Reconciling droughts and landfalling tropical cyclones in the Southeastern United States

Abstract

A popular perception is that landfalling tropi- cal cyclones help to mitigate droughts in the Southeast- ern United States (SeUS). However intriguing paradigms on the role of large scale SST variations on continental US including SeUS droughts and seasonal Atlantic tropi- cal cyclone activity confronts us. These paradigms suggest that in the presence of warm (cold) eastern tropical Pacific and cold (warm) Atlantic Ocean sea surface temperature anomaly (SSTA) lead to the increased likelihood of wet- ter (drier) conditions over the continental US including the SeUS. Juxtaposing this understanding with the fact that landfalling tropical cyclones contribute significantly to the annual mean total rainfall in the SeUS and in El Nino (La Nina) years with cold (warm) tropical Atlantic SSTA lead to reduced (increased) Atlantic tropical cyclone activity raises a conflict on the role of the large-scale SST varia - tions in SeUS hydroclimate. This study attempts to inves- tigate the apparent dichotomous role of the large scale SST variations on the SeUS hydrology by examining the role of rainfall from landfalling tropical cyclones in the SeUS to local seasonal droughts. Our study finds that the contribu - tion of the rainfall from landfalling tropical cyclone on the mitigation of monthly drought in the 28 SeUS watersheds