Polarimetric Analysis of Two Giant-Hail-Producing Supercells Observed by X-Band and S-band Radars

Much remains unknown about the complex scattering characteristics of giant hail at common radar frequencies owing largely to the wide range of properties characterizing hail observed within supercells (e.g., varying hailstone density, ice temperature, and amount and distribution of liquid water on or within the hailstone). This study examines two storms that produced hail exceeding 12 cm in diameter in Oklahoma -- a supercell that produced the largest hailstone on record in Oklahoma (23 May 2011 near Gotebo, OK) and a supercell that produced large amounts of giant hail on 29 May 2012 near Kingfisher, OK -- using data collected by RaXPol (a mobile, high-resolution, rapid-scan, polarimetric X-band radar) and KOUN (an S-band WSR-88D radar). With the addition of nearly 350 observations of hailstone size collected by participants of the HailSTONE field project, the characteristics of small, large, and giant hail as observed at S and X bands are examined. Although the discriminating power of the commonly-used radar products in differentiating small, large, and giant hail is not particularly robust in these real-world observations, both supercells featured extremely prominent regions of low co-polar cross-correlation coefficient aloft preceding the observation of extremely large hail at the ground.