Precipitation chances return today and the active weather pattern will persist through the weekend with periods of heavy mountain snow and mountain travel impacts. Very cold lows expected Thursday morning.
Discussion
Partly to mostly cloudy skies cover interior NorCal early this morning. Southerly breezes are also beginning to pick up ahead of the approaching front. Current temperatures are considerably milder (5-15 degrees in most areas) compared to 24 hours ago and range from the 20s and 30s in the mountains, to the 40s to around 50 in the Central Valley. Satellite and radar show incoming frontal system moving through northwest California early this morning. This system will weaken as it moves to the south bringing a quick shot of precipitation and gusty wind to the region today. QPF will be less than 0.10″ in the valley, and less than 0.50″ in the mountains. 1-3 inches of snow will be possible at the pass levels in the Sierra with local amounts up to 6 inches over the peaks. Travel impacts are expected to be mostly on the minor side.
After a brief break later today and this evening, the second frontal system will move in later tonight and Wednesday bringing heavier amounts of precipitation, lowering snow levels and gusty wind. QPF will still be relatively light in the valley (less than 0.25″), but heavier over the mountains (0.50″ to 1.50″) compared to today’s system.
Travel impacts are expected to be major on Wednesday with 1 to 2 feet of snow falling in the Sierra, and gusty wind resulting in low visibility in blowing snow.
The second system clears out Wednesday evening setting the stage for another very cold night into Thursday morning. Minimum temperatures in the single digits will be possible in the mountains with mid 20s to lower 30s in the Central Valley. Dry weather predominates Thursday into most of Friday ahead of another system expected over the weekend.
Extended Discussion (Saturday through Tuesday)
Pacific storm moves through Saturday bringing widespread wetting rain, mountain snow, and gusty wind. Snow levels are initially around 3000 to 5000 feet early Saturday, rising to 4500 to 6000 feet Saturday afternoon/night. Lingering showers/snow showers possible into early Sunday, mainly over the mountains.
Drier weather then returns Sunday into Monday as high amplitude upper ridging builds inland.
Forecast uncertainty increases Tuesday as models diverge on solutions. NBM increases POPs Tuesday while EC spreads precip inland Tuesday night and GFS maintains upper ridging through midweek. Ensembles/clusters lean toward upper ridging solution.