Thursday was an interesting weather day in Illinois. Many areas experienced a rapid melt of the snowpack as warm, humid air moved into Illinois. The by-products of this included heavy fog, rain, severe weather, and localized flooding. I was driving back from a meeting in Pittsfield and was chased by severe thunderstorms and tornado warnings all the way back to Champaign. As I approached Champaign, the visibility on Interstate 72 dropped to 20-40 feet as the warm, moist air blowing over the cold, snowy fields produced heavy fog.
Below is a map of the preliminary storm reports for Thursday, including several possible tornadoes in Illinois. Click on the map to link to the reports from the NOAA Storm Prediction Center.
February tornadoes are relatively rare but they do happen. The second graph is from a study of 2,239 tornado reports in Illinois (link to more plots). Of those, just 1.3 percent occurred in February. However, one event that occurred after that study was the deadly Harrisburg tornado that killed 8 people on February 29, 2012.
