Case studies throughout weather circles both at the National Weather Service, Storm Prediction Center and many college university graduate program have yielded so much information on severe weather and the "perfect" storm scenerio.
While I could spend a week talking about the specifics of the event (read more here), let's briefly mention the stats so that you can visualize the enormity of this single event.
From 7PM April 3rd to 7AM April 4th 18 hours), 148 tornadoes touched down. Of those 148 tornadoes, 30 were F4 and F5 intensity . One of the F5 tornadoes hit Xenia, Ohio wiping a good portion of the town off of the map. Tornadoes were reported from southern Michigan to Winsor, Ontario to northern Alabama. All told, close to 330 people were killed with more than 5000 injured. The tornado had wind speeds of more than 300 miles per hour with a path of more than 1/2 mile wide. It stayed on the ground for more than 30 miles.
I believe that it is more than a coincidence that there was a STRONG LA NINA pattern that spring. Typically, LA NINA patterns contribute to more severe weather across the central plains and ohio valley. LA NINA doesn't necessarily mean more tornadoes but it does heavily contribute to a continental pattern that is more favorible for thunderstorms and severe weather. If the La Nina didn't exist that year, the tornado outbreak might not have happened to this degree.
A few March 2009 recap notes:
* This March was the least snowiest March since 1950. * Last winter, our last measureable snowfall occurred on March 22nd. * This March was a whopping 10 DEGREES WARMER than last March
Scott's World of Weather Archive:
-- Northeastern Ohio Lake Effect - Why Does It Vary So Much?
A Sneak Peak At Spring
