Warm and dry conditions continue into next week. Gusty north winds Thursday and Friday will bring critical fire weather concerns for the Central Valley and foothills.
Discussion
A few high clouds are moving south across NorCal early this morning, otherwise skies remain clear. Surface pressure gradients are beginning to reverse toward offshore, but enough onshore gradient persists from the coast into the southern Sacramento Valley to lower current temperatures into the mid to upper 50s. Elsewhere, current temperatures are milder across the northern half of the Sacramento Valley with readings in the 60s to mid 70s.
The warmup will continue today as short-wave ridging moves overhead and northerly surface flow predominates. Most areas will see around 5-10 degrees of warming compared to Tuesday with highs topping out in the mid to upper 90s across the Central Valley.
Main weather concern this week remains the moderately strong north wind event on Thursday and Friday and the associated fire weather impacts resulting from it. North to east surface pressure gradients tighten Thursday, peaking Thursday night and early Friday at around 14-16 mbs (MFR to SAC) and around 8-10 mbs (RNO- SAC). Widespread gusts of 30-45 mph will be likely through the Central Valley, with local gusts over 50 mph possible along the western edge of the valley and windier spots in the northeast foothills.
Combined with very low RH (single digit minimums with poor overnight recovery) and drying fuels, critical fire weather conditions will be likely and a fire weather watch has been posted.
Around 5-10 degrees of cooling can be expected Thursday and Friday before temperatures begin to rebound Saturday. Northerly flow will continue Saturday, but it won’t be as strong as gradients relax.
Extended Discussion (Sunday through Wednesday)
Ensembles show flat ridging as the main feature for interior NorCal in the extended. As such, dry weather and above normal temperatures will prevail. Widespread mid to upper 90s are expected early next week, with some locations coming close to the 100 degree mark by Monday. Heat risk guidance suggests moderate heat risk across the Valley through the extended. This will impact groups that are sensitive to the heat.