Changes in future flood-producing storms in the U.S.

Erin Dougherty

Colorado State University

Friday, Nov 15, 2019, 1:00 pm
DSRC Room 1D403

Abstract

Floods in the continental United States (CONUS) cause tremendous damage, accounting for over $123.5 billion in adjusted losses from 1980–2018. While floods in the current climate are already destructive, flood risk is projected to increase in the future based on work using global climate models. However, global climate models struggle to resolve precipitation structure, intensity, and duration, which motivates the use of convection-permitting climate models that more accurately depict these precipitation processes on a regional scale. These high-resolution convection-permitting simulations have been used to examine future changes to rainfall, but not specifically in a large number of floods. This study fills this gap by examining future changes to nearly 600 flash flood-producing storms over the U.S. using convection-permitting models under a pseudo-global warming framework. Rainfall characteristics and runoff in these flash flood-producing storms are examined in a future, warmer climate to understand the bulk sense of how these storms might change. Regional analyses are then conducted over California and the Mississippi River Valley–two flood hotspots in the CONUS–to understand the specific regional impacts of projected future changes to flood-producing storms. In California, which experiences both flash and slow-rise flood-producing storms mainly due to land-falling atmospheric rivers, changes to precipitation, runoff, and environmental conditions are explored. In the Mississippi River Valley, changes to flash flood-producing storms are examined by the strength of these primarily convective storms. Though regional impacts differ, floods intensify in a future warmer climate, suggesting cities over the CONUS need to prepare for this in order to create more resilient communities.