Subjective Probabilistic Tornado Forecasts: Some Experimental Results

Abstract

An experiment was conducted at the National Severe Storms Forecast Center during 1976 and 1977 in which National Weather Service forecasters formulated probabilistic forecasts of several tornado events in conjunction with both severe weather outlooks and severe thunderstorm and tornado watches. The results indicate that the probabilistic forecasts associated with the outlooks were quite reliable and exhibited positive skill, relative to forecasts based on sample climatological probabilities. The probabilistic forecasts associated with the watches, however, were less reliable and skillful. In view of the lack of prior experience at making probabilistic tornado forecasts, as well as the absence of feedback, comparable objective probabilistic guidance, and even appropriate past data on which to base climatological probabilities, the results of the experiment are quite encouraging. Some suggestions for further work in probabilistic tornado forecasting are provided.