Predictions Based Solely On Atlantic Hurricane Activity Can Lead To Overestimation Of Risk
- Predictions Based Solely On Atlantic Hurricane Activity Can Lead To
Overestimation Of Risk
Boston MA (SPX) Jan 08, 2008
AIR Worldwide has announced results of the latest research by its team of
scientists into the link between the formation of hurricanes in the
Atlantic basin and U.S. landfall activity. The latest findings provide a
context for better understanding the 2004-2007 hurricane seasons and
demonstrate that using Atlantic basin activity as a proxy for landfall
activity can lead to erroneous estimates of both landfall risk and
potential insured losses.
"By only focusing on the 2004 and 2005 seasons, it is easy to forget that
every hurricane season is unique and actual landfall activity is a
function of complex interactions between a range of environmental factors
such as genesis location, sea surface temperatures and the depth of warm
ocean waters, wind shear and atmospheric steering," said Dr. Peter
Dailey, director of research in atmospheric science at AIR Worldwide.
"A higher number of tropical storms in the Atlantic basin does not
translate to an equivalent increase in hurricanes or landfalling
AIR researchers found that a storm"s genesis location, or starting point,
greatly influences its probability of making landfall along the North
American coastline. The pattern of hurricane genesis locations changes
from year to year and by comparing the pattern for a particular season to
long-term climatological patterns, one can better understand why in some
years the proportion of storms making landfall is high, while in other
years it is low.
AIR"s research can be used to analyze the landfall probabilities of the
two strongest storms of the 2007 season " Category 5 hurricanes Dean and
Felix " based on their genesis locations. Dean and Felix, which were the
only storms this year to achieve greater than Category 1 status, both
took southerly tracks across the Caribbean and eventually made landfall
along the coasts of Mexico and Central America.
"Contrary to popular belief, the U.S. did not `dodge a bullet" with
respect to Hurricanes Dean and Felix," stated Dr. Dailey. "Based on where
these storms formed and how they would track under typical steering
conditions, our research shows that Hurricane Dean had a low chance of
making landfall as a hurricane and Felix was much more likely to strike
the Mexico or Central America coastline than the U.S."
Sea surface temperatures in the Atlantic basin have been warmer than
average every year since 1995. However, the percentage of Atlantic basin
storms that make U.S. landfall as hurricanes has been below the long-term
average of 14 percent in nine of those thirteen seasons. In 2007, only
one of fifteen named storms made U.S. landfall as a hurricane, or less
than 7 percent. More significantly, total wind energy in 2007 was 33
percent below average despite two Category 5 storms.
"The seasonal forecasters correctly projected that a higher-than average
number of tropical storms would form in the basin in 2007," continued Dr.
Dailey. "But it"s much more difficult to predict not only how many of
these storms will become hurricanes, but more importantly how many will
make landfall as hurricanes. Like many past seasons, the 2007 season
showed that an elevated number of tropical storms does not always
translate to more hurricanes or more landfalling hurricanes.
In 2007, sea surface temperatures were not as warm as some scientists
expected and significant wind shear suppression by La Nina did not
materialize as they had anticipated. Clearly there"s a danger in assuming
that one or two single seasons are indicative of a paradigm shift in
hurricane risk. While 2004 and 2005 were both very active seasons, they
were not good predictors of activity in 2006 and 2007."
AIR employs one of the largest teams of professional meteorologists in
the world of risk management and will continue to produce transparent,
quantifiable and reproducible research on hurricane genesis and steering
to provide an improved understanding of the factors that influence
hurricane landfall probability.
In addition to a standard view of hurricane landfall risk based on over
100 years of historical data and over 20 years of research and
development, the AIR U.S. hurricane model includes an alternative view of
landfall risk under warm sea-surface temperature conditions.
Under warm ocean conditions, AIR estimates U.S. insured losses to be 15
percent higher than the long-term average. In some areas, such as the
Northeast, AIR expects little difference from the long-term average. AIR
intends to again submit its U.S. hurricane model for certification under
the rigorous standards of the Florida Commission on Hurricane Loss
Projection Methodology (FCHLPM) in 2008 for the twelfth consecutive year.