WeatherWeather Blog


The May 21 Tornado in Adams County/Greenfield is the first EF-4 in western Iowa area in 25 years

A look at EF-4 tornadoes in our viewing area
Greenfield Iowa tornado Damage
Posted at 6:07 AM, May 31, 2024

Just before 3:00 pm on Tuesday, May 21. A tornado began in far northeast Page County, Iowa. For the next hour and fifteen minutes, the violent tornado raked through parts of Adams and Adair Counties, including over the southeast side of Greenfield (the county seat of Adair County, with a population of 2,062 residents). This tornado was responsible for snapping and twisting wind turbines in Adams County and significantly damaging numerous homes.

The damage was unfathomable in several parts of Adair County, including Greenfield. Homes were wiped off their foundations, leaving only exposed basements. Vehicles were tossed and mangled, with even some ripped apart piece by piece. When the National Weather Service surveyed the tornado in the following days, they estimated that it was of EF-4 intensity with winds between 175-185 mph.

Greenfield Damage.jpg
Example of EF-4 damage done to a home in Greenfield.

In the enhanced Fujita (EF) scale (the EF-scale is an updated version of the original Fujita (F) scale, for the history of the F and EF-scale, you can find it here), an EF-4 is the second highest classification, behind the EF-5. EF-4 tornadoes contain wind speeds between 166 and 200 mph. In an EF-4 tornado, well-constructed homes are completely swept down to their foundations. Trees are mangled and partially debarked, concrete could be ripped from roads. Cars are mangled and can be tossed hundreds of yards away. This was the damage seen in Greenfield and its vicinity.

EF-4 tornadoes are rare in the United States. Each year only sees a handful of them, between 1-3 on average. They are even rarer in eastern Nebraska and western Iowa. The last F-4 tornado in western Iowa was 25 years ago, on April 8, 1999, with a tornado also in Adams County. To learn about this tornado, you can click here.

Southern Iowa Tornadoes.JPG
Strong tornadoes went south and west of Des Moines, where two of them achieved violent strength.

Since 1950, only a handful of tornadoes in western Iowa have reached F-4 intensity. A few notable ones are several that impacted Page County in the 1950s and 1960s, of which you can read more about here. In 1973, Minden was impacted by an F-4 tornado, of which you can read about here.

F4 Tornadoes Since 1950.JPG
Every F-4 and EF-4 tornado that has crossed the viewing area since 1950.

In eastern Nebraska, F4 tornadoes are more common. A few notable examples include the Milford tornado of 1957, the Omaha tornado of 1975, the York/David City tornado of 1990, and the Pilger tornadoes of 2014.

The Greenfield tornado of May 21, 2024 has joined the hallmarks of violent tornadoes in Iowa history. The latest in a string of EF-4s for the state since 2022. In 2022, an early March tornado moved from Winterset and through the south suburbs of Des Moines. In 2023, a late March tornado hit eastern Iowa near the town of Keota. Now the Greenfield tornado continues that legacy, and brought the first violent tornado to western Iowa in 25 years.