Advancements in Radar-Derived Hail Products for Estimating Hail Damage

Traditionally weather radar-estimated maximum hail size has been used as the primary, and often only, product to relate potentially damaging hailstorms to insurance claims. These estimates are commonly based upon a relationship to equivalent radar reflectivity. Past research has shown that while hail size alone does a decent job relating where damaging hail will occur, there is room for improvement. The Verisk hail algorithm is a fully polarimetric-based algorithm that yields estimates for both hail size and impact energy. Moving away from only maximum hail size in favor of hail impact energy results in a solution better suited to capture the true damage rates of a high impact storm. The combination of the hail size and impact energy yields a robust correlation to the spatial distribution of historical insurance claims data when compared to non-polarimetric hail size or hail kinetic energy products. The hail impact energy product is especially useful in the cumulative impact of hailstorms, providing a measure for damage incurred over time and not just instantaneous per event. Future improvements in the underlying representation of the distribution and characteristics of hail stones will act to further improve these estimates and capture a broader range of storm morphologies and characterizations.