Winter storm will continue deluge, making Sierra travel especially difficult

A winter storm that has been moving across California since Friday is showing no signs of slowing down, especially in the mountains, with thunderstorms and even the threat of tornados late Saturday, according to the National Weather Service.

More rain and snow is expected Sunday, making driving conditions in the Sierra Nevada hazardous and prompting the National Weather Service to issue flash flood watches in several fire-affected areas.

For about an hour around noon, Caltrans closed portions of Interstate 80 due to vehicle spinouts and collisions. The major roadway is now open, though chain restrictions are in effect. The transportation agency also reported an overturned vehicle on Highway 50 by Sierra at Tahoe, though it said traffic was moving in both directions.

Just after 4 p.m., the weather service issued a tornado warning for Butte, Colusa and Glenn counties, which expired without incident.

Heavy snowfall in the mountains will continue through Tuesday, dumping 5 to 10 feet of snow in pass areas along Interstate 80 and Highway 50, said Idamis Del Valle, NWS meteorologist. The highest peaks could hit levels of up to 13 feet.

On Monday, snow levels could drop between 1,000 and 2,000 feet in elevation, the weather service said. For now, snow levels will remain above 3,500 feet through Sunday night, she said.

NWS Reno issued a backcountry avalanche watch in the greater Lake Tahoe area, between Yuba Pass and Ebbetts Pass, through 7 a.m. Tuesday.

The NWS in Sacramento tweeted out Friday that traveling into the Sierra is highly discouraged.

Caltrans also advised against traveling into higher elevations, but said those planning a trip into the mountains should allow for extra travel time and be prepared to get out those chains.

Updated information on chain control areas can be found at quickmap.dot.ca.gov.

The storms so far have dropped .87 inches in Sacramento in the 24 hours ending at 4 p.m., with areas north receiving twice that amount or more in the period – Alder Springs receiving 1.77 inches, while Redding, Red Bluff, Blue Canyon and Paradise are seeing more than 2.4 inches and Konocti on Clear Lake recording 2.97 inches – the weather service reported.

Showers are expected to continue in the Sacramento Valley through Saturday and has the potential for thunderstorms later in the day, Del Valle said, as another band of widespread precipitation will reach the area after 6 p.m.

“There could be some brief lulls, but overall the pattern will remain pretty active through Monday in the valley, decreasing shower activity on Tuesday,” Del Valle said.

The valley is expected to get 1 to 3 inches of rain through Tuesday, while the foothills are expecting 3 to 7½ inches of rain, Del Valle said.

A flash-flood watch has also been issued through Monday for burn scar from multiple fires in Northern California.

Residents in the areas of the Camp, Mendocino Complex, Carr, Hirz and Delta fires burned should be on the look out and prepared to evacuate if necessary, according to a NWS tweet.

Flooding could increase debris flow consisting of rock, mud, vegetation and loose materials, the NWS said.

“Especially if thunderstorms move into the area,” Del Valle said.

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