Cold AM temperatures and dry weather again today. Winter storm moves in late Wednesday night through Friday with widespread rain, mountain snow, gusty southerly winds, and isolated thunderstorms. Major mountain travel impacts expected Thursday into early Friday.
Discussion
Mostly clear skies this early morning, with Valley temperatures still mostly hovering around the mid 30s to mid 40s. With breezy to gusty northerly winds in the northern Sacramento Valley, it’s unlikely locations like Redding or Red Bluff will reach freezing this morning, though at locations further south in the Valley there’s still plenty of time to cool down to the lower 30s. Otherwise, dry and cool weather continues today.
Wednesday sees the return of wetter weather, as an atmospheric river moves into the area. Precipitation begins in earnest Wednesday night, with the main question remaining being how quickly the cold air currently present is pushed out of the area. Currently, snow levels look to start fairly low in Shasta County (around 1500 to 2000 feet), rising throughout the night and into Thursday (up to 4500 feet by Thursday mid-morning).
Snow levels in the Sierra will start a little higher (around 3500 to 4000 feet) and rise to around 4500 to 5500 by Thursday morning. NBM probabilities of 6 inches or more along I-5 in Shasta County are currently running around 30 to 55%, with lower totals possible along lower parts of I-5 as well. In the Sierra, there is a 40 to 70% chance of a foot or more of snow between 5000 and 6000 feet, with an 80 to 100% chance of 2 feet or more above 6000 feet.
We’re also expecting strong winds with this system, generally around 30 to 45 mph gusts in the Valley on Thursday, and 60 to 70 mph in the mountains, so travel conditions on Thursday will be made even more difficult. With all of this in mind, a Winter Storm Watch remains in effect for Shasta County and the Coastal Range above 2000 feet, and for the Sierra above 4500 feet, from Wednesday evening through early Friday morning.
In addition to snow and wind, lower elevations will also see a decent amount of rain between Wednesday night and Friday morning. Valley locations have a 50 to 80% chance of seeing 1 inch or more over 48 hours, and foothills and Shasta County locations have around a 50 to 85% chance of 2 inches or more in the same time period.
People should use extra caution with this upcoming rain. With the last storm saturating soils, minor urban and small stream flooding impacts are more likely. Use caution while driving, and be aware of current conditions if you live in a low-lying area or near a waterway, and be sure to follow any instructions from local officials!
Extended Discussion (Saturday through Tuesday)
Saturday looks to be mostly a transition day after the mid week storm to another weather system which will push into the area Saturday night through Sunday. This system looks much weaker than the upcoming mid-week storm, and appears to be more progressive as well. Minimal impacts are expected from this weekend storm, with minimal dustings of snow, light rain, and only light to breezy winds. Monday, as any lingering precipitation tapers off, it appears we can expect a return to drier and slightly warmer weather.