the western USA, which did not occur (another issue).

While unclear about the time scale, I do think the spatial patterns depicted by especially GWO phases 3-4 is where the global circulation is going. My suspicion for the latter is ~weeks 3-4 (by early August). Until then, the patterns illustrated by MJO phases 2-3 may be the best offering of a prediction roughly weeks 1-2. The bottom line is I still have my concerns for some rejuvenation of the low AAM base state going into the upcoming boreal cold season. Obviously exact weather ramifications are unclear. Statements like, “ENSO neutral with lingering La-Nina circulation”, while perhaps currently true, tell you nothing about the critically important global subseasonal dynamics (as measured by the GWO).

The probable USA temperature patterns per above can be seen from the 2m air temperature composite signals. Again, remember these are composites and individual cases can be much stronger. Locations periodically focusing on the Northern Plains into the Ohio Valley are the most probable storm track for MCS activity. That includes more heavy rainfall for locations such as Iowa and the Upper Mississippi Valley.

Intense to severe tropical thunderstorm activity is probable to increase from the equatorial Indian Ocean into the monsoon systems and frontal bands of India and Asia during the next few weeks. The west and northwest Pacific Ocean will remain a “wild card”, including the possibility of tropical cyclone spin-ups threatening the Philippines and Southeast Asia. The East Pacific Ocean tropical cyclone hazard should wane by week-2.

Anomalous upper tropospheric twin tropical anticyclones are well defined across the Western Hemisphere, while they slowly propagate through Africa into the Indian Ocean. This situation is favorable for additional strong African easterly waves. Please see the latest official tropical cyclone forecasts for all basins. I trust the expertise of the appropriate meteorological centers to alert the public of additional weather hazards worldwide.

Appendix

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. In addition, the first of a two-part paper has been submitted to MWR where WB formally introduces the GWO. A pdf version can be downloaded from the following link

http://www.cdc.noaa.gov/map/clim/wb08_final.pdf

Overlapping seasonally varying subseasonal composites for numerous variables including surface temperature, precipitation, geopotential height and streamfunction anomalies are planned on being posted on the web site mentioned above and presented in part-2 of our paper. 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!

Given shift work and travel, updates are extremely difficult. An update is unlikely next weekend, 19-20 July. I hope to do another discussion ~23 July.

Ed Berry

Reprisal -- Is the Witch Dead???

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

I am going to work to make these postings shorter and focus more on the products contained in the experimental dedicated web page that is only in the infancy of development, per Appendix in previous discussions. One important purpose of these discussions is to provide a much needed climate service for all users. The web link is

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

To keep us “vigilant” about the interannual variability component, I will leave the following links in. While there has been a bit more respectable warming of equatorial eastern Pacific Ocean SSTs (~ plus 3-4C anomalies at 50m depth) along with other measures suggestive of a possible eventual evolution toward an El-Nino, I think the interannual signal remains unclear. I will give attention in these postings should that change. Please remember that “ENSO neutral” does not at all imply there will be a lack of robust subseasonal events leading to global high impact weather situations.

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

Full disk satellite imagery etc. indicates multiple regions of enhanced tropical convective forcing. These include the Eastern Hemisphere monsoon systems into the northwest Pacific Ocean, the Eastern Pacific Ocean ITCZ through the Americas and the western Indian Ocean. Complicated interactions with the extratropics have resulted in this pattern, and can only be understood with rigorous daily monitoring utilizing the WB (2007) GSDM. In any case, a strong MJO projection in octant 1 of ~2 standard deviations in WH (2004) phase space, with the very important interannual base state left in, has resulted. To me, this is still MJO #6 since boreal fall 2007.

Updated through 2 July, there is little circulation projection in the WB (2008) GWO phase space. However, this phase space depicts a dynamical evolution of the global atmosphere (not static!!! --- insert angry Rottweiler). For instance, as part of several attempts to increase westerly wind flow globally since late 2007, such has been the case since roughly mid May. Bands of zonal mean westerly wind flow anomalies have been propagating poleward off the equator with downward transport (by the baroclinic eddies), only to undergo frictional dissipation in the midlatitude storm tracks. Even though the latter has recently been most robust in the Southern Hemisphere given austral winter, for the Northern Hemisphere there has been zonal mean dissipation ~20 and 50N. Hence the global friction torque is ~minus 20 Hadleys, one of the lowest values since late 2007.

The point is that I expect to see global relative AAM decrease very soon (restatement from my last posting). Relative AAM tendency is probable to become strongly negative as the global mountain torque becomes negative and a poleward transport signal develops in both hemispheres (please see description and schematic on the web page). Hence the WB (2008) GWO is likely to orbit into octants 2-3 during the next 1-3 weeks. This will again be a situation where both the WH (2004) and WB (2008) phase spaces are similar, ~2-3. Evolutions such as this may rejuvenate our low AAM base state.

Referring to the MJO composites for ~250mb streamfunction (psi) and 2m air temperature, octants 2-3 suggest an increased probability of a northwestern USA trough with a ridge across the eastern states. The 2m air temperature patterns are the expected “cool west-warm east”. Keep in mind these are composite signals, hence relatively weak. The GWO composites are similar, but show a nice progression of coolness shifting into the central part of the country and heat returning to portions of the west (still warm for much of the east). I prefer the latter and suspect phases 3-4 of the GWO will be most probable by ~week 3 based on results discussed in our submitted paper to MWR. Most models are catching on to this notion for weeks 1-2.

The precipitation patterns should be well understood. After a fairly quiet few weeks (relatively speaking), intense to severe MCS activity for much of the Northern Plains into the Ohio Valley is a concern starting next week. This activity may become particularly intense in terms of flooding rainfall weeks 2-3 while drifting slowly southward (focus on Iowa and Missouri?).

Intense to severe tropical thunderstorm activity is probable to increase from the Indian Ocean into the monsoon systems and frontal bands of India and Asia during the next couple weeks while the west and northwest Pacific Ocean stays sporadic. In fact, tropical cyclone spin-ups for the latter threatening the Philippines and Southeast Asia cannot be ruled out. The East Pacific Ocean tropical cyclone hazard should wane during week-2.

The warm north tropical Atlantic Ocean basin defied my concerns related to tropical cyclone climatology expressed a week ago with the development of Tropical Storm Bertha (was not surprised). With upper tropospheric anomalous twin tropical anticyclones returning to Africa and the Indian Ocean from the Western Hemisphere during the next 1-2 weeks, additional strong African easterly waves are probable. Please see the latest official tropical cyclone forecasts for all basins.

Other severe/high impact weather continues internationally. I trust the expertise of the appropriate weather centers to alert the public of additional weather hazards worldwide.

Appendix

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. In addition, the first of a two-part paper has been submitted to MWR where WB formally introduces the GWO. A pdf version can be downloaded from the following link

http://www.cdc.noaa.gov/map/clim/wb08_final.pdf

Overlapping seasonally varying subseasonal composites for variables such as surface temperatures, precipitation and streamfunction anomalies are planned on being posted on the web site mentioned above and presented in part-2 of our paper. 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. Relying on the numerical models alone is a cookbook!

Given shift work and travel, updates are extremely difficult. I hope to post another discussion the weekend of 12-13 July.

Ed Berry