The 2007 Atlantic basin hurricane season ends today. For the second year in a row there were fewer named storms than predicted.
In the end, the 2007 hurricane season yielded six hurricanes, two major hurricanes and 14 named storms, one of which was sub-tropical storm Andrea. The six hurricanes and two major hurricanes are the norm for the Atlantic basin. The norm for named storms is 11.
Both of the season’s major hurricanes – Dean and Felix – reached Category 5 strength and passed through the western Caribbean Sea. Three days out, Hurricane Dean was forecast to cross Grand Cayman, causing the government and residents to fully prepare for the worst. More than 7,000 tourists and residents were evacuated as Dean approached, and more than 2,200 people went to hurricane shelters on the evening of August 19th.
Fortunately for Cayman, a high pressure system kept Dean from gaining latitude and the storm passed just more than 100 miles south of Grand Cayman, causing only minimal storm surge and wave damage.
Forecasters had predicted a more active season. The U.S. National Oceanic and Atmospheric Administration’s National Hurricane Center predicted 13 to 17 named storms; seven to 10 hurricanes; and three to five major hurricanes of Category 3 or higher.
The Colorado State University team of Philip Klotzbach and William Gray predicted 17 named storms, nine hurricanes and five major hurricanes.
The U.K.-based Tropical Storm Risk forecast 16.1 named storms plus or minus 3.8; 8.9 hurricanes plus or minus 2.6; and four major hurricanes, plus or minus 1.5.
There are several theories as to why the season was not as active as predicted. Gary Bell, a forecaster at NOAA cited weaker-than-expected effects of La Nina, a cooling of the sea surface temperatures in Pacific Ocean which normally increase Atlantic basis hurricane activity.
Cooler-than-normal sea surface temperatures in the tropical Atlantic, where many tropical storms are spawned, has also been cited a factor which contributed to less-than-expected hurricane season activity, as was higher wind sheer in the upper atmosphere.
Cayman’s Chief Meteorologist John Tibbetts said the month of November and the tail end of the hurricane season represents a transition month for weather here.
‘In the summer, we normally get our weather systems, things like hurricanes, tropical storms and depressions, from the east,’ he said. ‘In the winter, we look for our weather from the north.’
As a result, the Cayman Islands typically experiences cooler temperatures and less rain in the winter, Mr. Tibbetts said.
‘But we also experience stronger winds, more from the north and easterly.’