San Francisco has first-ever Tornado Warning as atmospheric river slams California, Northwest

 San Francisco has first-ever Tornado Warning as atmospheric river slams California, Northwest

SAN FRANCISCO - A strong atmospheric river is drenching much of the West Coast with heavy rains and potentially damaging wind gusts, leaving over 150,000 without power Saturday morning.

The San Francisco Bay Area was dealing with multiple threats as the storm swept through Saturday morning – including a brief Tornado Warning. Flood Watches covered the North Bay into Northern California for expected rainfall amounts of 2-3 inches across the valleys, increasing to 5 inches in the higher elevations.

A Tornado Warning was issued for over 1 million in the heart of Downtown San Francisco just before 6 a.m. Saturday morning after Doppler Radar indicated rotation as a strong thunderstorm roared into the city.

The threat passed about 20 minutes later with no reports of any touchdowns or damage, but the storm did bring a gust of 83 mph to San Francisco International Airport.

Saturday's Tornado Warning was believed to the first one ever issued for the city of San Francisco, according to the National Weather Service.

NOAA’s Storm Prediction Center had placed the Bay Area in a Level 1 out of 5 severe weather threat through Saturday morning for potentially severe thunderstorms that could bring large hail, damaging wind gusts over 55 mph - and still a risk of an isolated tornado.

The Weather Prediction Center also has the Bay Area at a Level 2 out of 4 flash flood risk. A Flood Advisory covers the heart of Downtown San Francisco for potentially flooded roadways and underpasses.

Farther east, heavy snow is expected in the Sierra Nevada with Winter Storm Warnings in effect. As much as 8-20 inches is expected in the higher elevations. Wind gusts could reach 120 mph along the mountain ridgetops and over 45 mph in the valleys.

Weather will improve across the Bay Area and Northern California later Saturday as the storm moves inland.

For the Pacific Northwest, the storm presented a serious concern for coastal flooding amid a mix of heavy rains and strong winds.

Gusts along the Washington coast reached 62 mph in Forks and 61 mph in Hoquiam early Saturday morning where High Wind Warnings were in effect.