By Steve Thomas
Observer Nevis Editor
(Charlestown, Nevis) – Weather watchers on both sides of the Atlantic are predicting there will be even more hurricane activity this year than they had called for just two months ago.
Tropical Storm Risk of the United Kingdom and the National Hurricane Center in the U.S. said this week that due to a change in wind patterns, the 2008 hurricane season will see more storms than they had previously expected.
TSR is a consortium of experts on insurance, risk management and seasonal climate forecasting led by UCL’s Benfield Hazard Research Centre.
Based on current and projected climate signals TSR predicts Atlantic basin and U.S. landfalling hurricane activity in 2008 will both be 90% above the long-term (1950-2007) norm. This compares to 35% above norm predictions issued on July 4, 2008.
According to TSR, the forecast has risen due to the establishment in July of tropospheric wind patterns which favor increased hurricane activity. Once formed, these unusual winds,tend to persist through the main hurricane months of August and September.
TSR’s updated hurricane prediction includes:
• A 97% probability of an above-normal Atlantic hurricane season, a 3% probability of a near-normal,season and a negligible chance of a below-normal season.
• 18 tropical storms for the Atlantic basin as a whole, with nine of these being hurricanes and four or five,of these hurricanes being intense in category. This compares to long-term norm values of ten, six and,three respectively.
• Five tropical storm strikes on the U.S., of which two will be hurricanes.
• One hurricane strike on the Caribbean Lesser Antilles.
If verified, the total of 18 tropical storms would be the equal third highest total recorded in a North Atlantic,season since 1950.
Professor Mark Saunders, the TSR lead scientist and Head of Weather and Climate Extremes at the
Benfield UCL Hazard Research Centre at University College London says there is now a high likelihood that 2008 will be a very active hurricane season.
The forecasters in the U.S. are sounding much the same warnings.
The American agency has increased the likelihood of an above-normal hurricane season and has raised the total number of named storms and hurricanes that may form. Forecasters attribute this adjustment to atmospheric and oceanic conditions across the Atlantic Basin that favor storm development – combined with the strong early season activity.
The NHC now projects an 85 percent probability of an above-normal season – up from 65 percent in May. The updated outlook includes a 67 percent chance of 14 to 18 named storms, of which seven to 10 are expected to become hurricanes, including three to six major hurricanes of Category 3 strength or higher on the Saffir-Simpson Scale. These ranges encompass the entire season, which ends November 30, and include the five storms that have formed thus far.
In May, the outlook called for 12 to 16 named storms, including six to nine hurricanes and two to five major hurricanes. An average Atlantic hurricane season has 11 named storms, including six hurricanes and two major hurricanes.
“Leading indicators for an above-normal season during 2008 include the continuing multi-decadal signal – atmospheric and oceanic conditions that have spawned increased hurricane activity since 1995 – and the lingering effects of La Niña,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center. “Some of these conditions include reduced wind shear, weaker trade winds, an active West African monsoon system, the winds coming off of Africa and warmer-than-average water in the Atlantic Ocean.”
Another indicator favoring an above-normal hurricane season is a very active July, the third most active since 1886. Even so, there is still a 10 percent chance of a near normal season and a five percent chance of a below normal season.