May tends to be the most active severe weather month in the Miami Valley. In 2021 no tornado warnings or severe thunderstorm warnings were issued by the National Weather Service in Wilmington during the month of May.
The Wilmington Forecast office also covers an area much larger than the Miami Valley. The region includes Dayton, Cincinnati, Columbus and portions of eastern Indiana and northern Kentucky.
This is the first time since the office opened in 1994 not even one severe thunderstorm warning was issued. The current record was three severe thunderstorm warnings in 2013. There were zero tornado warnings issued in 2016, 2013, and 1994 according to data from the Iowa State University, Iowa Environmental Mesonet.
So far in 2021 the office has issued just eight severe thunderstorm warnings for the year which is currently the least amount from Jan to June. The latest, first tornado warning and confirmed tornado for the region June 12.
Several ingredients have been lacking this season. Most notably may was seasonably cooler than normal. The line separating warm and cold air masses didn’t line up in the Miami Valley like it did in 2019 when a Bermuda High settled to our SE. This pattern keeps the Miami Valley warm and moist with cooler and drier air to our west. The result was 37 Tornado warnings in May many coming during the Memorial Day Tornado Outbreak.
June continues to be one of our top three active severe weather months. It only takes one storm to turn a good season into a bad one.