Stochastic models of severe weather watches and warnings

To alert the public to the possibility of severe weather, the National Weather Service (NWS) issues severe weather watches and warnings. The NWS calculates three warning performance measures: probability of detection, false alarm rate, and average lead time. The NWS does not calculate watch performance measures. Community emergency managers use the NWS performance measures to design watch and warning response plans, but the performance measures do not provide information needed for rational decision making under uncertainty. Two stochastic models are formulated that quantify uncertainty in severe weather alarms: a one-stage alarm for those who respond to warnings, and a two-stage alarm for those who respond to watches and warnings. The models identify all possible sequences of watches, warnings, and events and characterize the sequences in terms of chains of transition probabilities and distribution functions of the watch and warning durations, lead times, areas, and the time to warning from a watch.