Warm and dry weather continues into the weekend. Cooler weather along with a chance of precipitation returns Sunday afternoon and night.
Discussion
Clear skies cover the region early this morning as high pressure from the eastern Pacific builds in. The northerly surface pressure gradient has slackened a bit compared to 24 hours ago, but the northeast gradient has tightened. The result has been local northerly gusts in the teens mph continuing around the periphery of the northern Sacramento Valley while a few northeasterly gusts in the teens are occurring over the crest of the northern Sierra. The usual “windy” spots near the mouth of the Feather River Canyon in eastern Butte County are seeing gusts in the 20s and 30s mph.
Otherwise, temperatures are running a little cooler across much of the valley compared to 24 hours ago (especially areas that were breezy) with current readings mainly in the upper 40s to mid 50s. The foothill and mountain thermal belts are considerably milder (5-15 degrees) compared to early Thursday with current temperatures mainly in the 50s to lower 60s.
Dry and mild weather is expected today and Saturday as the mid/upper ridge moves overhead. Highs in the low to mid 80s will be common across the Central Valley while overnight lows will remain cool, in the mid 40s to lower 50s. The warmest day is expected on Saturday when highs will be around 5-10 degrees above average.
By Sunday, a potent, quick-moving short-wave is forecast to affect NorCal bringing a return of cooler and unsettled weather. Clusters in pretty good agreement with the timing of this feature later Sunday. Some lighter frontal precipitation will be possible over the northwest portion of the forecast area (mainly the Coast Range of western Shasta and Tehama Counties) on Sunday afternoon, but convective precipitation likely to increase Sunday evening along and to the north of the vort track as it swings inland. Overall, amounts are expected to be on the light side. Snow levels lower to around 5-6k ft Sunday night and snowfall accumulations of a couple of inches will be possible over the higher passes of the northern Sierra.
Other than a few lingering morning showers over the northern Sierra and southern Cascades, dry and cool weather expected Monday as the system quickly shifts east.
Extended Discussion (Tuesday through Friday)
Ensemble guidance continues to indicate a long term troughing pattern setting up over the Eastern Pacific for much of the extended period, bringing multiple chances of precipitation to interior Northern California.
A shortwave is forecast to bring the first round of showers sometime in the late Tuesday through Wednesday timeframe. The best chances for precipitation with this round would be for the Coastal Range and Southern Cascades with lighter amounts possible in the Sacramento Valley north of Highway 50. The next trough is forecast to move inland sometime late in the week, bringing a potentially more potent round of moisture to northern California.
Uncertainties still remain in precipitation timing and amounts with each system this far out, so keep an eye out for forecast updates. Gusty south to west winds are also possible with each weather system. Temperatures will remain seasonably cool through late week under this weather regime. Expect Valley temperatures in the mid 60s to low 70s with 40s to 60s in the mountains and foothills.