EF4 tornado in Adair County, Iowa

This large and violent tornado entered into south central Adair County from Adams County. The tornado remained a multi-vortex circulation as it moved into the county producing high end damage for much of its remaining path. The tornado encountered several houses in the vicinity of Fontanelle Road and 320th Street. Many of the structures received at least EF2 damage with one house north of the intersection receiving up to EF4 damage with a sufficiently anchored structure destroyed and slumped into a debris field nearby. Additional EF4 damage was noted at a farmstead on Jordan Avenue south of 280th Street with the house destroyed and trees chewed down to only the largest trucks and portions of the bark removed. The path then passed through another wind mill area with additional turbines collapsing west of Kent Avenue. The tornado then passed over Nodaway Park Ponds and entered the southwest side of Greenfield along SW 3rd Street. Several structures over the next several blocks had up to EF4 damage from SW 3rd Street over the SE 3rd Street and South of Linn Street and north of Oak and Noble Streets. Most of these saw complete destruction of the house with much of the debris scattered in the area but not completely swept away. The tornado weakened slightly for the later half of the destructive path through Greenfield. EF3 damage was widespread from SE Kent Street and SE 4th Street to the Intersection of E Iowa Street and NE 8th Street. The tornado exited the east side of Greenfield near the Adair County Fairgrounds. The tornado continued east northeast and gradually weakened impacting a few more houses before dissipating just south of the intersection of 220th Street and Quebec Avenue. This tornado produced at least 35 injuries in addition to 4 deaths within Greenfield. All of the deaths occurred in homes. Of note, according to media reports, a Doppler on Wheels (DOW) intercept research team measured a wind speed of just over 300 mph approximately 150 feet above ground level with this tornado.

PLEASE NOTE, for hail, wind, heavy rain and flooding, please see separate Storm Data entry for May 20-22.

Numerous tornadoes occurred on this day with numerous injuries and four fatalities at Greenfield in Adair County.

Multiple rounds of thunderstorms brought torrential rainfall, damaging winds, hail and destructive tornadoes to the state. These thunderstorms were the result of a low pressure system which lifted north into the area on the night of May 20th, 2024, producing slow moving storms that dropped 2 to 4 inches of rainfall. This resulted in flash flooding over portions of northern and central Iowa through the morning of May 21st, 2024.

Following the heavy rainfall through the morning, skies cleared out ahead of an approaching cold front. By the afternoon hours of May 21st, 2024, this cold front produced a line of strong thunderstorms which produced multiple strong tornadoes throughout the state, including one which led to significant damage in the town of Greenfield, IA, among other locations. This line of storms also produced damaging winds, leading to widespread tree damage and power outages throughout the forecast area.