Oh hail! A climatological analysis of giant hail within the United States
Jessica M.Meyer1 and K.M.Wood1
1Department of Hydrology and Atmospheric Sciences
The University of Arizona, Tucson, AZ
The Vivian, South Dakota world record hailstone (8” in diameter) event in 2010 highlighted socioeconomic disparities associated with NEXRAD coverage gaps over rural areas and Indigenous lands, reducing safety and access to warnings for the protection of both life and property. In addition, hail storms have resulted in billion-dollar disasters every year since 2016, though giant hail reports decreased in the late 2010s and increased in more recent years. These events motivated a climatological analysis of giant hail (hail ≥4" in diameter) within the United States between 1975-2024, with emphasis on the latter 25-year period, using hail reports from the Storm Prediction Center’s Severe Weather Database. In this study, hail reports are evaluated across the contiguous United States as well as within multiple hail-prone regions to assess timing and frequency of these reports. Though improved detection during 2000-2024 likely has some effect on hail counts, our findings indicate a shift in the average time of day at which giant hail is observed, as well as shifts in seasonal distribution and seasonal peak that vary by region across hail sizes. On time scales shorter than 25 years, there is influence of teleconnections on hail activity, particularly from the Indian Ocean Dipole.