Friday, February 20, 2009

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.

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. (note the initial projection) (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.


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):

The following are links to information about the stratosphere and other nice monitoring tools: (new stratosphere link!)

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

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

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:

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


snoman said...

Hi Ed,

Looking at the latest reanalysis maps I see there has been an average 250 meter positive height anomaly over the Pacific at 40N 165W so far for the month of February. What would have to change for that to move to around 150W. This has certainly turned into a frustrating winter for fans of snow and cold weather in Pacific NW. Certainly not what one would expect with cold ENSO.

Thank you!


Ed Berry said...

Hi Jim,

Actually, if you look at phase 3 (La-Nina like) of the GWO snr psi composite anomaly plot, that suggests a ridge ~165W. However, these are just composites, and during individual cold event years the ridge can be farther east and amplified (at least periodically). We saw that last December, and a good example is 1996-97, when subseasonal activity was strong. The latter has generally not been the case for the 2008-09 boreal winter.


JordanWeather Forecasters Team said...

Hello Ed,
Hope you are fine.
I know that you are busy. But I want to inform you, that February just keeps blasting us with storms!!

Storm passed us by Saturday, and still affecting us, and brought very high "needed" amounts of rain for much of the Middle East. Also, we had intense thunderstorms activity, hail storms, and some snow over high mountains.

Models are showing an incredible deep upper-level trough on next Friday along with very deep surface low pressure, hopefully will bring stormy conditions again to the Middle East, although the snow possibility is low as the surface pressure very low (no good thickness), but some high areas could get snow by early Saturday.

Also ECMWF, is showing an amazing storm on next Monday (hopefully a snowstorm), I will keep you updated.

What is your thoughts about March for my area, models is pointing up an ridge over Atlantic, so we could see another time (long-last) ridge over the Middle East??


Ed Berry said...

Hello Moh'd

Thank you for the update! I have been out in Boulder, CO, giving a GWO workshop with my colleague, Klaus Weickmann. It has been very difficult for me to keep up with the current situation the last few days.

However, the quasi-stationary La-Nina base state is well established. The troughs have been digging into roughly the central Mediterranean then moving east. There may some retrogression of that situation during the next 1-2 weeks.


Captain Climate said...

It seems that popular mainstream opinion is to jump on the El Nino bandwagon without a mechanism to get us there. If I can growl a little bit on behalf of your Rottweiler ... saying "it is time for an El Nino" is not good enough for me.

Thanks for standing your ground and sharing actual data and your analysis with us. Unless the mechanism for cooling stops or extratropical forces combine to induce a longer term countertrend rally than what we have seen ... then pure scientific method (null hypothesis) would lead us first to a La Nina/Low AAM regime is in a reloading phase.

It will be interesting to see if Redoubt blows or other vatiables introduce exciting variations to the global circulation.

Thanks always Ed!