Tuesday night 2/5/08 into Wednesday 2/6/08 the deadliest cluster of tornadoes in nearly a decade tore through five Southern states. At last count the death toll was up to 50. So you may be asking yourself how common are winter tornadoes???

Well the peak tornado season runs from late winter through mid summer, but twisters can spin up at any time of the year with the right conditions. We had the perfect setup for tornadoes across the Mississippi River Valley Tuesday night. A large high pressure system off the Southeast coast brought the region unseasonably warm and moist air for February (Central VA saw record highs in the 70s). At the same time a strong cold front pushed in from the upper Midwest. This sparked off a line of severe thunderstorms. In addition the contrast between the cold air to the north and warm air to the south triggered a fast moving jet stream above the storms. This introduced wind shear (changing wind speeds both in the horizontal and vertical directions), which caused the thunderstorms to rotate. Rotating thunderstorms are called supercells and these storms typically produce the most violent tornadoes.

According to the Storm Prediction Center in Norman, OK Tuesday night’s outbreak was the nation's worst in a 24-hour period since May 3, 1999. The death toll ranks among the top 15 from tornado outbreaks since 1950. This serves as a reminder of how dangerous tornadoes are.

When tornadoes are possible in the viewing area, ABC 13 will be the first to let you know. Remember a tornado watch means tornadoes are possible, therefore continue to monitor the potential for severe weather. If a tornado is detected on radar or is spotted, a tornado warning is issued. In case a tornado warning is issued for your community - take cover immediately. Go to the basement and protect yourself using pillows and blankets under a sturdy table. If you have no basement, go to a bathroom or closet, with no windows.

Matt Ferguson

Meteorologist

mferguson@wset.com