San Francisco has the first ever tornado warning as the atmospheric river hits California, northwest

SAN FRANCISCO – A strong atmospheric river is drenching much of the West Coast with heavy rain and potentially damaging wind gusts, leaving over 175,000 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.

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A tornado warning was issued for over 1 million in the heart of Downtown San Francisco just before 8 p.m. 6 Saturday morning after Doppler Radar indicated rotation as a severe thunderstorm roared into the city.

The threat passed about 20 minutes later with no reports of touchdowns or damage, but the storm brought a wind 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 is believed to be the first ever issued for the city of San Francisco, according to the National Weather Service.

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

(Livermore Police Dept. / FOX Weather)

NOAA’s Storm Prediction Center had placed the Bay Area in a Level 1 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 flood risk. A Flood Advisory covers the heart of Downtown San Francisco for potentially flooded roads and underpasses.

Further 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.

Gusts could reach 120 mph along the ridge and over 45 mph in the valleys. An anemometer atop Ward Peak at Alpine Meadows Ski Resort recorded a wind gust of 159 mph Saturday morning.

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

Strong winds, coastal flooding batter western Washington

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

Wind gusts along the Washington coast reached 62 mph in Forks and 61 mph in Hoquiam early Saturday morning, when high wind warnings were in effect.

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

NWS Seattle warned of flooding 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,” warned NWS Seattle. “Low-lying property, including homes, businesses and some critical infrastructure may be flooded. Shoreline erosion or damage may occur.”

Another atmospheric flurry – what will be the third this week – is headed for the West Coast early next week, but is expected to be weaker than Saturday’s event.