PNNL

Abstract

Hailstones and extreme precipitation generate substantial economic losses across the United States (US) and the globe. Their strong association with short-lived, intense convective storms poses a great challenge to predict their future changes. Here we conducted model simulations at 1.2 km grid spacing for severe convective storms that produced large hail and heavy precipitation and occurred in two typical types of synoptic-scale environments in spring seasons over the central US under both current and future climate conditions. We find that the responses of large hail and heavy precipitation to anthropogenic climate change (ACC) are markedly different between the two types of synoptic-scale environments. The storms in the frontal systems are sensitive to the ACC, with over 80% increase in large hail (diameters > 2.5 cm) occurrences and over 45% increase in heavy precipitation occurrences, whereas the storms in the Great Plains low-level jet (GPLLJ) environment have weak responses with less than 10% increase in large hail occurrences and less than 15% in heavy precipitation occurrences. These differences are explained by the larger increase in convective intensity and updraft width and a smaller increase in warm cloud depth in the frontal storms compared with the GPLLJ storms. These results have important implications for predicting and managing risks for future hail and flash floods.