Anthropogenic Climate Change Effects on Melting-Level Heights

Previous research using analyses of environmental parameters from climate models (e.g. CAPE, vertical wind shear) has drawn the common conclusion that the frequency and intensity of severe thunderstorms in the U.S. will increase. As research becomes more focused on changes to more specific severe thunderstorm hazards, changes in other environmental parameters becomes more relevant. One of these research areas involves changes in surface hailfall, where changes in the melting level height, influencing the depth over which falling hail may melt and reduce in size before reaching the ground is critically important.

Using output from three different CMIP5 models (NCAR-CCSM4, GFDL-CM3, MIROC5) run under the RCP8.5 scenario that has been used in past studies of possible convective weather frequency in the future, we will assess changes in the height of the melting level across the contiguous United States within these different climate projections. For comparison, output from the “historical simulations” from 1990-1999 over the summer months will be compared to that from the projections for 2070-2099.

Our results indicating any increases or decreases in melting level height will provide insight into possible changes in hail frequency or size at the ground and will be used along with future results from high-resolution simulations of hailstorms in these projected environments, to understand tendencies in the hailfall results.