Tornado-free zone? Iowa sets calmness record

Although Minnesota had its first tornadoes of the year Friday, Iowa continues to set a tornado-free record with each day.

Through Friday, Iowa had gone 358 days with exactly zero tornadoes. None. Nada. Zippo. Zed.

Its last tornado was May 24, 2012. The previous record was 356 days, a stretch from May 5, 1955, to April 26, 1956.

The record comes during a long-running rise in annual tornado counts, generally attributed to more people looking for them. But it was also part of an extremely quiet period nationally.

Seven people were killed by tornadoes in the United States from May 2012, through April, the second-lowest figure in more than 125 years, according to Harold Brooks, research meteorologist with the National Severe Storms Laboratory. However, six people were killed by tornadoes in Texas on Thursday. No one was injured Friday in Minnesota, where tornadoes touched down near Lakefield and Wilder in the state's southwest corner.

Minnesota wasn't close to record territory before Friday, since there were four tornadoes Nov. 10 — rare in their own right for occurring so late in the year. June is the peak month for tornadoes in Minnesota, but they are frequent in May and April, and occasionally occur in March.

The lingering wintry weather has worked against tornadoes in Minnesota so far this spring, as did dry weather in the second half of last summer, said assistant state climatologist Pete Boulay.

"There's no way to know, and a late start doesn't really predict anything in terms of how the season will go," Krause said. "To go [through May 16 without a tornado] is not unusual, either. In 2010, we barely had any before June 17, and then we had 48 in one day."

Minnesota's longest known tornado-free period was longer than Iowa's current run: from June 15, 1950, to June 19, 1951. A more recent long one, Krause pointed out, covered the 11 months from July 17, 1991, to June 16, 1992, ending when an F5 tornado — the last one to hit Minnesota — killed one person and destroyed 75 homes in Chandler. Minnesota led the nation in 2010 with 113 tornadoes. There were 31 in 2011 and 37 last year.