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Tornado Climatology for Central and Southeast Illinois

Tornadoes have been common across central Illinois over the years, with lesser totals reported across southeast portions of the state.  The map below shows the number of tornadoes reported across the Lincoln NWS's County Warning Area between 1950 and 2011.  By clicking on any of the counties, you can get more detailed information on the tornadoes reported in those counties since 1950.

While some of the disparity can be attributed to differing weather conditions, some of it is also due to the organization of storm spotter networks, with an overall upward trend in reported tornadoes as the years progressed.  To try and account for this, we have also normalized the reports of tornadoes per 100 square miles, instead of just by county boundaries:

The image at left shows the prevailing directions that the tornadoes move from in this area.  For example, the 36% along the southwest axis of the graph means that 36% of the tornadoes moved from the southwest to the northeast.  Most of the tornadoes in this area moved toward the northeast to east.  Fewer tornadoes moved in a southeast direction.  Only a handful moved in other directions (shown in the inset at the lower right corner of the image). Click on the image to enlarge.

The database from the National Climatic Data Center (NCDC) and the Storm Prediction Center (SPC) was used to create these pages.  Besides the tornado information, NCDC's Interactive Database can be used to retrieve information regarding hail, winter storms, and other hazards.  Also check out NCDC's U.S. Tornado Climatology page, and SPC's GIS-enabled Severe Weather Climatology page.

Some other items to consider when reviewing these pages:

• Detailed storm surveys were not frequently conducted during earlier time periods.  In some cases, this resulted in apparent long tornado tracks, under the assumption tornado remained on the ground the entire time.  Also, changes in direction of movement were not well documented.
• Earlier records were sketchier in terms of touchdown locations, etc.  There may be errors of a few miles in the specific locations of touchdowns.
• The F-Scale magnitudes given are for the entire tornado track, although the peak magnitude may have only been in certain locations.