Combining Probabilistic Ensemble Information from the Environment with Simulated Storm Attributes to Generate Calibrated Probabilities of Severe Weather Hazards

The Storm Prediction Center (SPC) has been generating probabilistic forecasts of severe weather hazards (i.e., tornado, wind, and hail) for a number of years; however, there is a lack of calibrated probabilistic guidance available to the SPC forecasters. One approach recently developed to create calibrated hazard probabilities involves combining environment information (e.g., CAPE and shear) from the Short-Range Ensemble Forecast (SREF) system with explicit storm-attribute information (e.g., updraft helicity) from the SPC Storm-Scale Ensemble of Opportunity (SSEO). A description of the method used to extract fields and generate calibrated probabilities for each hazard will be presented. In addition, subjective and objective results from the 2014 Hazardous Weather Testbed Spring Forecasting Experiment will be shown along with examples from several severe-weather cases during the past year.