Flash Flood in Iowa, June 16 to 17, 1996

Intense thunderstorms developed in a very unstable atmosphere. Precipitable water values were over 2 inches, with K indices in the lower to middle 40s. Surface temperatures warmed into the lower 80s with dew point readings in the lower to middle 70s. The rain was tropical in nature as a warm core low at 500 mb was approaching from the west. Thunderstorms produced copious amounts of rainfall. Rainfall of 4 to 7 inches was common across northeast Boone, southern Hamilton, northern Story, and southwest Hardin Counties. Doppler radar precipitation estimates were as high as 8.5 inches in the area. Officially, the heaviest observed rainfall was 7.83 inches just sousthwest of Jewell. Nearly 7 inches /6.9/ of that fell in a 2 1/2 hour time period. Unofficial reports of 8 to 9 inches were received as well. Most of the rain fell in a three hour period between 1800 and 2100 CST. Flash flooding was widespread with numerous reports of bridges washed out and roads under water. Many highways were closed and Interstate 35 was closed for a period of time as well. Squaw Creek in Ames crested near the all time high. Crop damage was extensive as well with many fields washed out. Some of the damage included by county included: 8 homes and 3 businesses heavily damaged north of Ames in Story county. Fifteen to 20 businesses with damage in the 10s of thousands of dollars in Ames, another 15 to 20 with minor damage. Damage to roads was estimated at $200,000. In Boone County, road damage was placed around $200,000. The Governor of Iowa granted a disaster declaration for Boone, Story, Hardin, and Hamilton Counties.