Colder unsettled weather into Saturday with significant snow in the foothills and mountains, and possibly in northern and western portions of the Central Valley. Windy at times into Friday. Additional rain and foothill/mountain snow Sunday into early next week.
Discussion
Deep trough continues to develop over western North America. Showers have been pretty sparse in the Central Valley overnight under northwesterly flow aloft and in-between stronger short- waves, but upslope flow has allowed light to moderate snow to persist across the northern Sierra and southern Cascade Range where widespread travel impacts continue with numerous chain controls in effect.
It is downright cold with current temperatures in the teens over the mountains, 20s in the foothills and upper 20s to upper 30s across the Central Valley. Deep closed low off the PacNW coast forecast to drop southward off the coast later today and Friday.
This system will bring significant heavy snow in the mountains and foothills, especially later today, tonight, and Friday. Potential for accumulating snow in the Northern Sacramento Valley and western foothills of the Sacramento and Northern San Joaquin Valleys around 1000 feet tonight into Friday morning.
Wind will increase later today over the Central Valley as system approaches with southerly gusts of 40-50 mph possible, mainly tonight into Friday. Thunderstorms possible again this afternoon over the Central Valley and foothills.
Accumulating hail and even thundersnow could be possible with stronger cells. Shear profiles are favorable for rotating storms with possible funnel clouds or brief touchdowns.
Precipitation decreases from the north on Friday night into Saturday as offshore upper low continues to drop south off the CA coast. Wrap around showers will continue over southern portions of the CWA and Sierra Nevada Saturday, mainly from I-80 southward. Snow will continue to be possible in upper portions of the foothills Saturday, but QPF will be lighter.
Next system moves in from the north on Sunday with heavy snow possible in the northern Sierra again by Sunday afternoon.
Extended Discussion (Monday through Thursday)
Clusters and ensembles are bringing a wetter system through the area late Monday into Tuesday. The system looks cold but not as cold as the current one. The storm path while still dropping down from the north is a little further west so should pick up more moisture and help rise snow levels some. That said snow down to around 2000 feet looks good at this time but could go a little lower.
The low will stay over the region at least into Wednesday providing unsettled weather for the first half of next week. Heavy snow for the mountains is likely.
Cold unsettled pattern will also bring a good chance for some thunderstorms. By Thursday a ridge will build over the region to keep the area dry with breezy north winds for the valley.