Hurricane Irene was a large and very destructive hurricane which affected much of the Caribbean and East Coast of the United States during the 2011 Atlantic hurricane season. The ninth named storm, first hurricane, and first major hurricane of the 2011 hurricane season, Irene originated from a well-defined Atlantic tropical wave that began showing signs of organization east of the Lesser Antilles. Due to development of atmospheric convection and a closed center of circulation, the system was designated as Tropical Storm Irene on August 20, 2011. After intensifying, Irene made landfall in St. Croix as a strong tropical storm later that day. Early on August 21, the storm made a second landfall in Puerto Rico. While crossing the island, Irene strengthened into a Category 1 hurricane. The storm paralleled offshore of Hispaniola, continued to slowly intensify in the process. Shortly before making four landfalls in the Bahamas, Irene peaked as a 120 mph (195 km/h) Category 3 hurricane.