Shift Toward Intense and Widespread Precipitation Events Over the United States by Mid-21st Century

The United States has witnessed an increase in the frequency of intense and spatially widespread precipitation events in recent decades. Using a high-resolution hybrid ensemble of regional climate simulations, we project further intensification of widespread extremes in the near future. The simulations cover 1966–2005 in the historical period and 2011–2050 in the future period under RCP8.5 scenario and show good correspondence with the observations in the historical period. The projected changes in the characteristics of precipitation events are associated with more frequent occurrence of extreme years where contribution from intense and widespread events to the annual precipitation is unprecedently high. While our findings are consistent with recent trends in the observations, they are in contrast to some earlier studies that project shrinking of precipitation events in the future period, which highlight the need for more rigorous investigations of changes in the spatial extent of precipitation in future climates.