Forecasters Predict an Active Atlantic Hurricane Season

FORT COLLINS, Colorado, May 5, 2006 (ENS) - The start of the Atlantic hurricane season is less than a month away, and forecasters are predicting more devastating storms this year. Employing a statistical system based on past trends, hurricane forecasters at Colorado State University are predicting a "very active" season with landfall probabilities "well above their long-period averages."

Their updated forecast, released in late April, projects 17 named storms, of which nine will become hurricanes.

Gone with the wind painted on the side of a smashed trailer damaged by Hurricane Rita. Johnson Bayou, Louisiana, November 16, 2005. (Photo by Marvin Nauman courtesy FEMA)

"Even though we expect to see the current active period of Atlantic major hurricane activity to continue for another 15 to 20 years, it is statistically unlikely that the coming 2006-2007 hurricane seasons, or the seasons that follow, will have the number of major hurricane U.S. landfall events as we have seen in 2004-2005," said Colorado State Professor William Gray.

The hurricane forecast team said the chances of a major hurricane making landfall on U.S. soil are:

• An 81 percent chance that at least one major hurricane will make landfall on the U.S. coastline in 2006. The long-term average probability is 52 percent.

• A 64 percent chance that a major hurricane will make landfall on the U.S. East Coast, including the Florida Peninsula. The long-term average is 31 percent.

• A 47 percent chance that a major hurricane will make landfall on the Gulf Coast from the Florida Panhandle west to Brownsville. The long-term average is 30 percent.

The team also predicted above-average major hurricane landfall risk in the Caribbean.

The good news is that NASA oceanographers agree the recent La Niña in the eastern Pacific Ocean is not expected to have an effect on the Atlantic hurricane season this year. That is good news because normally a La Niña tends to increase Atlantic hurricane activity and decrease Pacific Ocean hurricanes.

Although La Niña occurs in the Pacific, it affects weather in the Atlantic Ocean as well, through changes in the winds. La Niña changes the wind patterns in the upper and lower levels of the atmosphere, which makes it easier for hurricanes to form in the Atlantic and harder in the eastern Pacific.

David Adamec, an oceanographer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland said that “the current temperature signal at the end of April is near normal and the ocean surface temperature has not yet caused the atmosphere to respond in a La Niña-like way.”

Forecasters and other scientists still expect a greater than average number of Atlantic Ocean hurricanes this year, but La Niña will not be a factor in that. The more active season is expected because of other environmental conditions favorable to hurricanes, such as the location of the Bermuda high removing much of the wind shear in the western Atlantic that thwarts hurricanes, and warm sea surface temperatures in the Gulf of Mexico.

Bill Patzert, oceanographer at NASA’s Jet Propulsion Laboratory in Pasadena, California observed, “The recent increased frequency of the hurricanes is thought to be part of a larger decades-long cycle of alternating increases and decreases of hurricane activity. The current busy hurricane cycle began in 1995 and could continue for another 10 to 25 years."

"For the U.S. East and Gulf coasts, the fading La Niña is a real good thing," Patzert said, "but Atlantic sea surface temperatures are still very toasty. It’s the summer conditions that will dictate the fall hurricane activity, and I suspect those forecasts will be modified."

Florida and the Gulf Coast were ravaged by four landfalling hurricanes in each of the past two years. Hurricanes Charley, Frances, Ivan and Jeanne caused devastating damage in 2004, followed by Dennis, Katrina, Rita and Wilma in 2005.

This image was captured by the MODIS instrument on the Aqua spacecraft on October 24, 2005. It shows Hurricane Wilma departing Florida after crashing into the western side of the state early that morning. A powerful Category 5 hurricane, Wilma set the all time record for the lowest recorded pressure in the Atlantic basin. (Photo courtesy NASA)

The Landfall Probability website, online at: www.e-transit.org/hurricane, is the first publicly accessible Internet tool that adjusts landfall probabilities for regions, sub-regions and counties based on the current climate and its projected effects on the upcoming hurricane season.

The site provides U.S. landfall probabilities for 11 regions, 55 sub-regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine.

Professor Gray and Phil Klotzbach of the Colorado State University hurricane forecast team update the site regularly with assistance from the GeoGraphics Laboratory at Bridgewater State College in Massachusetts.

The hurricane team's forecasts are based on the premise that global oceanic and atmospheric conditions - such as El Niño, sea surface temperatures and sea level pressure - that preceded active or inactive hurricane seasons in the past provide meaningful information about similar trends in future seasons.

For 2006, Gray and the hurricane forecast team expect continued warm tropical and north Atlantic sea-surface temperatures, prevalent in most years since 1995, as well as neutral or weak La Niña conditions - a recipe for greatly enhanced Atlantic basin hurricane activity.

Klotzbach and his team of forecasters report that the Atlantic Ocean "remains anomalously warm."

The National Oceanic and Atmospheric Administration (NOAA) confirmed the warming of the Atlantic Ocean on Monday, noting that the region where hurricanes originate has warmed several tenths of a degree Celsius over the 20th century.

According to NOAA, new climate models suggest that "human activity, such as increasing greenhouse gas emissions into the atmosphere, may contribute significantly to this warming."

"This very long-term increase in temperature may seem small but is comparable in magnitude to shorter time-scale, multi-decadal changes that many scientists now believe contribute strongly to an increase in hurricane activity in the Atlantic," said Thomas Knutson, lead author of the paper and a senior research meteorologist at the NOAA Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey.

"The challenge," said Knutson, "is to understand the relative roles of anthropogenic and natural factors in producing these temperature changes - and this study is a step in that direction - and then to determine whether and how these long-term changes in temperature could be affecting Atlantic hurricane activity."

Hurricane Katrina on August 28, 2005, at 11:45 am EDT as a Category 5 storm in the Gulf of Mexico, a day before it slammed into the Gulf Coast (Photo courtesy NOAA)

They will meet with emergency managers, media and the public. Cities on the route include Brownsville and Beaumont-Port Arthur, Texas; Mobile, Alabama; West Palm Beach and Tampa, Florida.

The five-city, five-day mission is intended to increase hurricane awareness and encourage preparedness in vulnerable coastal and inland communities along the Gulf coast and Florida.

"Educating the public is our continuing mission," said Max Mayfield, director of the NOAA National Hurricane Center in Miami. "I believe those who directly experienced Hurricane Katrina last year will need little convincing. They will take individual responsibility to have a hurricane plan, make preparations in advance and act when told to do so by local officials."

"It is the population that is inexperienced that concerns me," Mayfield said, "particularly in the very active period of hurricane activity we are likely to experience over the next 10 to 20 years."

Meanwhile, the Minerals Management Service has raised its estimate of the damage to oil and gas infrastructure from Hurricanes Katrina and Rita. The MMS increased the number of damaged pipelines from 183 to 457 and raised the number of large pipelines that were damaged from 64 to 101.

Of the large pipelines, only 32 have returned to service.

Of four major oil platforms that were damaged, three will return to service soon, says the MMS, and the fourth will return to service late this year.