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NWS Tornado Warning History

[Graph shows a marked improvement in tornado detection probability and a decline in the false alarm rate over the time period 1986-2002]

New techniques for evaluating forecasts are also being studied. Using an approach based on signal detection theory to look at tornado warning performance, we can see periods of time when performance was relatively consistent. Changes occur associated with the deployment of the NWS WSR-88D radars, and with the development of tornado warning guidance based on results of the VORTEX project.