Updated December 1st - Preliminary 2009 Wisconsin Tornado Count

Through December 1, 2009, only 16 weak (EF0 or EF1) tornadoes have been documented in Wisconsin this calendar year.  This is below the yearly average of 21 tornadoes.

Here's a simple listing and plot of the location of the 16  tornadoes (click on table for larger version)...


Below is a simple plot of the locations of the 16 tornadoes in Wisconsin for 2009 (click on table for larger version):


2009 wi tor plot

In fact, as most of you have sensed, the 2009 severe weather season in Wisconsin was "below average" - the number of tornadoes, damaging wind events, large hail events, and flash flooding events were all below normal.  For much of the spring and summer season, the storm track has kept most ot the stronger storms in the area from Wyoming and the Dakotas over to Iowa and Illinois. Most of Wisconsin's severe weather in 2009 occurred during the period of June 18th through the 27th.  However, things got a little busy for July 23rd, July 24th, and July 27th when damaging tornadoes, thunderstorm winds, large hail, and flash floods raked parts of southern Wisconsin.  August 8th. 9th, and 19th were also somewhat busy.

Below is a simple table showing the average number of tornadoes in Wisconsin by month.  On a yearly basis, Wisconsin averages 21 (20.5 to be exact, based on official 1971-2000 numbers).  Wisconsin has had tornadoes in November, December, and January - however the numbers are so few that they don't show up in the monthly averages shown in the table. 

WI Monthly Tornado Numbers

Below is a bargraph showing the total number of tornadoes documented in Wisconsin by year for the period of 1960 to 2008.  As you can see, the yearly numbers are up and down, depending on the storm track.  In 2005, the National Weather Service documented 62 tornadoes in Wisconsin, which is the highest yearly total.

WI Monthly Tor count 1960-2008

Below is a simple graph showing the monthly tornado breakdown for Wisconsin for the period of 1844 through 2008.  Prior to 1950, documentation of tornaodes wasn't as precise as it is today - so a number of tornadoes were never documented.

WI tor count by month

Below is a simple table showing the breakdown of Wisconsin's tornadoes by intensity, or EF-Scale (used to be called F-Scale), for the period of  1982 through 2008.  The NWS started to systematically classify tornado intensity in 1982 on a national basis.

WI tor intensity by year

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