Cold and dry weather continues today. Precipitation chances return tonight and Tuesday, and the active weather pattern will persist through the weekend with periods of heavy mountain snow and mountain travel impacts. Very cold lows expected Thursday morning.
Discussion
Current GOES-West visible satellite imagery shows some passing mid to high levels clouds over interior northern California on this Monday afternoon. Dry conditions are being observed, with cool temperatures generally in the 50s in the Valley, 40s to 50s in the foothills, and 30s to 40s in the mountains, valid at 130 PM PST.
Mainly dry conditions are expected to prevail today, before a quick round of precipitation moves in later tonight into Tuesday, in the form of scattered light Valley and foothill showers and a few inches of snow over the mountains.
Then, the next storm system moves in late Tuesday, bringing in impactful snow to the mountains, and light rain showers to the Valley and foothills through Wednesday. Minor snow accumulations will also be possible in the upper foothills.
A Winter Storm Warning has been issued for the Western Plumas/Lassen area and West Slope Northern Sierra from 10 PM PST Tuesday through 10 PM PST Wednesday for snow accumulations of up to 10 to 20 inches above 3500 feet (heaviest midday Wednesday) and wind gusts up to 50 mph especially over the Sierra Crest.
Travel delays from chain controls, reduced visibility and snow covered roads are all likely, with possible road closures as well.
For the Coastal Range, Shasta County Mountains, and Burney Basin, a Winter Weather Advisory has been issued from 10 PM PST Tuesday through 4 PM PST Wednesday for snow accumulations of 4 to 8 inches above 2500 feet (heaviest Tuesday night into Wednesday morning) and wind gusts up to 45 mph.
Snowfall looks to taper off later on Wednesday with mainly dry conditions returning to the region and clearing skies.
The clearing skies Wednesday night combined with cold air will allow for very cold low temperatures on Thursday morning. There is potential for Hard Freeze on Thursday morning, as the National Blend of Models (NBM) suggests a 55 to 95 percent probability of temperatures less than 28 degrees in the Valley, mainly from the Delta and Sacramento northward. Lows in the 20s to low 30s are forecast for the Valley and foothills, with single digit to 20 degree lows for the mountains. People should plan ahead and take the necessary precautions to stay safe in the cold weather!
Extended Discussion (Friday through Monday)
Upper riding moves into NorCal Friday with mainly dry weather except some overrunning light precip possible over the Shasta county mountains. Ridge axis shifts east through early Saturday ahead of approaching Pacific storm. Models suggest widespread precip likely Saturday with significant snow possible in the mountains. Snow levels early Saturday look to around 4,000 feet, rising to 5000 feet Saturday afternoon/night.
Drier weather returns Sunday into Monday under strong upper level ridging.