Subjective tornado probability forecasts in severe weather watches

An experiment was conducted at the Storm Prediction Center (SPC) to assess the accuracy of subjective probability forecasts for tornadoes within indiv idual convective watch areas. Probability forecasts for one or more and thr ee or more tornadoes were produced for 166 severe weather watches during 19 97 and 1998. Categorical forecasts of maximum tornado intensity, as indicat ed by F-scale damage ratings, were also performed. The probability and inte nsity forecasts were made in an operational setting prior to the issuance o f each watch to simulate the decision making process that might be employed if the SPC were to begin including probabilities in their watch products. Results indicate considerable skill in forecasting tornado probabilities, t hough the maximum intensity Forecasts were not particularly accurate. It is hypothesized that accurate tornado intensity forecasts will be difficult t o achieve until storm-scale processes are more fully understood.