Say goodbye to the 2011 Atlantic hurricane season, which was a study in contradictions: It spared the usual Southern targets while Irene paralyzed the Eastern seaboard and devastated parts of the Northeast with deadly flooding. The season ended Wednesday as the sixth straight year without U.S. landfall of a major hurricane, yet Irene was one of the costliest storms in U.S. history and killed at least 47 people here and at least eight more in the Caribbean and Canada.