Upper Low Now Moving South through the Pacific NW will increase breezes this afternoon with a upper winds becoming easterly by Sunday….Some light snowfall expected……Warming trend later next week with the eventual return of low 70s by next weekend end….
Saturday October 3, 2015
Posted at 1:27 pm by Howard
The Forecast models are in good agreement in bringing a closed upper low south from the Northern CA coast then SE along the coast line or just inland over Ventura County. It then is expected to shift east Monday….
The majority if the precipitation will be over the Southern Sierra Near Mount Whitney. Over a foot of snow is possible there. The other area that is under the gun is over the White Mountains and the mountains around Death Valley.
Closed lows of this type are difficult to predict, precipitation wise, as there is not a true active front that comes through. It is rather an area of surface, mid or upper level convergence called a deformation zone that will come through Mammoth Sunday morning, and part of the afternoon. This deformation zone will shift south with time and may stall out over the southern sierra. Where it stalls is the area with the most precipitation expected. In this case the upper low is forecasted to shift east through the Mojave Desert and so the deformation line will slow and pivot over the Southern Sierra and Owens Valley. Mammoth should receive at least 2 to 4 inches of Snow, Sunday into Monday at and above 9,000 ft.
However, this system has a convective element to it, and should a thunderstorm develop over night or in the Morning, several more inches is possible; even at lower elevations. Otherwise, over the lower elevations 7000 to 8000 feet, there will be snow pellets and brief snowfalls possible. For those in the back country, be prepared for cold wet conditions with at least a light snowfall, in the 2 to 6 inch range.
Dr Howard and the Dweebs……………………………….:-)