Warm weather continues today and Friday. Cooler and breezy this weekend into next week with a chance of showers Saturday. Gusty winds, dry fuels, and low humidity will lead to easier fire starts and the potential for rapid spread of new or existing fires.
Discussion
Clear skies cover interior NorCal as ridging lies overhead and the cutoff low remains well offshore from SoCal. Offshore flow continues to predominate and local north to east wind gusts of 15-30 mph are present again early this morning over the foothills and northern Sierra. Another day of unseasonably mild temperatures is expected with highs forecast to reach the mid 80s to mid 90s across the Central Valley.
A series of short-waves passing to the north will further weaken the ridge on Friday resulting in modest cooling across the area, but it will still be unseasonably mild.
Highs will lower from around 10-15 degrees above average today to only about 5-10 degrees above normal on Friday.
Much bigger changes are expected this weekend as ensembles dig a strong trough into the West bringing cooler and breezier conditions along with a chance of showers. NorCal will be on the backside of this quick-moving system with showers mainly expected along the east side of the valley up into the northern Sierra Saturday morning with showers lingering in the Sierra into Saturday evening.
QPF is expected to be generally light with only a few hundredths of an inch in the valley and up to half an inch or so across the higher elevations of the northern Sierra.
A few inches of snow accumulation will be possible along the Sierra crest as snow levels lower, but impacts to travel will likely be limited due to the recent warm temperatures.
North to east surface pressure gradients increase again behind the system on Sunday, and the result will be breezy to windy conditions with widespread gusts of 25-35 mph possible in the valley and locally across the northern Sierra.
Extended Discussion (Monday through Thursday)
Ensembles show an eastern Pacific ridge developing early next week with NorCal under dry northwesterly flow. Weak disturbance moving to the southeast in the northwest flow may bring a few mountain showers Wednesday along with cooler temperatures. Then, weak ridging develops late next week.
Forecast highs in the Valley will be in the low to mid 70s through the period.