89th American Meteorological Society Annual Meeting

Monday, 12 January 2009: 5:00 PM
A climatological analysis associating spring tornadic activity with antecedent precipitation and drought in the Southeastern United States
Room 127BC (Phoenix Convention Center)
Marshall Shepherd, University of Georgia, Athens, GA; and D. Niyogi, T. L. Mote, and J. Entin
Using rain-gauge and satellite based rainfall climatologies and the NOAA Storm Prediction Center tornado database (1952-2007), this study found a statistically significant tendency for wet (dry) fall-winter seasons to be correlated with above (below) normal tornado days in the following spring season in North Georgia and other regions of the Southeast. Years with antecedent rainfall less than 85% of normal (e.g. “meteorological drought”) were most likely to be associated with below-normal tornado days and were only associated with above-normal tornado days 7% of the years. On average, non-drought years had nearly two times as many tornado days in the study area as drought years. Non-drought years were also five to six times more likely to have multiple tornado days (e.g. a day with > 1 reported tornado) than in drought years. Results were generally replicated for the modern Doppler radar era.

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