An overview of SPC severe outlook and watch verification

A key mission of the Storm Prediction Center (SPC) is the forecasting of severe thunderstorms over the continental United States. Given the high-impact nature of tornadoes, large hail, and damaging wind, it is crucial for the forecast performance of such forecasts to continually be analyzed. If a major severe weather event is forecast, how often does it occur? If a major severe weather event occurs, how often has it been forecast in advance?

This study will present an overview of SPC severe outlook and watch verification for the period 2003-2010. Particular emphasis will be placed on the performance of high-impact forecasts, such as Tornado Watches and “High Risk” outlooks, and the detection of high-impact events, particularly with respect to tornadoes. Along with traditional verification measures, which are strictly based on severe weather reports, forecast performance with respect to coverage of severe weather warnings will also be presented, as a way of linking SPC forecast products to the likelihood of people in risk areas being asked to take action to protect life and property.