Friday, December 09, 2005

The Devil is in the Details

In essence, still on track with previous 2 postings. The anomalously intense polar jet across the western Pacific (winds in excess of 80 m/s) continues to move east, and appears the brunt of these winds will move northeast toward WA/BC during the next few days as most models suggest (along with the precipitation). The STJ should also stay in place (part of the split flow off the USA west coast), and the closed low currently along that jet west of CA should come into the southwest states by around Monday of next week.

As the retrogression of the ridge position take place early next week (linked to the tropical convective forcing across Indonesia and the Indian Ocean; this convection does not project onto a MJO), I think the notion of coupling of the northern and southern branches of the westerlies across the Rockies and Plains looks good (as also shown by most models -- now). This does suggest baroclinic storm development and another surge of cold air. I also like the solution offered by the CDC ensemble of a stronger low latitude closed low breaking through the ridge onto the CA coast by late next week, and coupling with yet another digging northern branch trough. At that point, on the order of next weekend, we may see an anomolous very large amplitude ridge from ~30N/135W extending northward well into the Arctic with more storm development across the Rockies and Plains. Later during week 2 into week 3, given the stationarity of the tropical convective forcing and other matters, yet another transient low latitude jet streak/development scenario may be probable. I think this cold regime is going to remain in place for a large part of the country for at least the next couple of weeks, with the emphasis seemingly on the central USA.

For the DDC CWA, in terms of precipitation, I suspect impacts from this first (~ Tuesday) storm will be just to our north and northeast. However, I would be concerned about the second storm being not only stronger, but farther south, for next weekend. In any event, need to monitor.

Ed Berry

1 comment:

Jackson said...

Just to be clear the Tuesday storm that would be northeast of the DDC area is Tuesday Dec 13th, and the "weekend" storm would be the period from Dec 17th thru the 19th?