Jonathan Labriola-February 17

Microphysical Treatment of Hail in High-Resolution Supercell Simulations

Hail causes over $1.0 billion in damage annually in the United States, despite this explicit hail prediction remains a relatively understudied subject.  This study compares high-resolution (500 m horizontal grid spacing) hail simulations for a severe hail event that impacted central Oklahoma on 19 May 2013.  Simulations are produced using the Milbrandt and Yau double moment (MY2), triple moment (MY3) and the NSSL double moment (NSSL) microphysics schemes. Microphysical budgeting terms, predicted hail size distributions, and simulated polarimetric signatures are analyzed to understand biases in predicted surface hail size and spatial extent.  Results indicate a prognostic particle size distribution (PSD) shape parameter improves representation of hail within the melting layer, reducing hail size over prediction biases.  Additionally, variable density rimed ice categories improve conversion rates between hydrometeor species making hail PSDs more realistic.