Putting the Record Breaking May 8th Denver Hail Storm into Historical Context

On the afternoon of May 8, 2017, a storm complex developed in upslope flow over the high terrain of Jefferson County, Colorado and intensified as it descended into the Denver metropolitan area. At its peak, the storm produce up to baseball sized hail just northwest of downtown and a swath of severe hail extending up to 8 miles wide. According to the Rocky Mountain Insurance Institute, the storm caused at least $1.4 billion worth of insured losses and is considered the costliest natural disaster in Colorado history. Moreover, this storm is also unique in that at least half the insured losses are estimated to have been inflicted on automobiles, with a projected 150,000 auto claims.

This study will examine the meteorological conditions and radar signatures associated with this storm. Of particular interest is the development of a deep convergence zone corresponding to the period when the largest hail fell. Additionally, the storm will be placed in historical context using CoreLogic’s forensic hail algorithm by estimating the areal coverage of eight of the twelve costliest storms in Colorado history. Finally, the hail swaths will be cross-referenced with CoreLogic’s unique residential property database to provide unquie insights into the societal impacts.