WSI Increases Its Forecast from 15 to 18 Named Storms, Still Expects 8 Hurricanes and 4 Intense Hurricanes for 2011 Season

Weather Authority Anticipates an Active Remainder of Tropical Season with Further US Landfall Risk Following Irene

Andover, MA, August 24, 2011 — WSI (Weather Services International) has increased its 2011 tropical forecast to 18 named storms, 8 hurricanes and 4 intense hurricanes (category 3 or greater). These 2011 forecast numbers are above the long-term (1950-2010) averages of 12 named storms, 7 hurricanes and 3 intense hurricanes, and are slightly higher than the averages from the more active recent period (1995-2010) of 15/8/4. This latest forecast represents an increase from the previous forecast for 15 named storms, 8 hurricanes and 4 intense hurricanes.

“Before Irene, this season had been characterized by a slew of weak/moderate tropical storms. To date, we have already had 9 named storms; and we’re still two to three weeks away from the mid-point of the season,” said WSI Chief Meteorologist Dr. Todd Crawford. “Because of this, we had no choice but to increase our named storms forecast from 15 to 18; and the current pace suggests that even this number may be too low. Most of the important drivers for tropical activity continue to indicate that the remainder of the season should be quite active, including warmer-than-normal North Atlantic water temperatures, very low surface pressures in the main development region and no impending El Nino event. On the other side of the ledger, the atmosphere in much of the tropical Atlantic has been less unstable than normal this season so far, limiting the strength of the storms that have formed, as yet. Irene is just the first hurricane of the season. So, while we have increased the forecast for total number of named storms, we have maintained our expectation for 8 hurricanes and 4 intense hurricanes.”

Crawford also indicated that the Gulf Coast was under the greatest threat for hurricane landfall for the remainder of the season (after Irene).

“The hurricane drought in 2009 and 2010 was 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. Irene may break that streak. The recent lack of US landfalls was, in large part, driven by persistent, atmospheric blocking in the North Atlantic. This negative phase of the North Atlantic Oscillation (NAO) is typically associated with more East Coast and recurving storms, and fewer storms in the Gulf. The atmospheric pattern associated with the negative NAO has remained in place much of this summer. It is primarily responsible for recurving Irene before she got into the Gulf.”

“For the rest of the season, however, WSI expects the North Atlantic blocking pattern to relax a bit as September arrives. This may open the Gulf up to an increased threat for hurricane landfalls. However, multiple US landfalls would not be particularly unusual, because the mean number of US landfalls since 1995 has been 2.26. Further, the western Gulf States have averaged 0.94 landfalls a season since 1995.”

“Even though there’s been a lack of landfalls during the past couple of years, as always, it’s important for those of us in all US coastal areas to prepare for the upcoming hurricane season and not to let our guards down.” Dr. Crawford added.

Energy traders, insurance professionals and risk managers look to WSI for accurate, timely weather information around the clock and across the globe. The next seasonal forecast update, which will include forecasts for late fall and early winter temperatures, will be issued on September 20. The final update for the 2011 tropical season will be released on September 21.

About WSI
WSI (Weather Services International) is the world's leading provider of weather-driven business solutions for professionals in the energy, insurance, aviation and media markets, as well as multiple federal and state government agencies. WSI is a member of The Weather Channel Companies and is headquartered in Andover, Massachusetts with offices in Birmingham, England. The Weather Channel Companies are owned by a consortium made up of NBC Universal and the private equity firms The Blackstone Group and Bain Capital. 

Linda Maynard
WSI Corporation
(978) 983-6715

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