Dry and not as hot through mid-week. Isolated Sierra Crest thunderstorms possible Thursday, otherwise dry. High pressure strengthens bringing a return of very hot weather by the weekend into next week.
Discussion
Cutoff low remains nearly stationary off the coast to the west of the Bay Area. Satellite imagery shows a large area of mid/upper clouds persisting over much of northeast California to the northeast of the low. Forecast sounding indicate a thin layer of elevated moisture, and cloud bases over Shasta County are likely around 15k ft or higher. Just enough moisture and elevated instability exists further north to realize a few thunderstorms along the OR/CA border. Onshore flow continues to spread cooling inland and most areas are running several degrees cooler compared to 24 hours ago. Current temperatures range from the 50s and 60s in the mountains to the 60s and 70s across most of the Central Valley. Areas near the Delta are in the mid to upper 50s.
The low is forecast to edge a bit closer to the coast today and Wednesday continuing to moderate temperatures and RH inland across interior NorCal as onshore flow continues. Thunderstorm chances will likely remain outside the forecast area where a little more elevated moisture and instability will be present.
Ensembles trending towards the upper low drifting a bit to the southeast on Thursday allowing some elevated moisture to work its way back into NorCal for a better chance of thunderstorms over the mountains. Storms will likely be high based and rainfall should be limited.
Confidence is high that the next warming trend begins late in the week as strong ridging builds and helps to suppress deep convection.
Extended discussion (Saturday through Tuesday)
Near 600 DM upper high sets up over the Intermountain West through the extended forecast period resulting in dry weather with very hot temperatures. Widespread triple digit heat expected in the Central Valley with overnight lows in the mid 60s to low 80s. Sunday looks to be the hottest day with record heat likely.