Severe weather season on the way

Published 1:25 am Thursday, October 21, 2010

Fall severe weather season is drawing nigh, and this one could be active, according to a meteorologist at the University of Southern Alabama’s Weather Center.

Jason Holmes explained the presence of La Nina off the Pacific Coast intensifies the jet stream, which affects the intensity and track of storms.

“La Nina has not fully developed yet,” he said.

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When the cycle reaches maturity, this portion of the country, the Southeast, will see warmer temperatures and wetter weather, Holmes said.

Add to the presence of the developing climate cycle off the West Coast, the presence of the jet stream over this portion of the country, and the stage is set for severe weather especially during November and December when the jet stream, a fast flowing narrow air current in the atmosphere, dips over the Southeast on its way to the equator.

“When the jet stream comes down during the late fall and winter months, it provides a lot of energy for severe weather, if conditions are right,” Holmes said.

In the spring, the jet stream moves from south to north, causing another opportunity for severe weather in the Southeast.

That weather pattern is about to change next week. A system is expected to move into the state Monday through Wednesday with the ability to produce rain. Then, Thursday through Saturday, another storm system is expected to follow, Holmes said.

Dallas County Emergency Management interim Director Rhonda Abbot pointed out this area’s significant fall season outbreak usually begins Nov. 1 and continues through until Dec. 15.

“Since 2000, through 2009, 25 percent of Central Alabama tornadoes have occurred in the months of November or December,” she said. “Ninety-three percent of tornado-related deaths and 79 percent of tornado-related injuries in Central Alabama have occurred in the months of November and December.”

For example on Nov. 15, 2006, 14 tornadoes ripped across Alabama, including eight across Central Alabama. Of those was the notorious “Fun Zone” tornado in Montgomery, which destroyed The FunZone Skate Center and trapped children inside. All of the children were pulled out of the rubble to safety with only one needing treatment for injuries.

The largest outbreak documented in Alabama was Nov. 24-25, 2001, when 36 tornadoes raked across the state.

On Nov. 24, 2001, tornado activity shifted from Arkansas and Mississippi to Alabama about midday. That day alone, the National Weather Service in Birmingham reported 13 supercells across the state, including an F4 that moved across Blount and Etowah counties. The following day, just after midnight, a tornado touched down in Dale County.

The National Weather Service recorded four tornado-related deaths from two separate tornadoes. One was an F3 that moved from Pickens County northeast and north of Birmingham and Tuscaloosa to Walker County. Another killed two people in Cherokee County.