The Midwest was hit with a major tornado outbreak on Sunday, November 17, 2013. The preliminary reports can be found on the NOAA Storm Prediction Center reports page. Below is a map showing the preliminary reports. Click on the map to go to the Storm Prediction Center Google map server to zoom in and out, etc. Additional NWS reports can be found from the Chicago office and Lincoln office. At this time, the communities hardest hit in Illinois were Pekin, Washington, and Gifford.
While the primary tornado season in Illinois is in April through June period (plot below), it is possible to experience tornadoes in any month in Illinois. In fact, the odds are slightly higher in November than in October or December. These numbers are based on a study using tornado events from 1950 to 2010 in Illinois.