Severe Weather In April

April has the third highest monthly total of tornadoes (155) in the United States, behind only May (276) and June (243).  The United States has averaged 1,253 tornadoes annually for the 20-year period from 1991-2010 according to NOAA.  

There have been a series of deadly tornadoes in April during that time.  An outbreak began yesterday in Texas and continues today in the southeastern United States.  The threat of severe weather caused the final round of the Masters Golf tournament to begin earlier than scheduled this morning.  A severe thunderstorm contains any of the following: 1”/+ in diameter, wind gusts of 58 mph/+ or a tornado.

2017: A severe weather outbreak occurred on April 29, with a total of 295 severe weather reports from Texas to Virginia.  Of those, 25 were tornadoes from Texas to Illinois.  Fortunately, no fatalities were reported.

2011: One of the largest severe weather outbreaks on record in the United States occurred from April 27-28.  During this two-day period, there were a total of 1,054 severe weather reports, with 307 confirmed tornadoes.  Of those, 292 tornadoes occurred on April 27 from Mississippi to New York State and claimed 230 lives.  

These tornadoes were especially powerful with four being rated as “EF-5” tornadoes on the Enhanced Fujita Scale, with wind speeds of over 200 mph.  That was the highest daily total of F5 or EF5 tornadoes since the “Super Outbreak” of 1974 when seven occurred on April 3.  The Fujita Scale was first introduced in 1971, and was updated to become the “Enhanced Fujita Scale” in 2007.

2006: A significant tornado outbreak occurred on April 2, with 86 tornadoes from Iowa to Tennessee.  The tornadoes were part of an overall severe weather outbreak that stretched from Texas to Ohio, with an overall total of almost 900 severe weather reports.  There were 11 reported fatalities during this outbreak.

2002:  Over the span of two days (April 18-19), a total of 540 cases of severe weather were reported.  Only 15 of the 540 severe weather reports were confirmed tornadoes, and none caused any fatalities.

 

It’s interesting to note that for many years hail was considered “severe” when it reached a diameter of ¾” or greater, roughly penny-sized.  However, the National Weather Service raised the criteria for severe hail to 1”/+ in diameter (quarter size) on January 5, 2010.  That was done because a determination was made that significant damage is less frequent with smaller hail.  The result is a net reduction in the overall number of severe weather warnings since 2010.  

Whenever severe weather is a possibility people should rely on their favorite local meteorologists, such as my colleagues and I on the WUSA9 Weather Team for the latest weather watches and warnings.