Hail Forecasting Parameters

This image depicts three forecasting parameters used to predict hail. They are CAPE in the layer from -10 C to -30 C, 0-6-km shear vector, and the freezing level height. Large CAPE in the layer from -10 C to -30 C favors rapid hail growth. 0-6-km shear in excess of 30-40 knots supports supercells with persistent updrafts that contribute to large hail production. Finally, lower freezing level heights suggest a greater probability of hail reaching the surface prior to melting, though melting impacts small hail much more than very large hailstones.