One of the notable climate/weather stories in Illinois this year is the tornado drought. As of September 9, the NWS has received only 20 reports for Illinois (first map). The map of Illinois includes all severe weather including tornadoes (20), hail (93), and wind damage (395). The last tornado reported in Illinois was on September 1, 2013, in LaSalle County. The report of that event is here.
The second map shows where the tornado reports were located across the US. It’s not just Illinois. Tornado reports in neighboring states were sparse as well.
The third figures shows the running annual count of tornadoes for this year and earlier years since 2005 in the United States, according to the Storm Prediction Center. At this point in time, this year has the lowest total of any year since 2005 with 725 tornado reports.
Why are the tornado numbers so low this year in Illinois? Here the spring was dominated by large, slow-moving systems that produced lots of rain but not much severe weather. Then, starting in July, we transitioned into drought conditions with little opportunity for any severe weather.
The last graph shows the historical distribution of Illinois tornadoes by month. April, May, and June are the prime months – followed by March, July, and August. Therefore, the busiest months of the tornado season have past. We generally see a few tornadoes in the fall months but not like we do in spring or summer.
The NWS Storm Prediction Center has a wonderful web site full of severe weather statistics with maps and plots at http://www.spc.noaa.gov/climo/online/