Active year for tornadoes

The National Weather Service in Chicago covers the following counties:  Boone, Cook, DeKalb, DuPage, Ford, Grundy, Iroquois, Kane, Kankakee, Kendall, Lake, La Salle, Lee, Livingston, McHenry, Ogle, Will and Winnebago.

As of August 27th, 2015, a record number of tornadoes have occurred within the warning area of the Chicago National Weather Service.  According to the weather service, the four tornadoes that occurred on August 18th, 2015 brought the yearly total up to 29.  This breaks the old yearly record for tornadoes in their warning area of 27, set back in 2004. 

With the advancement of Doppler radar in 1992, dual polarization in 2012, and the development of the spotter network in northern Illinois, the ability to not only detect, but to actually visually confirm smaller tornadoes that may have otherwise gone unnoticed has increased.  It's also interesting to see the past two years, 2014 and 2013, also within the top ten.