April EF-4 Tornadoes Rare in Illinois

According to the National Weather Service report on the April 9, 2015, tornadoes, the tornado that tracked through Fairdale was rated EF-4 on the Enhanced Fujita scale. This would be the first EF-4 tornado in April since 1981 for Illinois and only the 33rd in Illinois history, regardless of month, since reliable records began in 1950.

According to the NWS Storm Prediction Center database, only 33 F/EF-4 tornadoes have struck Illinois since 1950. Even more rare, only 8 have hit Illinois in April. Of those eight in April, six struck in the 1960s, one in 1981, and one in 2015:

Here are all the F/EF-4 tracks for Illinois from 1950-2014, from the MRCC tornado tracker tool. Unfortunately, we cannot screen out just the April events at this time. While this is a screenshot of the tool, the actual tool allows you to zoom in and out. If you point to a track then you get a pop up window with the details of that track. Check out the tornado tracker tool – it’s free.

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Washington IL EF-4 Strongest on Record in November for Illinois

Based on the evidence so far, the Washington IL EF-4 tornado is the strongest November tornado on record for Illinois since modern records began in 1950. 

The EF-3 tornado in Gifford is possibly only the third tornado of that magnitude since 1950.

One of the other EF-3 tornadoes occurred on November 15, 1988, in Madison and St. Clair Counties. The other EF-3 tornado occurred on November 19, 1991 in Marion (Williamson County). There is some confusion about this event. While it is listed as an EF-3 in the NOAA Storm Prediction Center database, the Marion History Preservation site stated that at one point the NWS declared it to be a microburst. Another source said it was later decided to be an EF-3 tornado. I am going to consider the Storm Prediction Center database as the final word on that one. 

Using a database from the NOAA Storm Prediction Center, I found 62 tornado reports from 1950 to 2012 for November in Illinois. Here is the breakdown by Enhanced Fujita-scale and the earlier Fujita-scale:

  1. EF-0: 19 cases
  2. EF-1: 23 cases
  3. EF-2: 18 cases
  4. EF-3: 2 cases
  5. EF-4: 0 cases
  6. EF-5: 0 cases

Note #1: older tornadoes were rated using the original Fujita damage scale. In 2007, the NWS has shifted to an Enhanced Fujita damage scale. Even though the damage assessments have changed to include more information, the intent is to still allow comparisons between older and newer tornado events.  For the sake of this post, I am using the term “EF” to refer to tornado strength in both the original and enhanced Fujita scale. 

Note #2: the 62 tornadoes in November for Illinois in this Storm Prediction Center database is lower than the 68 tornadoes in November for Illinois found in an earlier study from 1950-2010 using data from the National Climatic Data Center.