Weather Services International (WSI) have released revised predictions for the number and type of storms for the 2011 storm season emanating from the Atlantic Ocean.
WSI predicts 15 named storms, 8 hurricanes and 4 intense hurricanes rated at category 3 or greater.
These forecasts are above the long-term average calculated between 1950 and 2010 of 12 named storms, 7 hurricanes, and 3 intense hurricanes, but do match the more active recent period calculated between 1995 and 2010.
The current set of predictions is a reduction from the previous set made in December for 17 named storms, 9 hurricanes and 5 intense hurricanes.
“We have reduced our forecast numbers to ‘active-normal’ levels since the recent North Atlantic weather pattern has resulted in a cooling of the tropical Atlantic sea surface temperatures. Further, the La Nina event weakened a bit more quickly than we first expected, reducing the possibility of a favorable wind shear environment during the upcoming tropical season,” said WSI Chief Meteorologist Dr. Todd Crawford.
“We do expect another active season in 2011, although not to the level of 2005 or 2010. However, while we expect less overall activity this year, we do expect a much more impactful season along the US coastline. The US has been spared from any landfalling hurricanes since 2008, and the hurricane drought in 2009 and 2010 is relatively rare in the historical record. In fact, the US has not had a three-year stretch without a hurricane landfall since the 1860s. Further, 80 percent of all years in the historical dataset have had at least one hurricane landfall in the US. Our recent good fortune in avoiding landfalling hurricanes is not likely to last.”
Crawford also indicated that the Gulf Coast was under a significant threat for hurricane landfall in the upcoming season.
“The lack of US landfalls in 2010 was primarily due to a persistent western Atlantic trough that essentially protected the US East Coast from any direct hits. We do not expect this feature to be in place this year during late summer and fall when most tropical storms occur. Further, the Gulf and Caribbean sea surface temperatures are particularly warm this year, and we expect more development in these regions and less in the eastern tropical Atlantic. Storms developing in the Gulf and Caribbean are a much greater threat to make landfall along the US coast than those that develop off the coast of Africa.”
“For this reason, and since our hurricane landfall prediction model suggests sharply increased chances of US landfall in 2011, especially in the western Gulf states, we expect two or three landfalling hurricanes this season. This is not particularly unusual, since historically 43% of years have had multiple hurricane landfalls. The forecast numbers from our model are quite similar to those prior to the 2008 season, when Hurricanes Dolly, Gustav, and Ike impacted Louisiana and Texas.”
Since 2006, when WSI began making tropical seasonal forecasts, its track record has been better than Tropical Storm Risk (TSR) and Colorado State University. Click here for the track record charts.