Tornadoes, Severe Storms Kill at Least 91 in U.S.; Missouri Is Hit Hardest

A second deadly outbreak of tornadoes in less than a month swept across the Midwest yesterday, causing damage from Wisconsin to Texas and killing at least 91 people. Severe weather probably will continue through the week.

In Joplin, Missouri, 89 people are confirmed dead, according to the Associated Press, citing local emergency officials at a press conference today. At least one person was killed in Minneapolis yesterday and another in Kansas on May 21, according to the U.S. Storm Prediction Center in Norman, Oklahoma.

“I would be surprised if there is a day this week where there wasn’t a tornado report,” said Dave Samuel, senior meteorologist at AccuWeather Inc. in State College, Pennsylvania. “There is going to be a nasty storm Tuesday through Thursday. I don’t see any big break coming.”

The outbreak comes about a month after at least 305 tornadoes tore through the U.S. South, killing 327 people, mostly in Alabama, the National Oceanic and Atmospheric Administration said. The damage from the storms April 25 to April 27 was estimated to be as much as $5 billion, according to catastrophic risk modeler Eqecat Inc. in Oakland, California.

Yesterday’s tornadoes weren’t as severe as those that rampaged across the South last month, Samuel said. The tornado in Joplin just hit “the wrong spot,” he said.

Hospital Hit

The half-mile wide tornado tore through Joplin, about 290 miles southwest of St. Louis, at 6 p.m. yesterday, destroying and damaging many homes and buildings, including St. John’s Regional Medical Center, according to state and local agencies.

Mike Woolston, mayor of the city of 50,000, declared a local disaster, according to Joplin’s website. Missouri Governor Jay Nixon declared a state of emergency and sent National Guard troops to help, according to a statement.

This year’s severe storms are the result of warm moist air from the Gulf of Mexico clashing with cooler air across the northern U.S., Samuel said.

The Gulf of Mexico is 3 degrees Fahrenheit (1.6 Celsius) warmer than pre-1970 levels, which means it can carry 12 percent more moisture, said Kevin Trenberth, distinguished senior scientist at the National Center for Atmospheric Research in Boulder, Colorado.

“Two degrees of that can be attributed to natural variability while one degree Fahrenheit is associated with climate change,” Trenberth said. “Some part of it is global warming-climate change and some part is natural variability.”

La Nina’s Influence

He said the La Nina phenomenon, a cooling of the Pacific Ocean, is also still focusing the storm track across the U.S. “just the right distance from the Gulf” to enhance tornado and severe thunderstorm development.

The Gulf moisture has also meant more rain than normal across the U.S. The Mississippi and Ohio rivers have set flooding records this year from Illinois to Louisiana.

“There has been enough rain in this event that there will probably be another bubble that will go down the Mississippi as well,” Trenberth said.

A severe thunderstorm watch, meaning the violent storms are possible, is in effect for southwestern Missouri and parts of Oklahoma and Kansas through 1 p.m. local time today, according to the National Weather Service. A flash flood warning has also been issued for the area around Joplin.

The area also has a moderate risk of thunderstorms and tornadoes tomorrow, according to the Storm Prediction Center.

Interstate Closed

Interstate 44 was closed in both directions late yesterday because of the storms. The eastbound lanes of the highway, which runs from St. Louis to Texas, are still closed, according to the Missouri Department of Transportation website.

Several cars and trucks were flipped off the highway near Jasper, Missouri, according to Storm Prediction Center damage reports. Thirty empty trailers and two tractors were damaged or destroyed at Con-way Truckload in Joplin, according to a company statement.

More than 600 tornadoes formed in all of April, compared with the previous April record of 267 set in 1974, the agency said in a statement earlier this month. That makes April 2011 the most active month ever, breaking the record of 542 tornadoes in May 2003.

As of May 17, 1,076 tornado reports have been received by the Storm Prediction Center, according to its website. Those storms have yet to be confirmed by U.S. weather experts.

On average, about 1,300 tornadoes hit the U.S. each year, according to NOAA.

The deadliest year in the U.S. was 1925, when 794 people were killed, according to NOAA.

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net.

To contact the editor responsible for this story: Dan Stets at dstets@bloomberg.net

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