After record February snowfall in Iowa, the return of warmer weather and some significant rainfall in mid-March led to rapid snowmelt and breaking up of ice on rivers and streams, resulting in flooding in many parts of the western Midwest and catastrophic flooding in some areas.

The three winter months of December through February rank­­ed as the third wettest such period in 147 years in Iowa. For the contiguous United States, this three-month period was the wettest on record since...