NU Online News Service, March 16, 1:06 p.m.EDT

Although this year's tornado season has begun slowly, weatherexperts suggest that winters comparable to 2009-2010 have typicallyproduced an above average number of tornadoes the following spring,an industry group warned.

The Institute for Business & Home Safety (IBHS) cautionedthat with an El Nino winter almost behind us, it is time to startpreparing for what forecasters predict will be an active spring fortornadoes.

Typically, the period between February and July is the mostactive time for tornadoes, and several states have designated todayas Tornado Preparedness Day, IBHS said.

"As the southern and plains states heat up this spring, so willthe chances for severe thunderstorms, including tornadoes," saidJulie Rochman, IBHS president and chief executive officer in astatement. "Even relatively isolated tornadoes can be an incrediblydestructive force of nature. The time to prepare is now - beforetornado season is in full swing," she said.

At least five homes were destroyed after a tornado touched downin western Oklahoma on March 8, authorities said. There were noreports of injuries. Other homes were damaged, and power was out toabout 900 residences in and around the city of Hammon in RogerMills County, Oklahoma.

Tornadoes are rated according to the Enhanced Fujita (EF) Scale(an upgrade to the older Fujita Scale). An EF0 with winds rangingfrom 65 to 85 mph might damage trees and small buildings but it isnot likely to cause substantial damage to structures.

An EF5, on the other hand, with winds in excess of 200 mph cantear buildings off their foundations. The positive news is thatonly a small percentage of tornadoes have winds in the EF3 throughEF5 categories, said IBHS.

When a tornado warning has been issued, or conditions appearthreatening, it is important to move to a safe place quickly."While actual warning times for weaker tornadoes can be quiteshort, the National Weather Service warning tools have advanced tothe point where warning times are averaging well over five to 10minutes for more intense tornadoes," Ms. Rochman said.

She advised that making sure one has a working weather radio andidentifying in advance the safest place to go are two excellentways to prepare for a tornado

"Without a doubt, the safest place to wait out the storm wouldbe an actual tornado shelter that has been built to meet eitherFederal Emergency Management Agency (FEMA) requirements or theInternational Code Council's ICC 500 standard," said Tim Reinhold,senior vice president of research and chief engineer at IBHS.

"When that kind of shelter is not available, the next bestoption would be a small, windowless room located near the middle ofthe building," Mr. Reinhold advised.