National Weather Service United States Department of Commerce


A long duration storm system brought large hail, damaging winds, and heavy rainfall to the region from the afternoon hours on May 20 through the evening of May 21. Supercell thunderstorms which developed over portions of the Tri-State area on the evening of the 20th, produced hail up to 3" in diameter in the city of Royal, IA.  Additional large hail near Elk Point, SD produced hail depths approaching 6 or more inches.  

This event also featured a strong wake low on the morning of May 21st which brought powerful winds in excess of 50-60+ mph to parts of southeast South Dakota. These winds led to additional tree damage and power outages.  Another round of storms moved into the area out of Nebraska during the evening of the 21st.  These storms lead to heavy rainfall and several warnings for high winds.

There was one tornado reported in Buena Vista county on the afternoon of May 21, north of the city of Alta, IA. No injuries or fatalities were reported, although there were three homesteads damaged.


Highest Winds
Highest Wind Gusts May 21, 2024
Photo of water standing in fields as well as a full ditch. Some of the grass is flattened where water level had been higher the previous night.
Standing Water from Heavy Rain on May 21st - Near Superior, IA
(Dickinson County EM)
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