Hanna Track, Intensity Seen As Unpredictable

Two catastrophe modeling firms cautioned today that the track and intensity of Tropical Storm Hanna is currently highly unpredictable.

Christine Ziehmann, director of model management at Newark, Calif.-based Risk Management Solutions, said forecasts suggest Hanna will gradually re-strengthen to hurricane intensity before striking the U.S. coast.

But Ms. Ziehmann noted that “the systems around the storm are complex at the moment, so confidence in the intensity forecast is lower than usual.”

The National Hurricane Center forecast has Hanna striking the Georgia coast as a hurricane on Friday evening, but like the intensity, the track confidence remains low until Hanna’s motion becomes better defined.

Hanna dumped heavy rain on the Southeastern Bahamas, the Turks and Caicos Islands, and Haiti, which was already saturated by rain from Hurricane Gustav last week. Accumulations of 4-to-8 inches were expected, with isolated amounts up to 12 inches.

AIR Worldwide in Boston said there is considerable uncertainty with respect to Hanna's track through the Bahamas.

The firm mentioned that the National Hurricane Center’s most likely track has Hanna skirting the Bahamas to the north and well away from the most heavily populated islands of New Providence (and the capital Nassau) and Grand Bahama.

AIR said other models show a more southerly track directly through the middle of the islands. Given that the moderate wind shear that Hanna was experiencing was expected to diminish, some additional intensification is likely, AIR said.

However, AIR noted that dynamic forecast models are in reasonably good agreement that Hanna will speed up and eventually make a U.S. landfall somewhere between Savannah, Ga., and Myrtle Beach, S.C.

Ms. Ziehmann said the eastern coast of Florida, Georgia and South Carolina “should all keep an eye on Hanna.”

Should Hanna make landfall as a hurricane, carriers in the Southeast face a potential risk worth $25.5 billion, according to Highline Data, a unit of Summit Business Media, the parent company of National Underwriter.

Regarding other storms that are in the Caribbean, RMS said that forecast models for Tropical Storm Ike are in good agreement that Ike will likely intensify to a hurricane within the next 24 hours, and will continue on a westward track due to a building mid-level high in the Atlantic.

Behind Ike is Tropical Storm Josephine. Satellite intensity estimates that it will strengthen only modestly over the next five days, as the shear environment will become steadily less favorable, RMS said.

Hurricane Gustav, meanwhile, moved inland and was downgraded to a depression, but was causing flooding and a threat of tornados in parts of Louisiana, Texas, Arkansas and Mississippi.

According to the Highline Data’s “Gustav Exposure Report,” State Farm Illinois Group is the carrier in Louisiana with the greatest exposure for personal and commercial lines, with $794 million and $45 million in premiums in the region, respectively.

Fidelity National Financial faces the greatest federal flood exposure, with $61.8 million in premiums at risk in the region.

RMS said its reconnaissance teams will be reaching the areas that are reported to be worst hit later today, around the landfall area in Houma and Morgan City, La.