Aaron W. Johnson, Kelly E. Sugden<\/em><\/p>\n Severe-convective hailstorms are one of the most frequent weather hazards across the United States.\u00a0 However, studies evaluating the ability of various environmental indices to differentiate lower-end severe hail (\u22641.25 in, 32 mm) from significant hail (\u22652.0 in, 51 mm) prior to storm formation are limited and typically overlap very little with microphysically based research. To bridge this gap, this study builds a database of 520 hail reports that sort into one of four hail-diameter ranges. For each report, various thermodynamic and wind-related fields are then extracted from Rapid Update Cycle (RUC) model analysis to create a parameter-based hail climatology.<\/p>\n Analysis of these environmental indices indicates most wind-based parameters display weaker magnitude winds and resultant shear for the smallest hail-size bin compared to the three largest. Further, the three largest hail diameter bins reveal nearly identical parameter values in the lowest 6 km AGL.\u00a0 In contrast, non-traditional shear layers that include winds in the upper portions of a storm (>6 km AGL) display some skill to differentiate larger hail sizes, especially for \u22653.5-in (89-mm) hail. Thermodynamic variables produced mixed results, with variables such as CAPE displaying a slight tendency to increase as binned hail size becomes larger but still with significant overlap.\u00a0 On the other hand, non-traditional parameters such as the hail-growth-zone thickness reveal a relationship toward decreased depth as the binned hail size increases, but with little to no increase in hail-growth-zone CAPE. Finally, evaluation of the significant severe parameter (SSP) and a new index called the large hail parameter (LHP) display mixed results.\u00a0 Skill at delineating \u22641.25-in (32-mm) report from 2.0-3.25-in (51-83-mm) cases for LHP (SSP) is slightly better (worse) than 0-6-km AGL bulk vector shear. However, the LHP displays improved skill over any other parameter to differentiate \u22653.5-in (89 mm) reports from those with less than 2.0-in (51-mm) diameter hail. The LHP formula creates improved skill by including non-traditional environmental parameters typically associated with storm longevity, precipitation efficiency, and hail-growth rates.<\/p>\nAbstract<\/h4>\n