Hurricane Irene 2011, Atlantic, Caribbean

On August 15, 2011, a tropical wave exited the African coast and emerged into the Atlantic, characterized by distinct low-level cyclonic rotation and deep tropical humidity. It remained well-defined while moving steadily westward for several days through the Cape Verde Islands, although at the time any notable convection occurred well to the southwest of its axis. As the wave distanced itself from the islands, development of thunderstorms and showers in its proximity continued to remain scarce, and it became rather broad in appearance. On August 19, the convective structure began to show signs of organization as the associated atmospheric pressure lowered, and with a progressively favorable environment situated ahead of the wave its chances of undergoing tropical cyclogenesis markedly increased. The strong thunderstorm activity continued to become more pronounced around the main low-pressure feature. By August 20, the National Hurricane Center (NHC) noted that tropical cyclone formation was imminent as the wave neared the Lesser Antilles, and a reconnaissance aircraft confirmed the presence of a small surface circulation center just southwest of a burst of vigorous convection and unusually high sustained winds, indicating sufficient organization for the cyclone to be upgraded into Tropical Storm Irene at 23:00 UTC that day.
Irene was positioned about 190 mi (305 km) east of Dominica in the Lesser Antilles when it was classified and named, along weakening high pressure over the west-central Atlantic, inducing a roughly west-northwestward path for most of its journey through the eastern Caribbean. Its mid-level circulation continued to become better established as hints of pronounced banding features curved north of the surface center. On August 21, the surface center reformed closer to the deepest convection; furthermore, an anticyclone aloft provided supportive outflow over the cyclone. With the improved structure, as well as light wind shear and high sea surface temperatures, Irene was forecast to strengthen to near hurricane force prior to landfall in Hispaniola. Over the subsequent day (August 22), while passing near the island of Saint Croix in the U.S. Virgin Islands, Irene traced toward Puerto Rico, more northward than initially expected, where it underwent a considerable increase in strength and organization. Hours later, Irene moved ashore, approaching from the southeast at landfall near Punta Santiago, Humacao, Puerto Rico, with estimated sustained winds of 70 mph (110 km/h). Despite the storm's interaction with land, radar imagery showed a ragged eye-like feature, and Doppler radar data indicated wind speeds in excess of hurricane force. Just after its initial landfall, Irene was accordingly upgraded to a Category 1 hurricane, the first of the 2011 Atlantic hurricane season.
With the hurricane then situated just north of the mountainous coast of Hispaniola, the storm deepened little after reemerging over water, and any additional organization during the rest of the day was gradual. After briefly weakening on August 23, however, Irene began to develop a distinct eye encircled by an area of deepening convection the next morning. Moving erratically through the southeast Bahamas over very warm waters, Irene quickly expanded as its outflow aloft became very well established; the cyclone intensified into a Category 3 major hurricane as it recurved toward the northwest along a weakness in the subtropical ridge. The cyclone subsequently underwent a partial eyewall replacement cycle, which resulted in some reduction in its winds. Although a distinct eye redeveloped for a few hours, it obscured once again soon thereafter; Irene was unable to recover from the cycle, with no further significant intensification expected henceforth.
Early on August 27, Irene further weakened to a Category 1 hurricane as it approached the Outer Banks of North Carolina. At 7:30 am EDT (11:30 UTC) the same day, Irene made landfall near Cape Lookout, on North Carolina's Outer Banks, with winds of 85 mph (140 km/h). After having tracked over land for about 10 hours, the eye of Irene became cloud-filled, although the center remained well-defined on radar images. Later on August 27, Irene re-emerged into the Atlantic near the southern end of the Chesapeake Bay in Virginia. Shortly before sunrise, at about 09:35 UTC on August 28, Irene made a second landfall at the Little Egg Inlet on the New Jersey shore, and soon after moved over water again. Hours later, Irene weakened to a tropical storm just as it made a third U.S. landfall in the Coney Island area of Brooklyn, in New York City, New York, about 9:00 am EDT (13:00 UTC) on August 28.