U.S. Tornadoes: The Month of April by the Numbers

Tornado season ramps up quite strongly during April, but the month is often defined by substantial outbreaks intermixed with quieter periods. Outbreaks during the month can pack an extra punch as strong winter-like systems interact with increasingly warm and humid air traveling north into and past the Gulf Coast states.

As seen in our map of county-level April tornado strikes, much of the continental U.S. has seen an April tornado, with New England notably absent except for one lone Connecticut twister. However, the April concentration of tornadoes clearly shows active zones through Alabama and Mississippi as well as up and down the Mississippi Valley. The southern Plains really lights up too, with plenty of activity from north Texas into southern Kansas.

April Tornado Stats (1950-2011)

Total tornadoes: 7,885
Climatological average (1991-2010): 154.6
10-year average (2001-2010): 163.0
Long-term average (1950-2011): 127.2
Monthly high: 759 (2011)
Monthly low: 15 (1950) / 20 (1987)
Total fatalities: 1,762
Total injuries: 28,996

The raw daily count of tornadoes shows no days below 100 over the course of 62 years as well as generally increasing numbers while the month moves on. When it comes to a more stringent — or outbreak counter-measuring — tornado day figure, the first 7 days of April average historical (1991-2010) odds around 14 percent for seeing a U.S. tornado touchdown. By the last 7 days, those odds have risen to 23 percent.

Texas holds a commanding lead for total tornadoes during the month, in part attributed to its large size and also because April and May are the peak of tornado season in the state before the zone drifts north and northwest into the summer. Moving forward from March, we see a number of interior states rise in the list though “off season” states near the Gulf Coast still remain quite active and have been home to April’s worst tornado events. Oklahoma, Illinois, Kansas, Alabama and Arkansas all join Texas in the “over 400 tornadoes club” for April since 1950.

Significant (F2/EF-2+) tornadoes made up just over 27% of April tornadoes from 1950-2011, but they caused 98% of the deaths. The deadliest tornado in April occurred on the 27th in 2011 when an EF-5 traveled from near Hamilton, Alabama to near Huntland, Tennessee. 72 perished in that tornado alone. The second deadliest in April also occurred that day when an EF-4 passed through Tuscaloosa and Birmingham.

SPC tornado data obtained at the Tornado History Project. Images can be selected for larger versions. Get updates about U.S. Tornadoes on Twitter and Facebook. Official 2012 data will be available during spring 2013.