Nine Hurricanes Predicted for Atlantic Basin

Nine Hurricanes Predicted for Atlantic Basin



   
April 2007 - A very active 
hurricane season is in store for the U.S. Atlantic Basin 
starting June 1, but not as active as the 2005 season, 
according to a team of hurricane forecasters at Colorado State 
University. 
Meteorologists William Gray and Phil Klotzbach anticipate 17 
named storms in the Atlantic basin between June 1 and November 
30, of which nine will become hurricanes. 
Of those nine, the team predicts that five will develop into 
intense or major hurricanes - rated category 3, 4 or 5 on the 
Saffir/Simpson scale - with sustained winds of 111 miles per 
hour or greater. 
"We are calling for a very active hurricane season this year, 
but not as active as the 2004 and 2005 seasons," said 
Klotzbach. "Based on our latest forecast, the probability of a 
major hurricane making landfall along the U.S. coastline is 74 
percent compared with the last-century average of 52 percent."
 Colorado State University hurricane forecasters William Gray, 
left, and Phil Klotzbach work with the Tropical Meteorology 
Project. 
The team's forecasts are based on the premise that global 
oceanic and atmospheric conditions - such as El Nino, sea 
surface temperatures and sea level pressures - that preceded 
active or inactive hurricane seasons in the past provide 
meaningful information about similar trends in future seasons.
 For 2007, the forecasters expect continued warm tropical and 
north Atlantic sea surface temperatures, prevalent in most 
years since 1995, as well as neutral or weak La Nina 
conditions - a recipe for greatly enhanced Atlantic basin 
hurricane activity. 
These factors are similar to conditions that occurred during 
the 1952, 1964, 1966, 1995 and 2003 seasons. The average of 
these five seasons had well above-average activity, and 
Klotzbach and Gray predict the 2007 season will have activity 
in line with the average of these five years. 
No hurricanes made landfall along the U.S. coastline last 
year. The 2006 season developed a total of 10 named storms, 
five hurricanes and two major hurricanes. 
The 2005 season, considered unusual by the Colorado State 
forecast team, there were 27 named storms, 15 hurricanes and 
seven intense hurricanes. 
Long-term averages are 9.6 named storms, 5.9 hurricanes and 
2.3 intense hurricanes per year. 
A Category 5 storm, Wilma became the 12th hurricane of the 
2005 Atlantic hurricane season in October, making the 2005 
season became the most active on record. 
The Colorado State team has cautioned against reading too much 
into the hurricane seasons of 2004 and 2005 when Florida and 
the Gulf Coast were ravaged by four landfalling hurricanes 
each year. Hurricanes Charley, Frances, Ivan and Jeanne caused 
devastating damage in 2004, followed by Dennis, Katrina, Rita 
and Wilma in 2005. 
"The activity of these two years was unusual, but within the 
natural bounds of hurricane variation," said Gray, who began 
forecasting hurricane seasons at Colorado State 24 years ago. 
"Following the two very active seasons of 2004 and 2005, 2006 
experienced slightly below-average activity with no 
landfalling hurricanes." 
"We've had an upturn of major storms since 1995," Gray said. 
"We think this upturn of major storms will continue for 
another 15 or 20 years." 
Gray does not attribute changes in recent and projected 
Atlantic hurricane activity to human-induced global warming. 
"Although global surface temperatures have increased over the 
last century and over the last 30 years, there is no reliable 
data available to indicate increased hurricane frequency or 
intenvironment newsity in any of the globe's seven tropical cyclone basins, 
except for the Atlantic over the past 12 years," Gray said. 
"Meteorologists who study tropical cyclones have no valid 
physical theory as to why hurricane frequency or intenvironment newsity 
would necessarily be altered significantly by small amounts of 
global mean temperature change," he said. 
Gray and Klotzbach predict tropical cyclone activity in 2007 
will be 185 percent of the average season. By comparison, 2005 
witnessed tropical cyclone activity that was about 275 percent 
of the average season. 
"In December and January, we had a weak to moderate El Nino 
event in the tropical Pacific Ocean. When you have El Nino 
conditions during the hurricane season, it increases vertical 
wind shear across the tropical Atlantic and typically results 
in a weaker tropical cyclone season," Klotzbach said. 
"However, we've seen El Nino conditions dissipate quite 
rapidly late this winter, so we do not think that's going to 
be an inhibiting factor this year," said Klotzbach. "Also, we 
have warm Atlantic sea surface temperatures this year which 
we've seen just about every year since 1995." 
U.S. Air Force hurricane hunters fly into the eye of an 
Atlantic hurricane. 
Gray and Klotzbach said there is a 74 percent chance that at 
least one major hurricane will make landfall on the U.S. 
coastline in 2007. The long-term average probability is 52 
percent. 
There is a 50 percent chance that a major hurricane will make 
landfall on the U.S. East Coast, including the Florida 
Peninsula, they said. The long-term average is 31 percent. 
They predict a 49 percent chance that a major hurricane will 
make landfall on the Gulf Coast from the Florida Panhandle 
west to Brownsville, while the long-term average is 30 
percent. 
The team also predicted above-average major hurricane landfall 
risk in the Caribbean. 
"We were quite fortunate last year in that we had no hurricane 
landfalls," Klotzbach said. "The 2006 season was only the 12th 
year since 1945 that the United States witnessed no hurricane 
landfalls." 
Probabilities of tropical storm-force, hurricane-force and 
intense hurricane-force winds occurring at specific locations 
along the U.S. East and Gulf Coasts within a variety of time 
periods are listed on the forecast team's Landfall Probability 
website. 
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. 
Online at: http://www.e-transit.org/hurricane, the site 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. 
Klotzbach and Gray update the site regularly with assistance 
from the GeoGraphics Laboratory at Bridgewater State College 
in Massachusetts. 

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