Tropical cyclones and drought amelioration in the gulf and southeastern coastal United States

Abstract

Precipitation from land-falling tropical cyclones (TCs) has a significant hydroclimatic influence in the southeastern United States, particularly during drought years. The frequency with which TCs ended drought conditions was examined for southeastern coastal states from Texas to North Carolina during 1895-2011. The region was divided into the Gulf Coast states (GCS) and the southeastern Atlantic coast states (ACS). The spatiotemporal patterns of tropical cyclone drought busters (TCDBs) were analyzed. Larger-scale ocean- atmosphere influences on TCDBs were examined using chi-squared analysis. The ACS experienced TCDBs more frequently and farther inland compared to the GCS. The number of TCDBs has significantly increased with time in the ACS. TCDBs numbers in the GCS did not exhibit significant increases, but the area alleviated of drought conditions increased significantly in the last 117 years. The dominant larger-scale ocean-atmosphere forcing of TCDBswas a combination of awarmAtlantic Ocean [positiveAtlanticmultidecadal oscillation index (AMO+)] and weak westerlies [negative North Atlantic Oscillation index (NAO-)]. AMO+ leads to an increase in the number of TCs throughout the North Atlantic basin, and NAO- increases the likelihood of TC landfall by controlling the steering of TCs toward the southeastern United States. © 2013 American Meteorological Society.