Handout (2.2 MB)
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 (Z253K), 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 (ZH), differential reflectivity (ZDR), cross-correlation coefficient (ρHV), and specific differential phase (KDP) . The results show most of the large hail was associated with high ZH (≥54 dBZ), low ZDR (<1 dB), and a fairly wide range of ρHV (0.85–1.00) and KDP (0–5° km-1).
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