A tornado in California? Not as rare as you might think

By Christopher Weber, Associated Press

Wednesday, Jan. 11, 2017 | 2:15 p.m.

LOS ANGELES — The latest storm to wallop Northern California whipped up a small tornado that downed trees and fences near Sacramento.

Here's what you need to know about twisters in California, which occur regularly but in limited numbers and force.

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HOW BIG WAS TUESDAY'S TORNADO?

The twister that touched down south of the state capital registered EF0, at the lowest edge of the tornado scale that goes up to EF5. The Enhanced Fujita (EF) scale measures the intensity of tornadoes in the U.S. and Canada based on damage caused.

No injuries were reported from the tornado, which was on the ground for 3/8 of a mile and carved a path of minor damage about 100 yards wide, according to National Weather Service meteorologist David Rowe.

"It came as a little bit of a surprise considering that we're so focused on all the heavy snow and rain," Rowe said.

Most California twisters are in the EF0-EF1 range and are less damaging and deadly than their Midwest counterparts. The strongest ever recorded in California were EF3s — one in Riverside County in Aug. 1973 and another in Orange County in Feb. 1978

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HOW COMMON ARE TORNADOES IN CALIFORNIA?

Of the 1,000-or-so tornadoes that annually strike the United States, about 11 occur in California, according to the American Meteorological Society.

Thirteen roared through in 2005, more than Oklahoma that year.

In October 2012, five tornadoes touched down in north central California, damaging dozens of homes and a handful of commercial buildings.

That event marked the highest number of tornadoes in one day for California since April Fool's Day in 1996, when five tornadoes flattened trees and barns near the north central city of Stockton.

California tornadoes are most common in wide open spaces in the state's Central Valley, the agricultural heartland where the terrain is similar to that of the Great Plains.

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WHAT CAUSES TORNADOES?

Tuesday's twister accompanied a powerful line of thunderstorms and followed days of volatile weather, said National Weather Service meteorologist Travis Wilson.

They were ideal conditions for creating twisters. When cooler air is forced aloft, wind speeds tend to increase and that can cause tornadoes, Wilson said.