April Tornado Count for the U.S., 1950–May 2011. NOAA

By Tamino
25 May 2011

Shortly after it became clear that April 2011 broke the U.S. record for the most April tornados, the Washington Post reported that it was not a “legitimate” record … yet. That’s because earlier years’ counts are adjusted upward in an attempt to compensate for our increasing ability to detect tornados in the U.S. However, it didn’t take long for April to shatter, not only the actual record of observed number of tornados, but the adjusted record as well. …

The preliminary count for April 2011 is 875 tornados, which is more than three times as many as the previous record of 267 back in 1974. Yeah, more than three times as many. This year’s April count is only preliminary, and may well be revised downward as duplicate reports are identified. But it’s still one hell of a hockey stick.

Even after the dust clears, this April is overwhelmingly likely to be a record-smasher. This is shown by a similar graph from NOAA which includes an “error range” to indicate possible final counts.

Any way you slice it, it’s still a hockey stick and 2011 will still be a new record.

Total tornados in April isn’t the only record broken this year. According to NOAA reports of 2011 tornado information, this April also broke the record for most tornados in any month, the previous record being 542 in May 2003 (May is the most active month for tornados in the U.S.). …

Year of the Twister



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