Shower and thunderstorm chances will retreat to the northern Sierra the rest of the week. Temperatures will return to above average by the weekend.
Discussion
Clear to partly cloudy skies cover the region as we’re between the closed low moving through SoCal and a series of short-waves passing to the north through the PacNW. Onshore flow and a relatively deep marine layer has resulted in a narrow band of marine stratus moving inland through the Carquinez Strait into the Sacramento area.
Current temperatures are similar to 24 hours ago and range from the 30s and 40s in the mountains, to the mid 50s and 60s across the Central Valley.
Late day thunderstorm chances will likely retreat to the northern Sierra and southern Cascades today and Thursday as drier air gradually works in on west-southwest flow. Enough moisture and instability may linger today to pop an isolated storm over the Coast Range, but that area is likely to see much less activity over the next few days.
By Friday and Saturday, only areas south of Tahoe in the Sierra will see a slight chance for thunderstorms.
Temperatures will be close to average today and Thursday, but will warm to around 5-10 degrees above normal by Saturday as high pressure strengthens and onshore flow slackens. Highs will be in the mid to upper 90s across the northern half of the Sacramento Valley, and areas of moderate heat risk will return.
Extended Discussion (Sunday through Wednesday)
In the extended period, weak upper ridging lingers over NorCal as closed upper low slowly progresses through SoCal. Sunday appears to be the warmest day with high temperatures upwards of 10+ plus degrees above normal. NBM max temperatures in the Northern Sac Valley forecast to be near the century mark.
Highs slowly trend down to near or slightly below normal values by midweek.
Threat of afternoon showers/thunderstorms over the Sierra Nevada Sunday, expands to include all of the interior mountains and possibly northern and eastern portions of the Sacramento Valley early next week.