General Circulation Model Scenarios for the Southern United States

Abstract

The “Southern United States” extends roughly from 75° to 100° west longitude and from 30° to 37° north latitude (Figure 2.1). Elevations within the region range from near sea level along the Gulf and Atlantic coasts to more than 1800m in the Appalachian Mountains. The climate of locations within the southeastern United States is determined primarily by latitude, by proximity to the Gulf of Mexico and the Atlantic Ocean, and by altitude. Overall, the climate is temperate, becoming largely subtropical near the coast. Summers are long, hot, and humid, with little day-to-day temperature change. Late June to mid-August receive local afternoon thundershowers. The coldest months are December, January, and February, during which the region is subject to frequent shifts between exposure to moist, mild, Gulf air and cool, dry, continental air. Severely cold weather seldom occurs. Except at higher elevations, temperatures of - 17.8 °C or lower are rare and occur only when there is snow on the ground. The last spring freeze (T < - 2.2 °C) generally occurs between March 15 and April 15. The first fall freeze (T < -2.2 °C) generally occurs between October 15 and November 15 (Koss et al., 1988).