A SYNOPTIC CLIMATOLOGY OF EXTREME UNSEASONABLE FLOODS IN THE SOUTHEASTERN UNITED STATES, 1950–1990 |
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| Authors: | Douglas W Gamble Vernon G Meentemeyer |
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| Institution: | 1. Department of Geosciences , Mississippi State University , Mississippi State, Mississippi 39762;2. Department of Geography , University of Georgia , Athens, Georgia 30602 |
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| Abstract: | Unseasonable floods are floods that occur in the season of lowest flood frequency, or dry season. Such floods pose a unique problem to flood planners and forecasters, yet little research has investigated the physical processes associated with unseasonable floods. The purpose of this study is to construct a synoptic climatology of extreme unseasonable floods for the southeastern United States. Results indicate that the types of storms creating unseasonable floods are location specific, with four unique regions across the study area: Carolina (tropical storms/hurricanes), Georgia Coastal Plain (Gulf depressions), Gulf-Atlantic (frontal), and Tennessee (frontal with upper-air enhancement). The precipitation created by these storms is low to moderate, rarely exceeding the 10-year 24-hour storm total. The precipitation levels suggest that a combination of meteorological conditions and land-surface conditions create the extreme events. A statistical analysis indicates that high soil-moisture levels combine with the moderate rains to produce extreme unseasonable floods. Key words: unseasonable floods, synoptic climatology, land-surface conditions, southeastern United States.] |
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