A substantial winter storm is making it's way into northern California tonight and will continue to track across our region through at least early Friday. Major impacts can be expected from this system, and a Winter Storm Warning is going into effect in many areas of Northern California this afternoon and tonight. The Warning will be in effect as early as 4pm in parts of the Northern Mountains, by around 6pm for portions of Siskiyou and Shasta Counties, and at midnight in portions of the Sierra and Cascades. The Warning will last through 4pm Thursday for portions of the Northern Mountains, but will persist in other areas through 6am Friday morning. The Winter Storm Warning will be in effect for areas down to around 2000', but snow levels will be lower than that in some areas. We'll even have a chance for some snow showers hitting the valley floor in Redding on Thursday and a chance for more Redding snow showers on Friday morning. Snow totals are projected to end up in the 1' to 2' range in most areas, with some localized snow totals up to around 3' at higher peaks. A Wind Advisory will also go into effect at 10pm tonight for portions of Lassen and Plumas County for gusts up to 70mph out of the South. A Wind Advisory will go into effect in the valley at midnight tonight, and will last through 10am Thursday for gusts out of the South in the 40 to 50mph range.
Heavy rain and snow showers are moving into the Northern Mountains this afternoon and will then slowly spread toward the valley and Sierra by around midnight or shortly after. The Northern Mountains will see the heaviest rain and snow from 6pm tonight through midnight. Valley areas are expecting the heaviest rain between midnight and 8am. The Sierra will have then have the heaviest snow showers between 4am and noon tomorrow before showers become somewhat more scattered in nature. There will also be a chance for valley thunderstorms on Thursday afternoon and evening. Valley areas can expect between a half an inch to an inch of rain from this system. Much bigger impacts are expected from heavy snow in the mountains. Amounts of 2 inches or more an hour will be possible in the Sierra early in the day on Thursday and that could make mountain travel difficult to impossible there during that time. Chain requirements and road closures can be expected as this storm system continues into early Friday. As stated above, mountain areas down to 2000' can expect 1 to 2 feet of snow, with some higher peaks seeing up to 3 feet of snow during this storm.
Scattered showers are expected to persist into early Friday, but they are not expected to be as heavy as what we'll experience on Thursday. We'll see somewhat of a lull in the chance for showers late in the day on Friday and then another wet system is projected to clip the Coastal Range and Northern Mountains late Friday night into mid day Saturday. Valley and Sierra locations are not expected to see much in the way of wet weather on Saturday. We'll have a break from the active weather on Sunday, but models are hinting at another modest wet system moving through mostly mountain areas of northern California on Monday afternoon through early Tuesday.