February 14, 2018 – A slight chance of light showers over the mountains thru tonight and again early next week. Cooler temperatures today, then milder heading into the weekend. Turning below normal early next week, with a possible widespread freeze.
Discussion
Clear skies and chilly temperatures across most of interior NorCal early this morning. Current temperatures are running around 5-15 degrees cooler across much of the region compared to 24 hours ago and range from the mid to upper teens in the mountain valleys to the 30s elsewhere, except 40s across the foothill and mountain thermal belts. The exception is the northern San Joaquin Valley and Motherlode where mid-level clouds to the north of the low off the SoCal coast are resulting in a little milder temperatures there.
Satellite imagery shows the next upstream system presently off the PacNW coast. High clouds out ahead of it are already streaming into far northern California. The body of the trough will dig southeast to the east giving NorCal a glancing blow through tonight. Cooler temperatures are expected today along with a chance of snow showers across the mountains into early Thursday. This system is cool, fairly dry and fast moving, so light QPF is forecast.
Thursday, dry and slightly milder temperatures return as upper level ridging rebuilds. Breezy northerly winds develop gusting to around 30 mph in the Valley. Gradually milder weather continues into the weekend with lighter north winds Friday and Saturday.
Extended discussion (Sunday through Wednesday)
Extended forecast period consists of high amplitude upper ridging in the EPAC with deep troughing along the West Coast. Troughing forecast to dig Sunday into Monday ushering significantly colder air into Interior NorCal. Unsettled weather expected with showers possible over the foothills and mountains and snow levels lowering into the foothills Monday. Highs in the lower 60s in the Central Valley Sunday drop into the 50s Monday and Tuesday. Cold overnight low temperatures forecast early next week with 20s to low 30s forecast in the Central Valley Tuesday morning.