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May's 10 Worst Tornado Outbreaks

Nick Wiltgen
Published: May 1, 2013

May: Peak Month for Tornadoes

After four consecutive years in which May has not been the top tornado month, it may be easy to forget that over the long term, May is the king of the tornado calendar.

Over the 30-year period from 1982 through 2011, May averaged 255 tornadoes per month, followed by June with 221 and April with 158.

But when it comes to individual tornado outbreaks, April is the month that has attracted the most attention. Both the 1974 Superoutbreak and the 2011 Superoutbreak took place in April.

May, however, has its share of major tornado outbreaks. Some are recent, and some you will undoubtedly remember. Others may surprise you, or may have occurred before you were born.

Our rankings come from our severe weather expert, Dr. Greg Forbes, whose Forbes Impact Index is a sophisticated combination of tornado counts, tornado sizes and intensities, casualties, damage, and geographical extent for major historical tornado outbreaks. The Forbes index accounts for changes in dollar inflation (up), annual tornado reports (up), and annual tornado fatalities (down) over time to enable, as closely as possible, an apples-to-apples comparison of various outbreaks.

Our list begins with the oldest tornado outbreak to make the top ten.


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