John Farley
Supporter
The seasonality of the F4+ tornadoes in southern IL, as shown on Dan's map, is interesting: 2 in December, 2 in March, 1 in February, 1 in September, just one in "tornado season" (May). When I lived in that area, my first chase tornado was on December 23, 1996. That seemed like an oddity at the time, and still does to some degree, but perhaps not all that unusual in that area. Certainly very strong dynamics can occur there when winter warm spells come to an end.