Widespread rain, high elevation snow, breezy winds, and cooler weather return today through the weekend with the arrival of our next impactful weather system. Additional storms will be possible next week.
Discussion
Satellite and radar show the front approaching NW California early this morning. Ahead of the front, skies are mostly cloudy across interior NorCal. Current temperatures are similar to 24 hours ago with mainly 30s to lower 40s in the mountains and upper 40s to mid 50s in the Central Valley. Little has changed in the forecast with two main waves of precipitation expected over the next few days – the first with the cold front later today into early Saturday followed by a second later Saturday into early Sunday as the upper trough moves through.
Precipitation is forecast to begin over the Coast Range and Shasta County later this morning, then spread southeast reaching the I-80 corridor from the Sacramento area up into the northern Sierra by later this afternoon and this evening. Showery and cooler weather is expected Saturday, followed by an increase in showers and thunderstorms Saturday afternoon and night.
Minor to moderate impacts are expected as the system moves through bringing rain, mountain snow, gusty wind and thunderstorm chances. QPF of 0.50″ to 1″ is forecast through the valley with 2″ to 4″ over the foothills and mountains.
Snowfall accumulations of 8-18 inches are expected above 6k ft with lighter accumulations down to around 4k ft. Amounts up to 3 ft will be possible over the higher peaks. Heaviest snow is expected Friday night and Saturday resulting in travel delays over the higher northern Sierra passes.
A few thunderstorms will be possible with the front as it moves through this afternoon and evening, but a better chance of thunderstorms is expected Saturday afternoon as the upper trough moves overhead. Brief heavy rain and small hail may accompany stronger cells.
Southerly breezes of 25-35 mph will be possible in the Sacramento Valley this afternoon and evening, and again Saturday afternoon. Southwesterly gusts of 30-50 mph will be possible over exposed ridges in the mountains.
Shower chances retreat to mainly the mountains by Sunday afternoon, then a break in precipitation is expected through most of Monday.
Extended Discussion (Tuesday through Friday)
Drier weather on tap Tuesday into early Wednesday as upper level ridging moves through. NBM appears a little too fast with progression of next front compared to deterministic models. Widespread rain and mountain snow spreads from NW to SE across the CWA Wednesday into Wednesday night as baroclinic zone pushes through.
Showers possible Thursday. WPC storm total QPF Wednesday through 12z Friday showing a few tenths in the N San Joaquin Valley increasing to over half an inch in the N Sacramento Valley. Liquid storm totals in the foothills and mountains range from around half an inch to locally up to 3 inches. Snow fall amounts of 5 to 10 inches possible above 5000 feet with local amounts up to a foot or more over higher terrain.
Another Pacific frontal modeled to move through Friday into Saturday.