A flash flood was caused by 3 or more inches of rain in less than an hour. Many basements were flooded and left with mud and debris.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS FSD wrote it up.
A flash flood was caused by 3 or more inches of rain in less than an hour. Many basements were flooded and left with mud and debris. Some foundations and basement walls collapsed, mainly in Sioux City. Many roads were flooded, at one intersection to a depth of eight feet, damaging vehicles by the water and debris. The flooding brought down some trees, and damaged some of the flooded streets as water undercut them. A motorist caught in the flooding and the firefighter who rescued him were treated at a hospital for hypothermia. The flooding caused crop damage in the countryside, but the amount of crop damage was not determined.
The Omaha radar (KOAX), 122 km away, was scanning. The volume nearest the first event began at 14:57 UTC.
1 flash flood. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 1999Every state in 1999This day in weather historyWarnings in Iowa, July 1999
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5711980.