Preliminary Evaluation of SSCRAM-Based Severe Thunderstorm Forecasts
John Hart, NWS Storm Prediction Center, Norman, OK
Ariel Cohen, Storm Prediction Center
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Abstract
The Statistical Severe Convective Risk Assessment Model (SSCRAM; Hart and Cohen 2016) was developed using the SPC Mesoscale Analysis system to determine the short-term potential for severe storm reports in the path of observed thunderstorms.  This study uses the SSCRAM system to objectively quantify severe-thunderstorm probabilities based on the historical frequency of severe-storm occurrence given specific environmental conditions.  These relationships have been applied to various forecast-model output (e.g., RAP, NAM, and GFS) for several months since November 2016, providing an initial evaluation of the accuracy of these methods in forecasting severe storms.  The goal of this work is to eventually provide reliable probabilistic guidance for severe storm potential from the short-range through the medium-range (i.e., Days 3-8) forecast periods.