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Thu. Jul 18th, 2024

How many, how strong and how deadly they have been

By Vaseline May30,2024

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  • National Weather Service data going back to 1950 shows that to that date there have never been more tornadoes than in 2024.
  • This was also one of Iowa’s deadliest tornado seasons on record, with six fatalities.
  • Despite the increased frequency of tornadoes, their severity is comparable to previous years.

May 30 marks almost a week since a tornado touched down in Iowa.

But given the frequency with which the state was bombarded with tornadoes in May, you might think it lasted longer.

Strings of strong storms — including at least one that invoked the term “derecho” that has been top of mind for some since 2020 — regularly battered Iowa throughout the month of May.

The result is a tornado season already in the record books — and, with seven months left in 2024, a year that could be Iowa’s most on record for twisters.

How many tornadoes have hit Iowa so far in 2024?

It takes some time for the National Weather Service to verify and confirm tornado reports, including extensive on-site surveys of the damage a potential tornado may have caused. The full number of tornadoes from recent outbreaks may not be fully known for several months.

But the data we have so far paints a historic picture: At least 80 tornadoes have hit Iowa so far in 2024, according to event summaries from weather agencies in Omaha, Sioux Falls, Des Moines and the Quad Cities.

Since 1950 — as far back as the National Weather Service tornado archives go — Iowa had never seen 80 tornadoes in the first five months of the year.

That count exceeds the previous January-May mark of 64 in 2004. (Iowa typically has about 19 tornadoes each year through May.)

In fact, 2024 is already among the top 10 most tornado years in Iowa history.

The state is not yet in danger of breaking that shameful record; there is still a long way to go to reach the 146 tornadoes recorded in 2021, most of which occurred during the derecho event in mid-December of that year.

Have the tornadoes been stronger this year?

Several particularly severe tornadoes stand out among the 80 to hit Iowa to date, including an EF-4 tornado that struck Greenfield on May 21 and an EF-3 tornado that struck Minden on April 26.

The EF scale, or Enhanced Fujita scale, is a way to measure the strength of a tornado based on the estimated damage in the storm’s aftermath. The weather service’s damage surveys can be used to estimate wind speeds for tornadoes.

The Minden tornado was estimated to have wind speeds of about 165 mph; the Greenfield tornado was estimated between 200 and 300 miles per hour at its strongest.

It is not unusual for Iowa as a whole to experience an EF-4 tornado at some point during the year. This is the third year in a row that at least one lands in the state.

More: ‘Somehow I’m here’: Neighbors say four people died in powerful tornado in Greenfield

The five EF-3 tornadoes so far this year are the most in a calendar year since 1999, when the original Fujita scale was still in use. (It was adapted to the EF scale in 2007.)

More: Years of recovery for Minden: ‘Hard to believe’ what the tornado destroyed is still intact

Although there have been slightly more EF-1 tornadoes and slightly fewer EF-2 and EF-0 tornadoes in 2024, the range of tornado strengths reported so far this year is roughly consistent with historical data.

This has already been one of the deadliest tornado seasons on record in Iowa

The weather service says six people have died in Iowa so far this year as a result of tornadoes, including five in the EF-4 that struck Greenfield on May 21. That makes this Iowa’s fifth deadliest tornado season since 1950.

Only four other times have more than six tornado-related deaths been reported:

  • In 2022, when an EF-4 tornado near Winterset killed six people and another death was reported in Chariton;
  • In 2008, when the state’s last EF-5 tornado struck Parkersburg, resulting in nine of the year’s thirteen tornado fatalities;
  • In 1979, when tornadoes killed seven;
  • And in 1968, when 18 people died during a May 15 outbreak that spawned five F-5 tornadoes.

The 40 tornado-related injuries reported so far this year are also among the most recent memories: Not since 2008 have there been this many tornado-related injuries in a single calendar year.

Tim Webber is a data visualization specialist for the Register. Reach him at [email protected] and on Twitter at @HelloTimWebber.

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