Climatology of tropical cyclone rainfall in the Southeastern United States

Rainfall associated with tropical cyclones contributes a significant amount to the annual rainfall in the southeastern United States. This study quantifies this amount from 1980–2004 as we compare the total rainfall to an amount excluding rainfall arising from tropical cyclones. Additionally, we use these precipitation amounts to examine the climatic water balance and observed hurricane season moisture deficits and compare actual deficits to deficits with tropical cyclone rainfall removed. Tropical cyclones contribute as much as 15% of the hurricane season rainfall along portions of the Carolinas. The Appalachian Mountains act as a barrier to the inland influence of tropical cyclone rainfall and generate a spatial rainfall gradient on mean precipitation maps. Within a hurricane season, the percentage of rainfall that can be attributed to tropical cyclones tends to progress eastward throughout the season. Temporally, rainfall from tropical cyclones has increased over much of the region, while non-tropical cyclone rainfall has largely remained unchanged. With respect to the water

balance, soil moisture deficits would significantly increase if the southeastern United States did not receive rainfall from tropical cyclones. This would have consequences for the agricultural community and would increase the reliance on irrigation in agricultural

production.