Severe winter weather has returned to Northern California courtesy of a "Bomb Cyclone" off the coast of Northern California and Oregon. A Bomb Cyclone is a weather event where there is a pressure drop of 24 millibars or more in the span of 24 hours, and this event has had a drop of around 30 millibars in the span of 12 hours. Impacts from this weather event include heavy rain and snow, gusty winds, and colder temperatures. We've been tracking heavy rain and heavy low elevation snow across the region this afternoon and it will continue this evening. The heaviest rain and snow are expected to fall tonight through early Wednesday. Rain and snow showers will become more scattered towards Wednesday afternoon, and we'll have a chance for some thunderstorms in the valley. We've also been tracking gusty South winds developing across our region and the wind is expected to become stronger tonight. A Winter Storm Warning is currently in effect for valley areas of Shasta and Tehama Counties, and foothill and mountain areas of Trinity, Siskiyou, Shasta, Tehama, Lassen, Butte and Plumas Counties. The Winter Storm Warning is set to expire in the North end of the valley at 6am on Wednesday morning, but will linger in most mountain areas through 10pm Wednesday night. Foothill areas of Butte County, and the Western Slopes of the Sierra are set to be under the Winter Storm Warning through 7pm on Thursday evening. Snow levels will mostly dip into the 1000' to 1500' range over Northern California but we did have valley snow lower than that on Tuesday afternoon in Redding and Northern Tehama County. Up to a foot and a half of snow can be expected as low as 2000', and we could be dealing with up to 3 feet of snow down to 3000'. A High Wind Warning will be in effect in the valley through 11pm tonight and a Wind Advisory is in effect for the valley and foothills through 6am Wednesday morning. Sustained winds out of the South will be up to 30mph, and we could be seeing gusts up to 50 to 60mph during that time.
Winds will not be as strong on Wednesday and the rain and snow will become more scattered in nature by the afternoon hours. We'll have a chance for thunderstorms developing in the valley and foothills on Wednesday afternoon. Snow levels will remain down into the foothills for the next few days and we'll still have a slight chance for some Redding snow for the middle of this week. Temperatures won't be quite as cold on Wednesday but will still be well below average for this time of year. Overnight low temperatures will dip into the 30's in the valley overnight, and into the teens to 20's in the mountains. Valley areas will top out in the mid 40's to low 50's on Wednesday afternoon and mountain areas will end up in the 30's to low 40's. More showers will be possible on Thanksgiving, but they will not be as substantial. A break from the wet weather is expected in your Friday forecast, but we aren't expecting temperatures to change much in the afternoon. Overnight low temperatures will become much cooler towards the end of the week, with lows down into the 20's in the valley and into the single digits to teens in the mountains.
Another wet weather system will be on tap for your upcoming weekend. Showers will spread through the coast on Saturday morning, and will spread into the majority of our region by Saturday afternoon. Rain is expected in the valley, a mix of rain and snow can be expected in the foothills, and snow will return to all mountain areas. Rain and snow will continue through Monday. It looks like we may be in for another break from the wet weather on Tuesday of next week. Travel impacts look likely in the mountains this weekend.