Cooler weather into next week. A weather system moves through today bringing showers to the region and some snow to the highest elevations. Lower shower chances at the end of the week.

 Early season rain may lead to slick roads.


Satellite imagery shows approaching Pacific frontal system to our north over Oregon. Mid and high clouds are increasing across the northern mountains and northern Sacramento Valley, and a few showers will be possible toward morning. The remainder of the region remains under clear skies.

The weak offshore flow of the past few days is reversing and southerly flow has returned to region ahead of the front with local gusts of 15-25 mph. Current temperatures are mainly in the 40s and 50s in the mountains, and in the mid 50s to mid 60s across the Central Valley.

Precipitation totals for today

The cold front will push south through NorCal later today and tonight bringing a quick shot of precipitation to the region, mainly this afternoon and evening. There’s a decent moisture plume (TPW of 1″-1.25″) ahead of the front, and forecast moisture transport qualifies as a weak AR.

Strongest forcing will remain over NE California with the upper trough, with forcing and IVT dropping off considerably further south, especially over the southern half of the forecast area.

Sierra snow forecast for Wednesday

Still looks like most mountain areas will see QPF in the 0.25″ to 0.50″ range while the valley will mostly be under 0.05″. The high Sierra (above 8k ft) will see some accumulating snow of 2-4 inches. Local amounts of 6-9 inches will be possible across the highest peaks of the southern Cascades and northern Sierra. The higher mountains passes (80 and 50) are likely to see less than an inch of snowfall accumulation, and with recent mild temperatures snow may not stick much to road surfaces.

High temperature forecast

Ensembles continue to taper precipitation prospects for Friday night and early Saturday with perhaps some light showers possible, otherwise dry weather is expected Thursday into the weekend.

Minor wind event forecast for Saturday and Sunday

Much cooler temperatures are forecast the remainder of the week with highs down around 10-15 degrees compared to earlier this week. Overnight lows will become chilly with coldest portions of the valley expected to dip into the upper 30s while teens and 20s will be possible in the colder mountain locales.

Extended Discussion (Sunday through Wednesday)

Drier weather expected Sunday into Tuesday as high amplitude upper ridging builds into the CWA. Areas of gusty north to east wind possible Sunday into early Monday.

Models differ with how progressive ridge and next upstream Pacific frontal system are. NBM leans towards more progressive GFS with increasing POPs over the area Wednesday. Below normal high temperatures expected through the extended forecast period.