PNNL

Abstract

While extreme precipitation is expected to increase in a warming climate, its scaling with temperature at weather timescales often produces puzzling results. Here, we focus on the summer months over the central U.S. to investigate the scaling of extreme precipitation intensity (EPI) with local temperature and determine the contribution of mesoscale convective systems (MCSs) to the EPI scaling. Using an observational dataset that differentiates precipitation associated with MCS and non-MCS storms, we find that MCS storms contribute to 70% of EPI samples at temperatures lower than 298K where EPI increases with temperature. However, at temperatures higher than 298K, MCSs’ contribution to EPI decreases as the predominant storm type shifts from MCS to non-MCS storms, causing EPI to decrease with temperature due to the weaker rainfall intensity associated with non-MCS storms compared with MCS storms. Our findings underscore the important role of different storm types in affecting the EPI scaling relationships.