“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.
The 91-day signal to noise ratio (snr) anomaly composites are being updated daily. There are still some map room issues that will hopefully be resolved soon. 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.
These discussions are part of an experimental effort involving linking weather and climate. We are moving forward on having a one-day workshop in
The warmest ocean waters globally extend from central
Responding to the global atmospheric circulation, basin-wide cool SST conditions have been observed for at least the past month across all Nino regions. A recent disruption of the trades across the west central
http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)
The wind and convective signals have shown some evidence of getting into sync during the last few weeks, as have the tropics and extratropics. However, they are still not lined up (GWO octant 1 verses MJO octant 4 in phase space – discussed below), and the interactions are exceptionally complicated. The dynamics of these processes are too difficult to discuss (at the level we are comfortable with) in a medium such as a blog. Only a few highlights are given in the following, and relevant material presented in my last few postings will not be repeated.
As was anticipated from monitoring the dynamics explained by the WB (2009) measure of the GWO (loosely stated), moist intense tropical convective forcing has reasonably consolidated ~0/110E extending from the southern Arabian Sea east-southeast into northern
Retaining the interannual and ENSO signals, there is ~1 sigma MJO projection in octant 4 of WH (2004) phase space. In fact, phase 4 of the WH (2004) MJO snr 250mb psi composite anomaly plots reasonably depicts the current global tropical circulation. However, in my view there is currently no real coherent MJO signal of tropical convective forcing. We are observing a quasi-stationary La-Nina like component of the global ocean-land-atmosphere system. Furthermore, any notions about an active MJO signal in the west central Pacific are simply incorrect. A few techniques and tools suggest the latter. This type of misinterpretation serves as an example of what results when care is not taken to understand the dynamics of fundamental atmospheric processes including monitoring constant everyday non-linear interactions (yes, the Rottweiler is barking)! An overview and simplified brief attribution of “what recently happened” is given in the following paragraph.
Animations of various daily mean vector total and anomalous wind fields for the last 1-2 weeks do suggest strong tropical-extratropical interactions especially across the
Through 11 December the WB (2009) measure of the GWO had ~1 sigma projection in octant 1 of phase space. However, this data point is along a recent trajectory having a magnitude of 3 sigma at times. Making use of this GWO variation along with the 250mb snr psi composite anomaly plots (phases 7-8-1), this was one very important consideration to anticipate several weeks ago (before the models and official forecasts) the on-going retrogression of PNA circulation anomalies leading to a western USA trough. Additionally, the excursion toward “high AAM” has been the largest this year, and part of a trend to increase global westerly wind flow since March. Identifying the latter was one of my reasons when I suggested several months ago that while boreal cold seasons 2007-08 and 2008-09 may have similar circulation characteristics, an important difference may be greater zonal mean subtropical westerly wind flow this winter. So far, this speculation has been correct.
Global relative AAM has dipped to slightly below the R1 data climatology while its tendency remains weakly negative. Recent significant anomalous zonal mean westerly wind flow in the subtropical atmospheres has largely been removed through frictional dissipation especially across the
Phase 1 of the GWO 250mb snr psi composite anomaly plot best represents the extratropics. I still do think coupling in ~GWO and MJO phase 3 (La-Nina) is a possibility during the next few weeks, with perhaps variations in ~phases 3-5 for several weeks going into 2009. Loosely that translates to central/eastern Pacific Ocean ridging with western and central
The role of the anomalously warm Australian and southwest Pacific Ocean SSTs for the
Internationally, the focus for intense to severe tropical thunderstorm activity is probable to continue across the
The tropical cyclone hazard for both the west central
I trust the expertise of the appropriate meteorological centers to alert the public of additional weather hazards worldwide. For instance, anomalous cold Arctic air is finally building up in both Siberia (surface temperatures ~minus 70F) and western
Links to CPC and PSD ENSO discussions:
The following is a link to information about the stratosphere and other nice monitoring tools:
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)), has been accepted for publication MWR. A pdf of the in press version can be downloaded from the
In addition to the subseasonal snr composite anomaly plots, we hope near real-time discussions with “weather maps” will 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 a discussion the weekend of 19-21 December.