Unsettled weather continues into the weekend as an anomalously cold system brings showers, isolated thunderstorms, breezy winds and mountain and upper foothill snow. Drier and warmer weather returns next week.
Discussion
Showers and a few thunderstorms continue in the Sierra early this morning from about I-80 southward as the cold front moves into central California. Snow levels have come down enough that chain controls have been posted across Donner Pass. Further north, a few showers associated with the incoming upper low have redeveloped over Shasta County.
Otherwise, partly to mostly cloudy skies cover the region along with locally breezy south to west winds of 15-30 mph. Current temperatures are considerably cooler (5-15 degrees) compared to 24 hours ago and are in the 20s and 30s in the mountains, and mainly in the mid 40s to lower 50s across the Central Valley.
Cold and unsettled weather is expected across the region through Friday as the cold upper low settles over NorCal bringing scattered showers, a few thunderstorms, periods of moderate to heavy mountain snow with lowering snow levels.
High temperatures will be much cooler the next several days, around 20-30 degrees lower compared to earlier in the week. Overnight lows will also be cooler with some patchy frost possible in a few foothill areas Friday and Saturday mornings, especially Saturday as clouds and showers are ending.
QPF is generally unchanged the next 48 hours with 0.75″ to 1.50″ inches expected over the mountains (except up to 2.00″ in the Sierra of Tuolumne County) with less than 0.50″ in the Central Valley.
The convective nature of the system may lead to some wide QPF variations locally.
Snowfall amounts of 6-12 inches are forecast in the mountains above 4k ft, especially in the Sierra south of I-80. Local amounts of 18-24 inches will be possible across the higher peaks.
Lighter snowfall accumulations will be possible down into the upper foothill elevations tonight and Friday morning as snow levels drop down to around 2000-2500 ft.
A Winter Weather Advisory remains in effect through Friday evening for difficult travel conditions.
Drier conditions return to the region later on Friday and into the weekend as ridging begins to return. A few mountain showers will be possible on Sunday with a passing short-wave trough. Otherwise temperatures will moderate slightly over the weekend.
Extended Discussion (Monday through Thursday)
Upper ridging in EPAC Monday builds inland over interior NorCal and remains dominant synoptic feature through the extended period. This will result in dry weather with a warming trend.
Above normal temperatures expected with NBM forecast highs in the Central Valley around 80 by Wednesday and lower 80s Thursday, about 10-15 degrees above normal. Locally gusty north to east wind possible Monday into early Tuesday.