Simulations of exteme convective storms in future climates: proof-of-concept tests with a retrospective event

Global climate models (GCM) consistently project future anthropogenic climate changes in the frequency of extreme precipitation, particularly over North America. Not yet established, however, is how the projected changes in extreme precipitation will be manifest in locally intense rainfall and flash flooding over several-hour periods.

The precipitating weather systems that generate such sub-daily scale rainfall extremes typically are convective in nature and also are capable of producing destructive surface winds, hail, and tornadoes. Along with flash flooding, these hazardous weather phenomena tend to have significant impacts, yet their associated convective precipitating systems remain unresolved in typical global and regional climate models used to address global climate change.

Preliminary results will be presented of explicit simulations of sub-daily extreme rainfall events and their associated convective precipitating systems. In this study, a telescoping modeling approach is employed that culminates in 3D cloud-resolving model (CRM) integrations. Historical simulations, in which the Weather Research and Forecasting (WRF) model is forced with NCAR/NCEP reanalysis data, are used to depict the telescoping modeling approach accuracy. Initial simulations forced with GCM and intermediate regional climate model output under the IPCC SRES A2 emissions scenario will also be presented.

The ultimate goal of this project is to obtain projections of the characteristics, frequency, and geographical distribution of sub-daily extreme rainfall events per future greenhouse gas emissions scenario, and then to use this information to obtain projections of where and when the extreme rainfall will be accompanied by other hazardous weather phenomena.