REGIONAL AND TEMPORAL VARIATIONS IN HEAVY PRECIPITATION IN SOUTH-CAROLINA

Daily precipitation amounts greater than 50 mm from long-term weather stations in South Carolina were analysed in order to determine their s easonal and annual frequencies and spatial variability. Year to year, the annual amount of precipitation produced by heavy rainfalls was not well correlated between stations (-0.10 less-than-or-equal-to r less- than-or-equal-to +0.65). The seasonal analysis detected three heavy pr ecipitation regimes: (i) the mountainous region in western South Carol ina with a winter maximum; (ii) the coastal plain with a distinct summ er maximum; and (iii) the region in between with a summer-autumn maxim um. Such results indicate that site-specific data should be used to ex amine large daily precipitation amounts rather than regionally average d data because the primary four climatic and synoptic controls that cr eate heavy precipitation vary considerably across South Carolina. Temp oral analyses of the site-specific, annual, large daily precipitation amounts and regional average annual precipitation showed generally wea k to moderate correlations (+0.25 less-than-or-equal-to r less-than-or -equal-to 0.57), indicating that interannual changes in annual precipi tation are not well related to changes in annual contributions due to large daily precipitation amounts. Differences between regional wet an d dry decadal periods were associated with significant changes in the annual large daily precipitation amounts at some but not all stations, indicating that similar long-term changes cannot be assumed across a region as small as South Carolina. This information is useful to water managers and has potential utility for estimating conditions in a cha nging climate.