“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.
This discussion will be limited given time constraints. The 91-day signal to noise ratio (snr) anomaly composites are now updated daily, centered on the date shown. Please see product descriptions. Part-1 of WB (2008), where the GWO is formally introduced, is in press for publication in MWR. Please see link in Appendix.
SSTs have cooled across the equatorial
http://www.cdc.noaa.gov/forecast1/IndoPacific.frcst.html (note the initial projection)
A large amplitude subseasonal event, the strongest since at least last May, involving multiple time scales is in progress. Since the start of this month, the WB (2008) measure of the GWO has done a good 2 sigma orbit in phase space, reaching octant 4 about a week ago. As I type the GWO (updated through 22 October) is collapsing toward octants 8-1. The WH (2004) measure of the MJO (through 23 October) has ~2 sigma projection in octant 4 of phase space. However, that projection increases to roughly 2.5 standard deviations in octant 3 retaining the ENSO signal (more realistic).
Per full disk satellite imagery and animations of upper tropospheric daily mean vector wind anomalies, phases 3-4 of both the GWO and MJO snr composite 250mb psi anomalies nicely depict the global circulation. There is strong meridional symmetry of zonal mean zonal wind anomalies, including anomalous midlatitude ridges.
The eastward shift of tropical convection from the Indian Ocean into Indonesia, working dynamically with coupled processes involving the surface torques, poleward AAM transports and extratropical eddies have attempted to shift the atmosphere away from the La-Nina attractor. In fact, global relative AAM recently spiked to a slightly positive anomaly. However, there has been a greater removal of anomalous zonal mean easterly wind flow from the subtropical atmospheres than actually adding westerlies. Having my reasons, analogous to recent failed financial stimuli to save the on-going collapsing global stock markets, the same may be true for the atmosphere.
There is no change to my speculative outlooks from past discussions. My confidence would be higher if I was doing this writing a month from now given seasonal cycle issues. For example, meridionally directed Rossby wave energy dispersions (RWDs) forced by west Pacific Ocean tropical convection
Observational evidence suggests a quasi-stationary component of the tropical forcing (~90-130E per OLR time sections)/global circulation anomalies may be emerging. However, going along with the GWO (keeping in mind rapid variations), I do think it is probable there will a signal of tropical forcing propagating first into the west central Pacific, then Western Hemisphere by roughly week-3, perhaps sooner (noise understood). Hence an evolution of anomalies shown by phases 3-5 of both the MJO and GWO composites of snr 250mb psi anomalies is probable weeks 1-2. A “jump” to phases 7-8-1 circulation anomalies shown by particularly the GWO composites may be reasonable weeks 3-4. The latter suggests anomalously strong troughs to impact the western
Internationally, intense to severe thunderstorm clusters will continue to impact the Bay of Bengal 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. There has been an increase during the last week, including locations such as
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:
We hope additional overlapping seasonally varying global and zonal mean subseasonal composites for variables such as surface air temperature, precipitation, geopotential height, winds and streamfunction anomalies can be posted on the ESRL/PSD GSDM web site. Part-2 of our 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 complete discussion the weekend of 31 October-2 November.