Flooding in Iowa, June 24 to 27, 2000

Extremely heavy rains, this time over southern Iowa, occurred during the overnight hours of June 23 and 24. another mesoscale convective system developed and moved across southern Iowa. Rains were heaviest in a small part of southern Mahaska, northwest Wapello, and northeast Monroe Counties. WSR-88D radar estimated that as much as 13.5 inches of rain may have fallen during the 24-hour period in this area, although no rain gage reports were available to help verify this estimate. The highest rain gage totals for the same 24 hours included 4.27 inches at Tracy, 5.50 inches at Ottumwa, 4.63 inches by the cooperative observers at Bussey, and 3.34 inches at Albia. Flash flooding was widespread. At one point, six counties in southern Iowa were under simultaneous Flash flood Warning. Fortunately there were no injuries or fatalities reported in the Des Moines HSA, although many roads were washed out or water covered. The extremely heavy rains did not cover a large area and much of the runoff was directly into streams feeding the lower Des Moines River, which has considerable carrying capacity. Flood stage was reached on the Des Moines River at Ottumwa in two crests. They occurred on the 24th with a crest of 12.1 feet, and on the 26th with a crest of 10.7 feet. Flood stage at Ottumwa is 10 feet. The second crest was in response to additional rains that fell on the 25th, which varied from one to two inches over the basin. A double flood crest was also reached at Bussey on Cedar Creek, which flows into the Des Moines River below Red Rock Lake, with the second crest nearly two feet over flood stage. The benefits of the wet June in terms of drought relief far outweighed the impacts from the mostly minor flooding. By month's end, only four of the nine climate districts in the state were still in a drought condition. The worst areas in the Des Moines HSA were in the northwest and west central counties, where extreme drought continued as measured by the Palmer Drought Severity Index. The statewide rainfall average, furnished by the Iowa State Climatologist's office, was 6.59 inches, or 2.17 inches above normal. This was the 19th wettest June among 128 years of Iowa weather records. The west central and northwest climate districts were the only ones to have below normal rainfall for the month. By contrast, the northeast and southeast districts were more then 200% of normal rainfall, with 8.90 inches and 8.22 inches respectively. Temperatures during the month were cool, averaging 2.2 degrees F. below normal statewide. This made it the 38th coolest June in the past 128 years.