During mid-October 2005, a large monsoon-like system developed in the Caribbean Sea. A broad low pressure area formed on October 13 to the southeast of Jamaica, which slowly became more defined. On October 15, the National Hurricane Center (NHC) classified the system as Tropical Depression Twenty-Four while located about east-southeast of Grand Cayman. The depression drifted southwestward through a favorable environment, including warm sea surface temperatures. The depression strengthened into a tropical storm on October 17, whereupon the NHC named it "Wilma". Initial intensification was slow, due to Wilma's large size and a flat pressure gradient, although the associated convection gradually organized.