By Dan Klepal
Enquirer staff writer

The Queen City ranks 12th of 20 large cities considered most prone to being hit by a twister. Since 1950, 54 twisters have hit the region.

The list was compiled by VorTek, an Alabama company that developed software to predict the threat of tornadoes based on 54 years of history taken from the National Weather Service. It considers a 20-mile radius around cities with populations in excess of 100,000.

That means the threat of a tornado to Cincinnati also includes Northern Kentucky and Southeast Indiana.

The company also ranks states that are most prone for tornadoes, with Indiana ranking sixth, Ohio 15th and Kentucky 17th. The top three are Nebraska, Georgia and Oklahoma.

In the Ohio River Valley, tornado "season" is considered to be April through July. But meteorologists with the National Weather Service say tornadoes can strike any time.

For example, a tornado hit Circleville in October 1999 and Xenia in September 2001. Five twisters also have struck Greater Cincinnati in the off-season, between September and November, the last of which happened in November 1981.

"Tornado awareness is considered a valuable means by which you can reduce the loss of life," said Frank Tatom, an engineer of atmospheric science for VorTek.

Mike Gallagher, a meteorologist with the National Weather Service in Wilmington, said May through July is the "peak" time for tornadoes in Greater Cincinnati. That's when warm, moist air from the south collides with cooler air from the north.

Gallagher's assessment matches data that shows April and June are the most tornado-prone months in Greater Cincinnati.

E-mail dklepal@enquirer.com