Cooler temperatures and breezy conditions expected this weekend. Scattered light precipitation in the mountains today. Dry north to east winds expected for Sunday. Fire Weather Watch from Sunday afternoon through Sunday evening for Carquinez Strait and Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below 1000 Ft-Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft-Northern San Joaquin Valley in San Joaquin and Stanislaus Counties Below 1000 ft-Southern Sacramento Valley in Yolo-Sacramento Far Western Placer, southern Sutter and Solano County Below 1000 Ft.
Discussion
Interior NorCal radars are spinning in precipitation mode this early Saturday morning as a band of elevated, light precipitation passes through the region. Surface observations have been rather underwhelming as most of these radar returns are virga (precipitation that evaporates before reaching the ground). That said, Redding and Marysville airports both reported a Trace in the last few hours.
As the morning progresses, expect light precipitation chances to continue in the mountains. Valley communities will largely miss out on any measurable rain chances. Even in the mountains, total precip amounts will generally be upwards of 0.1 to 0.2 inches.
Overall this is a marginal downward trend in QPF over the past 24 hours. (Official forecast follows the Weather Prediction Center QPF guidance.) Winter enthusiasts may be able to find a few inches of wet snow above 8000 ft by late Saturday afternoon / night as colder air filters south.
Overall: little/no precipitation-related impacts anticipated. Winds, on the other hand, will be a bit more impactful this weekend.
Breezy west/northwest winds today in the Valley will gust to around 15 to 25 mph, and west/upslope mountain gusts upward to 40 to 60 mph (strongest at peaks/ridgetops). As the upper-level trough passes east, winds will become offshore (north/east) for the second half of the weekend, which will promote a downward trend in relative humidity values.
Gusts for Sunday will increase in the Valley to around 20 to 30 mph, locally around 35 mph west of the I-5. Saturday’s upslope winds in the mountains will reverse on Sunday/early Monday becoming downslope.
The gusty winds and lowering humidity values prompted a Fire Weather Watch for Sunday afternoon and evening. Will continue to closely monitor humidity and wind forecasts over the next few forecast cycles and evaluate this watch.
For Monday, ridging returns to northern California with decreasing winds and a gradual warming trend for temperatures. Ensembles suggest shortwave trough approaching northern California around Tuesday. While very light precipitation chances may make it to parts of Shasta / and the southern Cascades, current thinking is that the best locations to receive precipitation will be to our north and west through Tuesday.
Extended Discussion (Wednesday through Saturday)
Models trending weaker with cool midweek wave over our CWA, and NBM pops look overdone. Dry weather expected Thursday as high pressure builds inland and includes some gusty northerly wind. Model differences increase towards the end of the week with NBM/EC showing wetter short wave trough spreading some precip into the CWA Friday into Saturday.