How rare are tornadoes in Arizona?
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The tornado that tore through the small town of Star Valley last weekend is a relatively rare event in Arizona. The state usually sees roughly four or five tornadoes each year, and every county except Greenlee has reported them.
State climatologist Erinanne Saffell said that Arizona began tracking tornadoes in the 1950s.
"Especially in the early years, before we had the Doppler Radar in 1988, it was based on if somebody’s seen the information. Can somebody see the tornado? Did they see the damage?" Saffell said.
She said that's why the most populous county, Maricopa, has the most recorded tornadoes, even though most happen in northern Arizona.
Saffell said that area has a key ingredient for tornadoes: a wind shear, which is when the wind changes direction or speed.
"If anybody has driven along I-40 when one of these systems comes through or when we have thunderstorms, you know that we can get disaster winds up in the plateau area," she said.
The strength of tornadoes is measured using the five-point EF scale. Saffell aid the strongest tornadoes recorded in Arizona had an EF-3 magnitude, which can bring winds up to 165 miles per hour. Two of them went through Coconino County in 2010.
EDITOR'S NOTE: The story has been updated to correct Erinanne Saffell's name.
