Delaware: Floods and Droughts
By G.N. Paulachok and R.H. Simmons, U.S. Geological Survey; "General Climatology" section by J.R. Mather and J.A. Skindlov, Office of the State Climatologist of Delaware; "Water Management" section by L.A. Sprague and P.J. Cherry, Delaware Department of Natural Resources and Environmental Control
Excerpt from Introduction
Precipitation is the source of all freshwater in Delaware and results from movement of moist airmasses over the region, ascent and cooling of the airmasses, formation of clouds, and condensation of water vapor. The climate of Delaware is affected chiefly by airmasses of tropical maritime and polar continental origin. Meteorological extremes are moderated by nearby large water bodies. Depending on location, average annual precipitation ranges from about 41 to 46 inches. Extensive flooding, although infrequent, generally is caused by tropical cyclones such as hurricanes or tropical storms, whereas local flooding results from intense convective rainfall. Droughts occur when the Bermuda High, the principal moisture-delivery system for the State, is displaced from an oceanic to a stable continental position.
