Flooding in Iowa, April 22 to 27, 1999

Another strong low pressure system moved across Kansas and Missouri on the 21st and 22nd. This system brought moderate to heavy rainfall to the Des Moines HSA. In the overnight hours of 21 April, heavy rains fell in the extreme upper end of the North Raccoon River basin. Radar estimates were inflated by a factor of two on the rainfall amounts, with actual rainfall close to 2 inches. A widespread area of one to one and one half inches fell over much of the rest of the Raccoon River basin. A sharp rise occurred on the north Raccoon at Sac City with the river rising from just over 10 feet to nearly 16 feet in a little over 24 hours. Moderate to heavy rains of one to one and one quarter inch fell on the night of the 21st over portions of the South Skunk and Squaw Creek river basins north of Ames. This caused some sharp within-bank rises on these rivers, but no flood stages were reached. Rainfall on the night of the 22nd was much lighter, especially over areas which received heavy rain the night before. A few heavy showers fell over extreme southern Iowa, primarily over the Chariton and Grand River basins. Moderate within-bank rises were observed on these rivers as a result. Overall statewide precipitation for the month was 6.27 inches, nearly double the normal of 3.16 inches. This was a new record rainfall for the month of April in Iowa. Temperatures averaged 50.8 degrees, slightly above normal and the warmest April since 1991. This round of flooding was more serious than the round that occurred earlier in the month. There were several road closures from time to time, though no serious damage was reported. Much of the flooding was over agricultural lands. Though this was significant, personal property losses were not all that serious.