Hailfall in a Possible Future Climate Using a Pseudo-Global Warming Approach: Hail Characteristics and Mesoscale Influences.

Severe convective storms (SCS) and their associated hazards present significant societal risk. Understanding of how these hazards, such as hailfall, may change due to anthropogenic climate change is in its infancy. Previous methods used to investigate possible changes in SCS and their hail used climate model output and were limited by their coarse spatiotemporal resolution and less detailed representations of hail. This study instead uses an event-level pseudo-global warming (PGW) approach to simulate seven different hailstorms in their historical environments, and again in five different end-of-century PGW environments obtained from the worst-case scenario increases in CO₂ of five different CMIP5 members. Changes in large-scale environmental parameters were generally found to be consistent with prior studies, showing mostly increases in CAPE, CIN, and precipitable water, with minor changes in vertical wind shear. Nearly all simulated events had moderately stronger updrafts in the PGW environments. Only cold-season events showed an increase in hail sizes both within the storms and at the surface, whereas warm-season events exhibited a decrease in hail sizes at the surface and aloft. Changes in the event-total hailfall area at the ground also showed a seasonal trend, with increases in cold-season events and decreases in warm-season events. Melting depths increased for all PGW environments, and these increases likely contributed to greater rainfall area for warm-season events, where an increase in smaller hail aloft would be more prone to melting. The differences in PGW simulation hail sizes in cold-season and warm-season events found here are likely related to differences in microphysical processes and warrant future study. [ABSTRACT FROM AUTHOR]