November 23, 2020 – Light showers possible over the mountains on Wednesday, otherwise dry weather expected into the weekend. Mild days and cool nights will continue with occasional breezy north to east winds.
Discussion
Strong vort dropping southeast through the Bay Area and Sacramento region early this morning with radar indicating a few showers continuing south of I-80. The remainder of the region is under clear to partly cloudy skies. Current temperatures are milder compared to 24 hours ago and generally range from the 20s and 30s in the mountains to the 40s across the lower elevations.
Trough drops southeast toward the Lower Colorado River Valley this afternoon as short-wave ridging builds into NorCal. Surface pressure gradients re-tighten with locally breezy north winds expected to develop across the Central Valley late in the day. North and east gradients max out early Tuesday with local gusts of 25-35 mph possible in the wind-favored areas along the western edge of the Sacramento Valley, and over the foothills of far northern Sierra and southern Cascade Range.
Next upstream trough forecast to brush the region Tuesday night and Wednesday bringing another chance for light precipitation across the northern mountains and northern Sierra. Dry weather returns for Thanksgiving and late-week with another round of breezy north to east winds expected.
Temperatures will be close to average for late-November.
Extended discussion (Friday through Monday)
Upper ridging builds over the area Friday and axis gradually moves through over the weekend. This will result in dry weather with high temperatures slightly above normal. Locally gusty north to east wind possible in the foothills and mountains Friday morning. Deterministic models differ Monday with ECMWF bringing next Pacific frontal system inland, while GFS maintains upper ridging over NorCal. Ensemble solutions favor ECMWF so forecast has a threat of showers on Monday, mainly over the coastal and northern mountains.