This year has been a somewhat quiet one in terms of severe weather so far. One way to understand how this year’s severe weather activity is below average is by looking at the total number of Severe Thunderstorm and Tornado Watches issued by the National Weather Service’s Storm Prediction Center. As of Monday, May 14th, only 90 watches have been issued- the fewest within the past century. Typically by this time of the year about 200 watches are issued.
This correlates with the number of tornado, wind, and hail reports this year. All of these reports are below the 10-year average from 2005 through 2015. For tornadoes, 322 tornado reports is well below the year-to-date average of 613 tornadoes. This year’s tornado count also falls below the 25th percentile in terms of year-to-date tornado count ranks, which factors in the tornado counts from 1954 through 2007. The record lowest tornado count through this time of the year is 140.
Just because the Severe Thunderstorm and Tornado Watches count has been lower than normal, the same for severe weather reports, that doesn’t mean it will remain below average through the end of 2018. In 2010, only 386 tornadoes were reported through May 13th, but the yearly total ended at 1525 tornadoes, which is above the average of 1402.
The key point is that despite a below average start to the severe weather season, it’s important to stay alert because the outcome could certainly change later this year.