February 5, 2008, was “Super Tuesday” – the day when 23 states held at least one primary or caucus election in preparation for the Republican and Democratic National Conventions. The date proved to be “super” in another sense as a powerful system of severe thunderstorms, including tornadoes, developed from the Ohio River valley through Tennessee and into the mid-south states of Mississippi and Alabama. Eighty-two tornadoes and 59 deaths were confirmed, making the outbreak the deadliest in the U.S. since May,1985.
Alabama and Tennessee, the states hardest hit by tornadoes, both held their primaries that day. Some polling locations were forced to close early due to the severe weather; it is uncertain whether this had an effect on the outcomes of the primaries. Other Super Tuesday states that were affected by the storms included Missouri, Illinois, and Arkansas.
On February 4, 2008, forecasters noted that factors such as a group of low pressure systems, a strong cold front, a powerful upper level jet stream which split over the mid-south, and very warm, moist air ahead of the front, were gathering in the Central Plains region. This confluence of events produced almost ideal conditions for widespread severe weather, including supercell thunderstorms.
The three requirements for thunderstorms were met: moisture, a lifting force, and instability. The moisture was carried from the Gulf of Mexico all the way north into Ohio. The split in the jet stream created a vacuum effect between the two branches that lifted air from the surface. Instability was created by the collision of varied air masses – at one point a low pressure center had two dry lines, two cold fronts, and one occluded front extending from it!
Early on February 5, the National Weather Service Storm Prediction Center issued a high risk report for a large area of the central plains and the southeast. During the outbreak, 13 tornado watches and 2 severe thunderstorm watches were issued. Two of the tornado watches were deemed “particularly dangerous situations.”
The storms began to develop on a line from east Texas to Missouri, with snow farther north to Iowa and Wisconsin. As the line moved east, supercell thunderstorms began to develop in the late afternoon, when the air is the most unstable and moist. Very powerful storms hit Memphis and Jackson Tennessee, and later Nashville. An EF2 tornado traced an usually long track near Memphis, causing 4 fatalities, while Jackson experienced a group of tornadoes, including an EF4, and two fatalities. Extensive damage was produced in each case. An EF3 tornado in the Nashville area resulted in 22 deaths.
Tupelo, Mississippi saw significant tornado damage. In the early morning hours of February 6, the supercells redeveloped as the storms were over Alabama. A tornado in Lawrence County, Alabama resulted in 4 fatalities and at least 25 injuries. It was later rated as an EF4.
The storms caused intense non-tornadic damage as well. In the northern area of the low pressure system, snowstorms cause heavy snowfall and a state of emergency in the Madison, Wisconsin area. Flooding was reported from Illinois to New York due to heavy downpours. Damage from straight line winds and hail the size of softballs also occurred.
Several counties in Arkansas and Tennessee were declared federal disaster areas. Volunteers were mobilized to provide aid, and donation drives were organized by two sports teams, the Nashville Predators and the Tennessee Titans.