The 2013 hurricane season was supposed to be terrible. The National Oceanic and Atmospheric Administration predicted between 13 and 20 named storms, up from 2012 when Isaac and Sandy hit the United States. But the season—which ends tomorrow—has been far more subdued than they thought. In fact, 2013′s hurricane season was the least active since 1982, and not a single hurricane made landfall in the United States.
The higher-than normal activity forecast by NOAA is based on three factors, all of which favor more, rather than fewer, tropical storms. The first is higher-than-normal sea-surface temperatures in the Atlantic, which supplies energy for tropical storms. The second is that hurricane activity has historically waxed and waned in cycles that last between 25 and 40 years. An active cycle began in 1995, which suggests we should expect more storms than average until 2020, at least. Finally, there’s no evidence of an El Nino event in the Pacific Ocean this summer; El Nino’s can strengthen upper-level winds across the tropical North Atlantic, which can tear hurricanes apart before they can gather strength.
But that didn’t happen. No hurricanes made landfall, and only two of the storms that formed in the Atlantic Basin became hurricanes. Andrew Freeman, also at Climate Central, explains why the predicted season didn’t happen:
Meteorologists have cited several reasons for suppressing Atlantic storms this year. Those inhibiting factors include an unusual abundance of dry, dusty air blowing off Africa’s Sahara Desert, an unusually stable atmosphere across the tropical North Atlantic, with broad regions of sinking air and above-average wind shear, which refers to winds blowing in different directions or at different speeds with height.
Of course, the rest of the world didn’t get off the hook quite as easily as we did. Super Typhoon Phailin hit India in September, and Super Typhoon Haiyan devastated the Philippines recently. But in the United States, the skies have been calmer than anybody predicted.
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