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 currently centered on 10 November due to technical issues. This should be resolved soon meaning resumption of daily updates, and will have minimal impact on these assessments. Please see product descriptions. WB (2008), 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.
Remember that these discussions are part of an experimental effort linking weather and climate. Until this work is formalized at the national level, many important scientific issues we are easily well aware of cannot be addressed. Stated another way, it is nearly impossible for me to talk about “everything” in these postings. Also, there are tentative plans to have a one-day workshop on the WB (2008) GWO concepts ~February 2009 in
The warmest SSTs globally extend from southern
Yes, we understand the subsurface issues and the concerns raised by the PDO crowd, latter measure projecting on an extreme negative phase. Regardless, there is always constant interaction between the global atmosphere and SSTs. The global tropical SSTs contributed to forcing the atmosphere into the low AAM side of GWO phase space (La-Nina characteristic) perhaps as early as December 2006. With variations, this has not changed. Currently, the equatorial central and eastern Pacific Ocean SSTs are responding to a global circulation state favoring coolness in those regions. This is why measures such as Nino 3.4 to define “ENSO neutral” have limited scientific defensibility, let alone basing seasonal forecasts on them.
Referring to my title, just like the 1974 Ali-Foreman fight when the former did not dance after round 1, I am not clowning around with phrases such as “El-Viejo”, “witch”, “Rottweiler statements”, etc. for this discussion. The earth is not flat, center of the universe, etc., meaning care should be exercised thinking that any weather-climate phenomena such as ENSO has to follow a "classic cycle" (ex., Rasmussen and Carpenter (1982)). While encore events tend to be weaker (there are very important sample size issues), everything I and others understand tell us, from the global ocean-land-atmosphere perspective monitoring subseasonal variability, La-Nina is back.
http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)
The subseasonal global circulation variability leading to the above appears that it will have significant implications for world weather including the
Tropical convective forcing is currently centered ~5N/100E extending from the southeast Arabian Sea to north of
The large variation of the WB (2008) measure of the GWO is currently the most robust weather-climate signal. Global relative AAM (plots updated through 20 November) is ~1 standard deviation (1 AMU) above the R1 data climatology, working with ~ plus 40 Hadley positive global tendency. The former may be the highest since about a year ago.
The astute reader may now ask how this can be if I am arguing La-Nina is back. Of course, given that the GWO is red noise (stochastic), with the large signal "something else" can happen meaning the point of this whole discussion (La-Nina) may be a poor assessment on my part. However, since I think we are seeing a repeatable event (more said below) within an emerging quasi-stationary La-Nina base state, odds are with me. Time will tell. What the large GWO signal means is global westerly wind flow has increased, much of that occurring in the subtropical atmospheres where 200mb zonal mean zonal wind flow anomalies are ~2-5m/s. The dynamical processes contributing to this have come from the global surface torques, with the mountain ~plus 30 Hadleys and frictional ~plus 20 Hadleys.
This is the point where a real-time live discussion with “maps and plots” is needed. In a sense, a repeatable variation of the 3sigma October GWO orbit in phase space is in progress. Much of the positive frictional torque is coming from the extratropics linked to poleward and downward propagation of anomalous upper tropospheric zonal mean easterly wind flow. I can also link the components of the current positive clustered mountain torque to this. All of this has involved coupled complicated interactions with tropical-extratropical Rossby wave energy dispersions (RWDs) interacting with the baroclinic eddies. At times, during the last several weeks, there have been well defined projections onto a positive phase of the Branstator (2002) circumglobal teleconnection (anomalous midlatitude ridges). Bottom line, the global wind signal is dominating the tropical convective forcing.
Since at least mid September there has been a strong zonal asymmetry of tropical upper tropospheric circulation anomalies consisting of twin
Regionally, a synoptic response across the Asia-North American sector is the extending
Consistent with a complete forecast process, models such as the ESRL/PSD ensemble and recently the NCEP/GEFS into early week-3 are starting to catch on. I am concerned the largest negative surface air temperature anomalies may be shifted farther west (linked to Indian Ocean forcing) toward the
Loosely, December renditions of phase 3 (not available on-line, yet) of both the GWO and MJO 250mb snr streamfunction composite anomaly plots may represent next month. Of course, unpredictable rapid variations in GWO phase space will occur. In any event, I respectably offer that the official
Weather ramifications have already been suggested. The extended North Pacific Ocean jet/split flow pattern across the
Weeks 1-2 for the tropics are also per above. There is a strong westerly wind event from the central Indian Ocean into
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. Active regions have been occurring during the last week, including the cold and stormy situation around
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 (2008)), has been accepted for publication MWR. A pdf of the in press version can be downloaded from the following link:
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 29-30 November.