New Hail Diagnostic Parameters Dervied by Integrating Multiple Radars and Multiple Sensors

There have been numerous National Weather Service (NWS) local and national studies comparing the relationship between various conventional radar- and environmentally-derived parameters for severe hail diagnosis in storms. A variety of different parameters have been used, including Vertically Integrated Liquid (VIL), VIL Density, Hail Diagnosis Algorithm (HDA) parameters, and other manually-derived parameters relating storm echo levels to environmental thermodynamic information.

Most of these parameters are derived from single radar Weather Surveillance Radar – 1988 Doppler (WSR-88D) Open Radar Products Generator (ORPG) products, either from gridded fields or from cell-based attributes from the Storm Cell Identification and Tracking (SCIT) algorithm.

The ORPG is limited in that it cannot integrate data from multiple-radars or multiple-sensors - in this case, Near-Storm Environment (NSE) data from mesoscale numerical models (e.g., RUC20). Therefore, any of these parameters which require environmental thermodynamic information must be determined by mentally integrating radar data with the NSE data – sometimes difficult to do for all storms for each volume scan. Also, when storms are under-sampled by a single radar (e.g., cones-of-silence, far ranges), attributes that are derived by vertically-integrating reflectivity (e.g., VIL) typically do not represent the true values in the storms, and in many cases are underestimated.

The National Severe Storms Laboratory (NSSL) Warning Decision Support System – Integrated Information (WDSSII) provided a development environment to integrate data from multiple-radars and multiple-sensors to rapidly prototype some new applications to diagnose hail in storms, including all of the parameters in the above list. The following manuscript will detail the status and progress of this work done collaboratively between the NWS Meteorological Development Laboratory (MDL) and NSSL.