WSR-88D Observations of an Extreme Hail Event Impacting Abilene, TX on 12 June 2014

On 12 June 2014, an intense supercell thunderstorm with hail to at least 12 cm in diameter impacted Abilene, Texas, during the Children's Art and Literacy festival and parade, resulting in several minor injuries. The storm produced widespread damage to vehicles, homes, and businesses, costing an estimated 400 million dollars. More than 200 city vehicles sustained significant damage, with Abilene Fire Station #4 rendered uninhabitable. The National Severe Storms Laboratory's Severe Hazards Analysis and Verification Experiment (SHAVE) collected an impressive data set on this event, including 30 observations of hail >5 cm and 16 observations of hail 18–44 mm in diameter. An additional 45 observations of hail >25 mm were obtained by the San Angelo, TX NWS as part of its warning verification effort.

The storm occurred within 100 km of the KDYX WSR-88D (located at Dyess AFB). This study examined the character and evolution of the Abilene hailstorm from 2100–2359 UTC, as seen by KDYX. Overall storm intensity was assessed via several reflectivity and velocity derived parameters: maximum reflectivity at the 253K height (Z_253K), vertically-integrated liquid (VIL), maximum expected size of hail (MESH), storm-top divergence (STD), and mid-altitude rotational velocity (MRV). The MESH did an excellent job at predicting the hail threat via a peak value of 113 mm around an hour prior to several softball-size (114 mm) hail observations. The STD briefly exceeded 100 m s^-1 (maximum STD of 102 m s^-1) within several minutes of the softball-size hail observations, with the MRV occasionally exceeding 30 m s^-1 between 20–40 min prior to the maximum in STD.

The extensive data set of hail observations were used to generate scatter-plots of hail size versus low-altitude measures of several dual-polarization parameters: horizontal reflectivity (Z_H), differential reflectivity (Z_DR), cross-correlation coefficient (ρ_HV), and specific differential phase (K_DP) . The results show most of the large hail was associated with high Z_H (≥54 dBZ), low Z_DR (<1 dB), and a fairly wide range of ρ_HV (0.85–1.00) and K_DP (0–5° km^-1).