Cool and unsettled weather continues early this week with scattered showers and thunderstorms, and mountain snow. Dry and warmer weather returns late this week.
Discussion
Clear to partly cloudy skies cover most of the Central Valley early this morning while a few light showers linger across the northern Sierra Nevada. Winds are much lighter across most of the area compared to 24 hours ago, though a few locales are still reporting gusts in the teens and 20s mph. Current temperatures are chilly ranging from the 20s in the mountains to the 40s across the Central Valley (around 5-15 degrees cooler compared to 24 hours ago).
Cool and unsettled weather with scattered showers/thunderstorms and occasional high elevation snowfall will continue across interior NorCal today and Tuesday as the upper trough moves overhead and closes off. Depending on the amount of deep convection that develops today, travel impacts may redevelop across the higher Sierra passes where several inches of snowfall accumulation will be possible.
Forecast soundings indicate the primary threat from stronger storms this afternoon will be copious amounts of small hail given the cold mid and upper-level temperatures (500 mb temps around -30C). Stronger shear will be shifting south.
The trough is forecast to shift east on Wednesday allowing most of the region to warm about 10 degrees from Tuesday as short-wave ridging moves, but highs will still be around 5 degrees below average. The Sierra south of Tahoe will still see a chance of wrap-around showers on the backside of the departing trough. A few showers will be possible across far northern California on Thursday as another trough brushes by to the north, but most of the forecast area will remain dry with not much change in temperatures compared to Wednesday.
Extended Discussion (Friday through Monday)
Clusters are in good agreement that upper level high pressure will begin to impact interior NorCal beginning Friday, continuing throughout the weekend. Biggest uncertainty looks to be the amplitude of this ridge.
Warming trend is expected Friday into the weekend with the hottest day potentially Sunday. In the Valley, moderate heat risk will be possible for certain locations in the afternoons from Saturday into Monday.