Daryl Herzmann – Mentor Department of Agronomy, Iowa State University


Tornado warning lead time is the amount of time between the issuance of a tornado warning and an actual tornado report. Tornado warning lead times have been declining recently, even though there have been significant changes in forecasting during this time. The goal of this research was to see if lengthening tornado warning lead times to greater than 30 minutes is plausible. To accomplish this research, both cases of verified and unverified tornado warnings were analyzed. Each verified tornado warning was designated a storm type, (supercell, quasi-linear convective system and unknown). Next, radar analysis of verified tornado warnings was used to determine if a tornado will be verified based upon its forecasted development. Along with examining verified tornado warnings, cases of 30-minute tornado warning durations without a verified tornado were studied to determine if the decrease of those reports showed a trend in lengthening lead times leading to more verified tornadoes. After the analysis of both verified and unverified tornado warnings, our research found that 30-minute or longer lead times work the best with supercells. However, the same conclusion could not be said from the other storm types. Also, our research concluded that there is not enough confidence to validate that the number of unverified tornado warnings will decrease in the future. Therefore, lengthening tornado warning lead times to at least 30 minutes is a mere suggestion at this point.

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Matthew D. Gunn

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