Hurricane Season Slides By - And the U.S. Dodges the Bullet ~
It could have been a record year for hurricane damages. The storms were definitely there: almost exactly as predicted, the Atlantic basin gave rise to 19 named storms, including 12 hurricanes. But instead, this year's hurricane season set a different record: It was the fifth year in a row with no major hurricane making landfall on the United States. The last time that happened was more than a century ago. That's all the more remarkable given the number and intensity of Atlantic storms. This year's activity was double the usual rate - or, to be more precise, says Dr. Jeff Masters (" Hurricane season draws to a close"): "The 19 named storms, 12 hurricanes, and 5 intense hurricanes were 198%, 203%, and 217% of the 1950-2000 average for named storms, hurricanes and major hurricanes, respectively." Large-scale weather patterns - or as Masters puts it, "friendly steering currents" - held the storms off shore: "The reason the U.S. got so lucky--and that Canada and Mexico took a much more severe beating than usual--was that the Azores/Bermuda high was farther east than usual, and there were more strong troughs of low pressure over the U.S. East Coast than usual. In addition, there was stronger high pressure than usual over the U.S. Gulf Coast, which deflected Caribbean storms into Mexico." Rainfall records from this year's Atlantic tropical storms and hurricanes are shown in this graphic from NASA's Earth Observatory. On the other hand, the season was marked by a number of records and oddities that set this year apart for its intensity, not its mildness. In one rarity, three hurricanes - Karl, Igor, and Julia - occurred simultaneously in Mid-September. Julia was the easternmost hurricane ever reported; Karl, the farthest south ever to occur in the Gulf of Mexico. Hurricane Earl, as it passed near North Carolina with 140 mph winds in early September, was the fourth strongest Atlantic hurricane that far north. Hurricane Paula, which flared up off the coast of Honduras on October 11 and petered out over Cuba on October 15, set a record for rapid intensification. And then there's Hurricane Igor, the most damaging storm ever to strike Newfoundland, Canada. The reason for the powerful storm season is fairly simple: the water was hot. Professor Mark Saunders of Tropical Storm Risk (TSR) told a Tokyo audience, “The very active Atlantic hurricane season was caused primarily by record-breaking warm sea surface temperature anomalies in the tropical North Atlantic, combined with weaker than normal vertical wind shear caused by La Nin~a.” The speech is covered in a TSR summary (“ Remarkable 2010 Hurricane and Typhoon Seasons”). But the strong season was no global phenomenon. This year's Pacific typhoon season, in fact, was the opposite: one of the least active seasons in recorded weather history dating back to the 1960s, Saunders reported.
