▶ Watch Video: Winter storm hits West as South gets a record warm Christmas

Thousands are without power on Sunday after a storm slammed the Pacific Northwest, dumping nearly 30 inches of snow in the Sierra region and leading to road closures in Northern California. The National Weather Service issued a winter storm warning for greater Lake Tahoe through 1 a.m. Tuesday and warned of “widespread whiteout conditions” and wind gusts that could top 45 mph.

As of Sunday afternoon, there were more than 20,000 without power in Washington, more than 14,000 without power in California and more than 10,000 without power in Oregon, according to PowerOutage.US.

The National Weather Service reported 3.8 inches of snow fell in Seattle, where the wind chill caused temperatures that felt like they were near zero degrees. Frigid temperatures are expected to last in the region until Thursday. 

In Northern California, 29 inches of snow fell over a 24-hour period ending Sunday morning, the UC Berkeley Central Sierra Snow Lab tweeted. The National Weather Service in Reno said snow will remain heavy Sunday night into Monday as the next storm pushes through the region.

CHP Truckee

Several mountain roads were shut down Sunday, including a 70-mile stretch of Interstate 80 through the Lake Tahoe region to the Nevada state line. The California Department fo Transportation tweeted Sunday that there was “low or zero visibility on I-80.” 

The National Weather Service in Sacramento warned on Sunday night that “mountain travel will continue to be difficult if not impossible through tomorrow.” The best time to travel will be Thursday. 

The continuing storms were welcomed in parched California, where the Sierra snowpack had been at dangerously low levels after weeks for dry weather, CBS Sacramento reported. But the state Department of Water Resources reported on Christmas Eve that the snowpack was between 114% and 137% of normal across the range with more snow expected.