2013 ATLANTIC BASIN HURRICANE SEASON June 1 – December 30. REASONS FOR A SLOWLY DEVELOPING SEASON. "A large area of high pressure over the central Atlantic has been very strong and very good at driving dry air southward into the tropics into September. Generally it is easier for tropical storms to form and tropical storms to streng-then into hurricanes when an un-obstructed supply of moisture available Tropical Storm Karen ---Elventh Storm Of 2013 Season. Expected to be a rainmaker in the USA. Presentation courtesy of Dr Walter Hays, Global Alliance for Disaster Reduction