San Francisco has first-ever Tornado Warning as atmospheric river ...

SAN FRANCISCO - A strong atmospheric river is drenching much of the West Coast with heavy rains and potentially damaging wind gusts, leaving over 275,000 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 initial reports of any touchdowns or damage. However, NWS meteorologists say they are sending a storm survey team out across the greater San Francisco area Saturday afternoon to check on possible storm and/or tornado damage in Golden Gate Park, the Richmond District and Crissy Field. 

The storm did bring a gust of 83 mph to San Francisco International Airport - believed to be the fourth-highest gust ever recorded at the airport. Gusts reached 78 mph in Monterey and 59 mph in Oakland. 

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

A road is flooded in Livermore, California on Dec. 14, 2024.

(Livermore Police Dept. / FOX Weather)

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. A wind gauge atop Ward Peak at Alpine Meadows Ski Resort clocked a gust of 159 mph Saturday morning.

 

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

Strong winds, coastal flooding pummel western Washington

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.

A dangerous combination of pounding surf of 20-23 feet, extreme spring tides, and low atmospheric pressure threatened significant storm surge and coastal flooding.

Coastal Flood Alerts

NWS Seattle warned of floodwaters reaching 2.5-3.5 feet deep along shorelines and low-lying areas during high tide late Saturday morning.

"This is expected to lead to numerous road closures," NWS Seattle warned. "Low lying property including homes, businesses, and some critical infrastructure may be inundated. Shoreline erosion or damage may occur."

Another atmospheric river — what will be the third in the week — is heading to the West Coast early next week but is expected to be weaker than Saturday’s event.