Updated 5:32 p.m.
Tens of thousands of people are without power in the Sacramento region and officials are advising against mountain travel as an atmospheric river rolls over much of Northern California through Tuesday, bringing heavy rain and snow.
The National Weather Service has issued a winter storm warning through 10 p.m. Tuesday. Officials say travel through the region is already hazardous, with 3-6 feet of snow expected above 6,000 feet and 8 feet or more possible at higher mountain peaks.
"The really heavy precipitation — we're expecting near whiteout conditions and really low visibility and possibly snow rates in the 2-3 inch range [per hour] — will be coming in around between about 4 p.m. and 10 p.m. tonight," said Craig Shoemaker, a meteorologist with the National Weather Service in Sacramento. "So that's over the Sierra, I-80, Highway 50, that we're talking about."
In the valley, the weather service is forecasting 2-3 inches of rain in Sacramento, Stockton and Modesto from Sunday through Tuesday, with 5-7 inches possible in the foothills around Grass Valley and then further into South Lake Tahoe. The heaviest rain will continue through Monday evening, but some showers could stick around into Thursday as a second weather system moves in.
Periods of moderate to heavy rain and snow will pass through NorCal today. #CAwx pic.twitter.com/lZ4DtfkR2i
— NWS Sacramento (@NWSSacramento) December 13, 2021
While weaker than the storm that came through the region in October, which set records in Sacramento and around Northern California, Shoemaker said this system could cause some nuisance flooding in the region and ponding on roads. Roads may be slick, and drivers should take more time on their Monday commutes.
"The heaviest that we are expecting will be later this afternoon, early this evening. And that is really the period where we would expect maybe some standing water and some ponding," Shoemaker said. "Right during rush hour, I guess you could say for Sacramento, will be the most difficult travel due to the heavy rainfall we're expecting."
Still, the weather service said the chances of debris flows around wildfire burn scars is low, which was a major concern during October's storm.
A wind advisory is also in effect for much of the valley through 10 p.m. Monday, with wind gusts as strong as 45-50 mph possible.
"So that will also cause some travel difficulties; cars, high profile vehicles getting blown around and you certainly could see some tree branches come down and maybe even a few isolated downed trees and possibly some power outages, too," Shoemaker said.
Nearly 30,000 SMUD customers were without power as of 1 p.m. Monday, but that number was down to around 3,000 by 5:30 p.m.
This most recent storm continues what has been a wet start to the region's "water year," which runs from October to September each year. As of Sunday night, Sacramento had recorded 7.88 inches of rain since Oct. 1, more than the entire previous water year as the entire state struggles under continued drought.
Congrats, Sacramento! 🎉
— NWS Sacramento (@NWSSacramento) December 13, 2021
As of 6 PM today, Water Year 2022 (which began on Oct 1) is officially wetter than Water Year 2021. ☔ #CAwx
(Recall that the last Water Year was dismally dry🌵, so the bar was set low.) pic.twitter.com/UdZi1pI8U1
Shoemaker said in a normal year the Sacramento region should expect three to six storms the size of this current system, which provide most of the precipitation for the region. And a major difference with the current system is that much of it will fall as snow.
"And even though we've been a little bit above normal so far for rainfall for the area, the snowpack has really been lacking just because a lot of our systems that we've had have been warm in nature and really haven't delivered a lot of snow," he said. "But this is a really significant snow-producing system, so it's really going to help out with the snowpack."
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