Brief lull in precipitation for most areas through this afternoon. Periods of rain and moderate to heavy mountain snow return tonight through early Wednesday morning with locally breezy southerly winds. Mostly dry conditions expected on Thanksgiving continuing into the weekend. Locally breezy northerly winds by mid-week. Areas of morning frost possible by mid-week. Winter Storm Warning: Until 4 AM Wednesday for elevations above 5500 feet along the Sierra/ Southern Cascades including Interstate 80 and Highway 50.
Discussion
Latest radar imagery shows generally quiet conditions prevailing across interior NorCal early this morning. HREF suggest the potential for some fog across portions of the Valley this morning (20-40% probability) given mostly clear skies and light winds.
Brief lull in precipitation is expected for most areas through this afternoon ahead of the next wave of precipitation. Models show the next round of precipitation approaching the Coastal Range later this afternoon, then gradually moving across interior NorCal tonight into early Wednesday morning.
Precipitation totals for the Valley through early Wednesday morning are roughly 0.50-1.25″, with 1-2.5″ across the foothills.
Periods of moderate to heavy mountain snow return tonight through early Wednesday morning for the northern Sierra and Southern Cascades. The National Blend of Models (NBM) suggests a 50-95% probability of snow amounts greater than 12 inches through early Wednesday morning across the southern Cascades and northern Sierra Nevada. Snow levels will initially be around 4000-5000 feet, increasing to around 5000-6500 feet on Monday, lowering to 4000-5000 feet on Tuesday. Additional snow accumulations of 1 to 3 feet are expected, with up to 4 feet along higher peaks.
As a result, the Winter Storm Warning has been extended through 4 AM Wednesday above 5500 feet. Snow-covered roads, chain controls and travel delays are likely which will result in very difficult travel at times above 5500 feet.
A few lingering mountain showers are expected through Wednesday morning. Otherwise, drier conditions return to interior NorCal by mid-week as ensembles depict an upper level ridging building in. Locally breezy northerly winds develop by mid-week. NBM indicates a 40-75% probability of wind gusts greater than 25 mph on Wednesday. NBM projects Wednesday morning lows in the mid 30s across portions of the northern and central Sacramento Valley, with the potential for some areas of frost.
Extended Discussion (Thursday through Sunday)
Thanksgiving Day is expected to be dry with light, breezy north winds as ensembles show an area of broad upper-level ridging and northwesterly flow aloft over Northern California.
Cold low temperatures may lead to localized patches of frost along the eastern half of the Valley early Thursday morning. The National Blend of Models (NBM) indicates a 30 to 60% chance of low temperatures less than 36 deg F. However, breezy north winds developing overnight into the early Thursday morning hours will keep low temperatures in the mid to upper 30s along western half of the Valley. Additionally, Thursday early morning temperatures in the mountains are forecast to be in the upper teens to mid 20s. Be sure to dress for the cooler morning weather, and ensure pets and livestock are protected from the colder temperatures.
NBM attempts to bring in slight chances of rain (15-30%) to areas south of Interstate 80. Non-impactful very light rain to sprinkles will be possible over the mountains late Thursday night into Friday morning. Little to no accumulations are expected. Otherwise conditions will be mainly dry with daytime temperatures will remain slightly below normal through Sunday as upper-level ridging amplifies over the Pacific Northwest.