Unseasonably warm through Friday with record or near record high temperatures. Gusty winds with elevated fire weather concerns return over the weekend. Much cooler with shower chances early next week.
Discussion
Satellite imagery shows a few high clouds approaching the NorCal coast, otherwise skies remain clear across the region. The northerly surface pressure gradient has slackened considerably since Wednesday morning, however the easterly gradient is tighter (around 8 mbs RNO to SAC) and the usual windy spots in the northern Sierra are seeing gusts in the 20-30 mph range while Jarbo Gap is gusting to around 40 mph.
Current temperatures are very mild with many locales seeing readings that are running 5-10 degrees milder compared to this time early Wednesday. Temperatures are presently in the 50s to lower 60s across much of the Central Valley. The main short-term weather concerns continue to focus on the unseasonably warm temperatures today and Friday with record (or near record) highs possible, and then the strong northerly breezes over the weekend as the warmth abates.
The strong ridge peaks over the area today, then begins to shift east on Friday as the next upstream trough moves into the PacNW.
Current records for today.
Redding/Redding Airport…..94 in 1924
Red Bluff……………….97 in 1989
Downtown Sacramento………91 in 1989
Sacramento Exec………….90 in 1989
Stockton………………..91 in 1989
Modesto…………………94 in 1989
Current records for Friday.
Redding/Redding Airport…..93 in 1989
Red Bluff……………….96 in 1989
Downtown Sacramento………91 in 1989
Sacramento Exec………….90 in 1989
Stockton………………..90 in 1989 Modesto…………………92 in 1989
It’s still looking like an extended period of breezy to windy conditions will develop over the weekend as NorCal will be on the backside of the trough as it digs into the western US. Still some uncertainty in the details, but ensembles continue to point toward potential for a solid wind advisory level event (gusts 40-50 mph) for the Sacramento Valley and surrounding terrain.
Elevated fire weather conditions, local power outages and difficult driving conditions will be possible.
In addition to the wind, temperatures will be dramatically cooler over the weekend (around 15-20 degrees cooler compared to today) and will range from the upper 60s to mid 70s across the Central Valley by Sunday.
Extended Discussion (Monday through Thursday)
A generally cool and unsettled week is expected next week. On Monday model ensembles are in good agreement that a cold upper level trough will drop down into the area from western Canada. There has been some increased confidence in the potential for precipitation and for higher amounts.
Ensemble members are showing better confidence for some rain and mountain snow, though exact amounts remain uncertain. The trajectory of this system favors the northern Sierra, where up to three quarters of an inch of liquid equivalent are currently projected.
Due to the cold nature of this system, this would be mainly in the form of snow over the mountains and upper foothills, with storm totals Monday and Tuesday of around 5 to 10 inches possible above 4,000 feet.
If these amounts hold up, this would mean travel impacts Monday and Monday night for mountain highways, especially for the Sierra passes. If you must travel during this period it is a good idea to plan ahead for winter driving conditions, including having chains and winter clothing in your vehicle.
Cold air aloft will bring some unstable conditions, and this could lead to a few isolated thunderstorms Monday afternoon. Any details on this potential will have to wait until we get closer to the period.
Breezy north to northwesterly winds are expected Monday and Tuesday, but won’t be as strong and increased RH levels should diminish fire weather concerns.
An unsettled pattern continues for the rest of the week with below normal high temperatures. Lows could drop into the upper 30s Tuesday and Wednesday morning. Another reinforcing shortwave from western Canada is possible Wednesday night into Thursday, with the possibility for some precipitation, but confidence is low at this time.