Cold Windy System Approaching West Coast Tonight….Highlights are wind and cold with light snow….Split flow pattern brings a lot of uncertanity to Sunday/Monday Storm….
Tuesday November 15, 2016
Posted at 2:17 pm by Howard
Forecast remains the same as a windy system approaches tonight…..It will be a lot colder Wednesday and even colder Thursday because of the chilly NW jet on the Trof back side. The current extension of the East Asian jet comes without much in the way of moisture for Central CA. The wave length between the eastern pac ridge (EPAC) and the ridge down stream is counter productive for the Sunday night storm. Thus the upper Trof being negative tilt will tend to split southward with the possibility of LA or even San Diego doing better with that storm. Some models have a more decisive split then others. So this is a case where any confidence in the numbers will have to wait until Thursday or Friday most likely. In that it is Mid November, Winter is beginning to set in hemispherically. So far winter has set in fully over Northern Europe and Northern Asia. In the next 3 weeks Winter will come to North America and our season of transition will be over.
The teleconnections all have the Arctic Oscillation rapidly going negative over the next two weeks. This means that the upper flow will become more meridial in nature with high latitude blocking setting up with the westerlies undercutting here and their. This eventually brings the cold south into the States. (CONUS) So this is the question; Will the -AO favor the east or western US. I think both with the west first and then the east. We’ll see. As blocking develops, that should eventually take care of the problem of the west coast split.
I will have an update on Precip for the central sierra Thursday morning in my letter….:-)
For what ever it is worth….Those that are concerned about a good snowpack for Christmas might like to know that the 46 day, Day 0-46 or from 00z 14th of NOV to 00z Dec 30th; The ECMWF EPS ENS is showing a lot of snow for the Northern Sierra south through the bottom of the Southern Sierra with amounts of 150 inches suggested by the guidance.