A flood warning has been issued Wednesday for the Sacramento Valley after reports of localized flooding and road closures, according to the National Weather Service.
The warning, which was elevated from an earlier flood watch, will remain in effect until 8 p.m. as heavy and moderate rainfall is expected to continue through the evening, the NWS said.
“We are basically being pounded by this rain,” said NWS meteorologist Hannah Chandler-Cooley, adding that more creeks and stream are expected to rise.
Levels of a half-inch to 3 inches were dumped on the region overnight Tuesday, with 1 to 2 additional inches predicted to fall in spurts through Thursday, Chandler-Cooley said. However, it won’t be as heavy as what the valley saw Tuesday night, she said.
Areas in the far northern part of the valley are not under warning because those areas saw more snowfall overnight than rain, Chandler-Cooley said. But that snow will soon melt as precipitation turns to rain.
This storm system, which started moving across Northern California Tuesday, has brought with it gusty winds, power outages, avalanche warnings and snow in areas of the valley around Redding.
“This is a pretty strong atmospheric river,” said Emily Heller, a meteorologist at the weather service’s office in Sacramento. “It’s definitely the wettest of the systems we have seen this year.”
There will be continued rainfall Thursday before the main system moves out of the area.
Prompted by heavy rain, NWS in Reno is also warning that “roofalanches,” a sudden release of snow from roofs, could be a significant hazard Wednesday.
As rain and snow are likely to make roads slick across Northern California Wednesday, the NWS says travel could get tricky and drivers should slow down and leave extra room between vehicles.
A wind advisory is also in effect until 1 p.m., with wind gusts of up to 35 to 45 mph are expected around Sacramento, Heller said. The gusts will get weaker overnight Wednesday before another wind advisory goes into affect at 6 a.m. Thursday.
SMUD reported Wednesday morning multiple power outages in Sacramento just before 7:30, with 350 customers without power in Land Park. PG&E has also reported numerous outages through out upper Northern California.
Rain in the valley
Travel in the Sacramento Valley may be moderately impacted all day, with roadway flooding and longer commutes, the NWS said.
Up to 4 inches of rain have been predicted to fall in the Sacramento Valley by Thursday, with up to seven inches in the foothills, and high wind levels may pose additional hazards.
“Given recent periods of wet weather, the region will be more conducive to flooding issues,” the NWS said. “Ponding on roads will be likely across the area.”
Caltrans reported multiple incidents of flooding on the state highways and local streets already Wednesday morning and are encouraging drivers to be careful and check road conditions and closers before traveling.
Parts of the Sacramento and Cosumnes rivers may be reaching levels requiring monitoring over the next few days, according to the NWS.
The NWS is reporting downtown Sacramento received more than half an inch of rain overnight and about 1 inch near Sacramento State in the last six hours, with areas to the north seeing nearly double that – Redding recieving 1.95 inches in the last 24 hours ending at 4:30 a.m. is the highest, with Mount Shasta City and Konocti both seeing more than 1.5 inches.
Redding is expected to see 3 to 4 inches of rain from this storm system, while Sacramento may see 1 to 2 inches, according to the NWS
Grass Valley has the highest rainfall prediction with as much as 7½ inches, according to the NWS.
Snow in the Sierra
More hazards are expected in the Sierra as the region is still recovering from its last bout of heavy snowfall.
NWS Reno has issued a high avalanche warning through Thursday night “due to heavy dense snow fall with extreme southwest winds and rain falling on snow at lower elevations.”
There have been some reports of at least 2 feet of snow falling overnight Tuesday already in the Sierra Nevada, with up to 2 feet expected to fall overnight Wednesday, Heller said. Some areas could see as much as three feet.
Snow levels were around 1,500 to 2,000 feet Wednesday morning, with snow reports coming out of elevations as low as Redding and Cottonwood, but were expected to rapidly increase throughout the day, Heller said.
Warmer air being brought in by this current storm system will raise snow levels to around 5,000 or 6,000 feet and continue to increase through Thursday to maybe 7,000 feet, Heller said. But snow levels will then drop again Thursday.
The NWS said travel over the mountains on Wednesday would be highly dangerous.
The NWS issued a winter storm watch starting Tuesday for the Sierra as well as parts of the Klamath Mountains and the North Coast, warning of visibility reductions, chain controls and travel delays due to heavy snowfall.
By Thursday, the Sierra may receive more than 8 feet of snow at higher elevations, according to the NWS.
Interstate 80 at Donner Pass is predicted to receive 3 to 4 feet of snow, while Interstate 5 north of Redding may see 2 to 2½ feet. Highway 50 at Echo Pass may see 2 to 3 feet, the NWS said.
Lassen Peak will see the most snow, with anywhere between 6.6 and 8.3 feet of snow predicted by the NWS.
Peak wind gusts in the South Lake Tahoe area may reach 60 mph, while ridgetop gusts could reach 150 mph, according to the NWS.
“Travel is expected to be difficult during this time and is discouraged,” the NWS said in its storm watch.
By Thursday afternoon, travel may still be hazardous as snow levels are expected to drop down to 3,000 feet by nightfall, the NWS said.
Anyone traveling into higher elevations in the next few days should expect to use chains and be prepared for road closures.
Friday and beyond
The main storm system will leave the area Thursday and dissipate into another storm system over the weekend, Heller said. Although it will bring some rainfall to the valley, this next storm will likely have more of an impact on areas in the higher elevations.
The Sierra may receive a quarter-inch to a half-inch of snow Friday and snow levels may remain as low as 2,500 feet, according to the NWS.