How rare are tornadoes in California?
Unstable air is mixing with some wind shear amid a continuing volatile weather pattern to create a risk of thunderstorms Monday into Tuesday in California -- some of which could turn not only severe but also a slight risk of a tornado.
Atmospheric river brings rare tornado risk along California coast
Monday's atmospheric river storm brings a slight risk for a tornado along the Central California coast.
SAN FRANCISCO -- With the relentless rains from a constant parade of atmospheric rivers drenching California under several inches of rain already, the last thing the area needs is severe weather.
But unstable air is mixing with some wind shear amid a continuing volatile weather pattern to create a risk of thunderstorms Monday into Tuesday in California -- some of which could turn not only severe but also a slight risk of a tornado.
FILE - A man looks at a tree that crashed into a house at 412 Manti Drive when a tornado-like wind roared through his neighborhood.
(Don Bartletti/Los Angeles Times / Getty Images)
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NOAA's Storm Prediction Center gives just a 2% chance of a tornado occurring within 25 miles of any point along the immediate central California coast on Monday and Monday night -- though that does include the San Francisco, Oakland and San Jose areas.
"That's the zone where we are most likely to see thunderstorms that can quickly rotate," says FOX Weather Meteorologist Kendall Smith. "So, we do have enough instability as well as wind shear in the atmosphere to allow for some of these thunderstorms to produce a quick spin-up tornado."
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(FOX Weather)
The risk spreads south on Tuesday into Southern California, where a similar 2% risk of a tornado within 25 miles of a location exists for the greater Los Angeles and San Diego areas.
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(FOX Weather)
The risks are minimal, but they are not zero, as it typically is in California. Still, these types of forecasts are rare. It's the first time in three years that the Bay Area has seen a similar 2% risk in January, while it's been six years since Los Angeles was under such a risk (though the northern coastal LA area had a 2% risk in 2020.)
SPC forecasters say any tornado that spins up would expect to be brief, but even a short, weak tornado can cause damage.
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Suppose a tornado were to form and was observed or caught on radar in the greater San Francisco area. In that case, it could prompt the region's first Tornado Warning in nearly 12 years, according to Iowa State Environmental Studies (though there have been more recent marine warnings for potential waterspouts offshore).
(Iowa Environmental Mesonet / Iowa State University / FOX Weather)
And there has never been a Tornado Warning issued in San Francisco.
For the Los Angeles and San Diego areas, it's been just over three years since their last Tornado Warning. Compare this to parts of the South where the Tornado Warning-less streak is less than a week old. In the Houston area, it's been since Sunday.
The longest Tornado Warning-less streak in the Lower 48 belongs to Eureka and Northern California, where it's been over 20 years. The only place longer is Alaska which has apparently never issued a Tornado Warning.
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As for Tornado Watches - which are issued by the Storm Prediction Center when tornado conditions are present – there has never been a watch issued along the West Coast.
There have been 467 reported tornado events across the large state since 1950, but while 90 people have been injured in total over the years, the state has yet to suffer a deadly tornado.