Below is listed the tornadoes that have occurred across the NWS Chicago CWA since 1950 prior to Sunday. There had been a total of 12 before Sunday, in a total of six events (basically one such event every decade). Note that eight of the November tornadoes have been EF-2 or stronger, showing that when tornadoes do occur in November, there is a decent likelihood they will be significant (EF-2 or stronger). The primary reason for this is strong dynamics and wind field that tend to be present in the cool season (late autumn and winter), which add to a greater amount of wind shear. This is a key component to tornadoes, and the greater the wind shear the more likelihood for significant tornadoes.
November tornadoes to occur in the NWS Chicago CWA since 1950:
Late Autumn Tornado Events in the Region: