Cool and unsettled weather is expected through much of the week with shower and thunderstorms chances. The higher elevations will see some late-season accumulating snow.
Cold closed upper low is centered near the Bay Area early this morning with scattered showers now covering most of interior NorCal. Some light snow is occurring over the high Sierra, but traffic cameras indicate wet road surfaces so far given the recent mild temperatures. We’re still seeing some local southeasterly to southerly wind gusts of 15-25 mph across the region. Current temperatures range from the upper 20s and 30s in the mountains to the upper 40s to mid 50s across the Central Valley.
The cool and unsettled weather will continue today into tonight with scattered showers as the low remains centered near the Bay Area. Valley locales may see a tenth to a quarter inch of rain from passing showers and thunderstorms while the mountains may see up to half an inch.
Snowfall near the crest of the northern Sierra may amount to around 3 to 6 inches over the next 24 to 36 hours, but snowfall rates will likely remain low enough to limit much accumulation on road surfaces.
There will also be potential for a few thunderstorms this afternoon and evening, and forecast soundings indicate sufficient instability for some stronger storms accompanied by small hail.
The low is forecast to drift further south the second half of the week with shower chances mainly retreating to the NorCal mountains. Temperatures will moderate a bit beginning Wednesday, but will still be around 10-15 degrees below average.
Extended Discussion (Saturday through Tuesday)
Ensembles and clusters show good agreement in another trough from the Gulf of Alaska keeping temperatures below normal through the weekend into early next week. The further north track of this system suggest the best potential for precipitation will be over the mountains of Shasta County and western Plumas County/Lassen National Park.
The NBM projects rainfall amounts through Monday of a tenth of an inch or less in the Valley, highest around Redding. The mountain totals range from around three quarters of an inch over the Shasta County mountains to around a quarter of an inch over the northern Sierra.
High temperatures gradually trend upwards from the weekend into early next week, but still remain below normal for this time of year. Valley highs for Tuesday are forecast to be in the mid 70s.