January 21, 2017 – Scattered showers expected today with possible isolated afternoon thunderstorms. Next strong Pacific storm brings widespread precipitation to Interior Northern California tonight into Sunday turning showery later Sunday through early Tuesday. System expected to produce around 1 to 2 inches of rain in the Central Valley with heavy snow in the mountains above 3000 feet. Hazardous mountain travel likely with chain controls, delays, accidents, and white-out conditions at times. Strong winds will develop tonight and persist through Sunday morning with possible downed trees and power outages. Isolated thunderstorms which may produce small hail will be possible today through Monday, especially in the afternoon. Localized flooding remains a concern, especially near area creeks, streams, and rivers. Decreasing showers expected later Monday into early Tuesday, then dry weather forecast through the remainder of the week. Winter Storm Warning until 4 am Monday, Wind Advisory from 10 pm this evening to 10 am Sunday.
Cold and unstable atmosphere will continue scattered showers across the region today. A clap of thunder or two may accompany some of the heavier showers. Snow levels will remain around 3-4K ft. Breezy southerly winds will continue.
The next storm system will move through NorCal tonight into Sunday with valley rainfall of 1 to 2 inches and mountain snow of 2 to 4 feet (locally higher amounts) and snow levels 3-4K feet.
Another round of strong gusty winds are anticipated with this system. South to southeast winds will increase late this evening beneath 55-65 kt 925 mb jet max. This will translate to 25-35 mph winds with gusts to 55 mph over the Sacramento/northern San Joaquin Valley (Redding to Modesto) into Sunday morning. Winds of this magnitude will continue to pose a threat for tree damage and power outages.
Front and deeper moisture are shunted south later Sunday for diminishing precip and lighter winds. Some partial clearing across the northern half of the Sacramento Valley Sunday afternoon may pose a threat for some stronger thunderstorms. Showers continue Monday.
Stacked surface/upper low progged to continue filling as it drops southeastward Monday night into early Tuesday and will provide the final chance for showers for NorCal through this period of wet weather.
Extended discussion (Wednesday through Saturday)
Extended period of dry weather expected across the region during the extended forecast period as models continue to show strong ridging along the West Coast. Daytime highs start out slightly below normal then climb to a little above normal by the end of the week. Cool nights with fair skies allowing overnight lows to drop to a little below normal.