Two groups of forecasters are predicting another busy hurricane season this year after coming off nearly spot-on predictions for a very active 2010 season.
The team of Philip Klotzbach and William Gray at Colorado State University’s (CSU) Tropical Meteorology Project are projecting 17 named storms in 2011, including nine hurricanes and five major hurricanes of Category 3 or higher on the Saffir-Simpson scale (sustained winds of 111 mph or higher).
The team said the numbers are close to what was experienced during the 2010 season in the Atlantic basin.
The hurricane season runs from June 1 through Nov. 30.
Separately, Weather Services International (WSI), part of the Weather Channel Companies, delivered the same 2011 prediction as CSU–calling for 17 named storms, nine hurricanes and five intense hurricanes of Category 3 or greater.
The predicted totals are well above the normal levels of 10 named storms, six hurricanes and two intense hurricanes.
This past season, both teams predicted a well above-average numbers of storms.
In June, at the start of the season, the CSU team called for 18 named storms, 10 hurricanes and five major hurricanes, while Andover, Mass.-based WSI called for 19 named storms, 11 hurricanes and five major hurricanes.
Both forecasts were close to the mark. There were actually 19 named storms, 12 hurricanes and five major hurricanes.
“The United States was extremely lucky in 2010 in that none of the 12 Atlantic basin hurricanes that formed crossed the U.S. coastline,” Mr. Klotzbach said in a statement. “On average, about one in four Atlantic basin hurricanes makes U.S. landfall, and therefore, we would expect to see more landfalling hurricanes in 2011.”
While noting the uncertainty in the forecast six months ahead of the season, CSU’s Mr. Klotzbach said that current upper ocean heat anomalies in the tropical Pacific mean an El Ni?o is unlikely, leading to a more active hurricane season in 2011.
An El Ni?o produces wind and atmospheric conditions that are not conducive to the development of hurricanes.
“This forecast is based on an extended-range early December statistical prediction scheme we’ve developed based on 58 years of data,” Mr. Gray said. “At this point, we are uncertain whether La Ni?a conditions or neutral conditions are more likely for the 2011 hurricane season. Sea surface temperatures in the far North Atlantic remain at record warm levels, which is an indication that we are in an active multidecadal period for Atlantic hurricane activity.”
At WSI, Todd Crawford, chief meteorologist, noted that like last year, ocean temperatures in the Atlantic are expected to be above normal and wind shear is predicted to be favorable for storm formation. Mr. Crawford also said that WSI’s model calls for an increased chance of U.S. landfall in 2011, especially for the western Gulf states.
“The forecast numbers are quite similar to those prior to the 2008 season when hurricanes Dolly, Gustav and Ike impacted Louisiana and Texas,” Mr. Crawford added.
Ike was the costliest hurricane to hit Texas, causing insured property damages of $9.8 billion, according to the Insurance Services Office. Much of the losses were shouldered by the state’s insurer of last resort, the Texas Windstorm Insurance Association. Ike ranks as the third costliest hurricane in U.S. history, causing more than $12.5 billion in insured losses.
Louisiana was impacted by the top three costliest hurricanes in U.S. history, including Hurricane Katrina in 2005, which cost insurers more than $41 billion.
CSU gave the following probabilities related to potential locations of 2011′s hurricanes:
E A 73 percent chance that at least one major hurricane will make landfall on the U.S. coastline in 2011. The long-term average probability is 52 percent.
E For the U.S. East Coast, including the Florida Peninsula, the probability of a major hurricane making landfall is 49 percent. The long-term average is 31 percent.
E For the Gulf Coast from the Florida Panhandle west to Brownsville, the probability is 48 percent. The long-term average is 30 percent.
E The team predicts the probability of a major hurricane making landfall in the Caribbean as 62 percent. The average for the last century is 42 percent.
The team has also updated the Landfall Probability website that provides probabilities of tropical storm-force, hurricane-force and major hurricane-force winds making landfall at specific locations along the U.S. East and Gulf coasts within a variety of time periods.