Based on data from the NOAA Storm Prediction Center, there have been 46 tornado reports in Illinois in 2010, as of September 14. These reports are based on damage at a particular site. The real number of tornadoes is often less than the first reports, as further analysis may show that the same tornado produced damage in two or more locations.
Most of the tornado activity for 2010 occurred in June with 39 reports (figure below). Many of those occurred in tornado outbreaks on June 5 (SPC report) and 21 (SPC report).
Of course, the 2010 tornado season is not over yet. The climatology of tornadoes in Illinois shows that it is possible to have tornado activity somewhere in the state all the way through December.
Tropical Storm Hermine Reaches Illinois
The remains of Tropical Storm Hermine have reached Illinois this morning. Rainfall amounts of 1 to 3 inches are possible and flash flood warnings have been issued. Check the National Weather Service as this event unfolds.
While we don’t often use the words “tropical” and “Illinois” in the same sentence, the remains of tropical storms and hurricanes have reached us before. Most of these systems came on shore in Texas and Louisiana and weakened considerably as they moved northward. Usually, the severe weather is gone by the time they reach Illinois but they can produce large amounts of rain than can lead to flooding.
The passage of four tropical systems alleviated drought impacts, particularly in southern and central Illinois during the 2005 growing season. The four systems were Tropical Storm Arlene, and Hurricanes Dennis, Katrina, and Rita. An article in the Illinois State Academy of Science by me described that situation in more detail.
More recently, in September 2008 the remains of Hurricanes Ike and Gustav produced heavy rains and flooding in Illinois. More on that particular situation can be found on my website.
Summer – One of the Warmest and Wettest on Record
Summer
This summer was one of the warmest and wettest in Illinois history, based on preliminary data. The average statewide temperature for this summer (June-August) was 76.4 degrees, 2.7 degrees above normal and the seventh warmest summer on record. The average statewide rainfall was 16.7 inches, 5.2 inches above normal and the sixth wettest summer on record. Statewide records for Illinois extend back to 1895.
August
The average statewide temperature for August was 76.8 degrees, 3.2 degrees above normal. That puts it at the 13th warmest August on record. August was on track to being even warmer but a late-month cool spell knocked it down a few notches in the ranking. August rainfall has been close to normal with a statewide average of 3.4 inches, just 0.3 inches below normal.
[This is an update of a post earlier in August, now removed to avoid confusion]