Tornado season deadliest in a decade
By William M. Welch, USA TODAY
May 11, 2008

The USA has been ravaged through mid-May by a near-record number of tornadoes that has pushed the death toll — including 47 killer twisters over the weekend — to a 10-year high.

The deaths of 98 people attributed to tornadoes this year has made 2008 the deadliest year thus far for tornadoes since 1998 and the seventh deadliest since modern recordkeeping began in 1950, The Weather Channel said.

Such a rate could make 2008 the year with the most tornadoes since 1950.

"We are on a pace that continues a record number" of twisters, said Greg Forbes, severe weather expert at The Weather Channel.

Violent storms over the weekend that spawned tornadoes left at least 22 people dead from the southern Plains states eastward to Georgia, including seven deaths in the tiny town of Picher, Okla., and 10 deaths in nearby Seneca, Okla.

Storms remained active Sunday night as they swept eastward. The National Weather Service said tornado watches were in effect for southern Georgia into northern Florida, as well as south central Virginia, much of North Carolina and northern South Carolina.

The National Weather Service takes weeks to confirm actual numbers of tornadoes but The Weather Channel said it believes there were 47 separate twisters as of May 11 putting the count for the year at 636. That is second only to the No. 1 year of 1999, when 669 tornadoes hit through the same date, Forbes said.

As for deaths by tornado, this year has seen the most through May 11 since 115 were killed by tornado in 1998, Forbes said. That year ended with 130 total deaths because of tornadoes.

Meteorologists say wind conditions and weather patterns have been ideal for creating twisters this year.

The jet stream, a shifting river of air at high altitudes, has been moving from the southwestern USA toward the Great Lakes and pulling moist air from the Gulf of Mexico.

The contrast between the warm southern air and cold air aloft creates winds that can spin turn into twisters.

"We've had a very strong contrast in temperatures with cold air from the north, warm moist air from the Gulf of Mexico, and with that clash of air masses … (it) produces tornado outbreaks," said Andrew Orrison, meteorologist at the National Weather Service's national office at Camp Springs, Md.

Tornado season generally begins late winter and lasts through mid-summer. May is peak tornado period for the Southeast; the season then cranks up through July in the upper Midwest and northern Plains states.

Some southern states have been particularly hard hit this year.

Before this weekend's storms, Forbes said Mississippi already had 49 tornadoes, exceeding the average over the past decade of 39 twisters for the entire year.

Alabama has had 45 twisters, exceeding its yearly average of 42, and Arkansas has had 49, already above its annual average of 48, Forbes said.

"We have quite a few states already above average for the year, and obviously the year is not nearly done," Forbes said.

Original article: USA Today
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