Scaling Analysis of Rainfall over the Driftless Area of the Midwest

The Driftless Area of southeast Minnesota, southwest Wisconsin, northwest Illinois, and northeast Iowa has been plagued by record breaking floods in the past decade including both flash floods and multi-day events. Improving flood forecasting in the Driftless Area is of particular interest to the North Central River Forecast Center (NCRFC). In this study, the spatial and temporal scaling behavior of rainfall over the Driftless Area is explored to provide better understanding of the storms responsible for the quick response flood events in this region. Particular focus will be placed on summer convective rainfall over the Kickapoo River basin of southwest Wisconsin. A cascade-based approach was used to characterize the multi-scale statistical behavior of the rainfall. Trends in scaling parameters with storm type, storm movement and development, time scales of flood response and terrain were tested. Scaling behavior between verified flash flood warned storms and false-alarm events were compared for storms that elicited flash flood warnings.