Climatology of flood-producing storms and their associated rainfall characteristics in the United States

Abstract

Floods are one of the deadliest weather-related natural disasters in the continental United States (CONUS). Given that rainfall intensity and the amount of CONUS population exposed to floods is expected to increase in the future, it is critical to understand flood characteristics across the CONUS. Therefore, the purpose of this study is to develop a flood-producing storm climatology over the CONUS from 2002 to 2013 to better understand rainfall characteristics of these storms and spatiotemporal differences across the country. Flood reports from the NCEI Storm Events Database are grouped by causative meteorological event and are merged with a database of stream-gauge-indicated floods to provide a robust indication of significant hydrologic events with a meteorological linkage. High-resolution Stage IV rainfall data were matched to 5559 flood episodes across the CONUS to identify rainfall characteristics of flood-producing storms in a variety of environments. This storm climatology indicates that flash flood–producing storms frequently occur with high rainfall accumulations in the summer east of the Rockies. Slow-rise flood-producing storms frequently occur in the spring–early summer (winter), with high rainfall accumulations over the northern and central CONUS (Pacific Northwest) due to rain-on-snowmelt, synoptic systems, and mesoscale convective systems (atmospheric rivers). Hybrid flood-producing storms, sharing characteristics of flash and slow-rise floods, frequently occur in spring–summer and have high rainfall accumulations in the central CONUS, Northeast, and mid-Atlantic. Results from this climatology may provide useful for emergency managers, city planners, and policy makers seeking efforts to protect their communities against risks associated with flood-producing storms.