BOSTON, August 25, 2012 – According to catastrophe modeling firm AIR Worldwide, Tropical Storm Isaac came ashore on Haiti’s southern peninsula at around 2:00 a.m. EDT this morning, August 25, 2012. The storm had intensified in the preceding hours and sustained winds at landfall were near 70 mph, just below hurricane strength (74 mph). Few reports of damage are available at this time apart from widespread downed trees and power lines; indeed several neighborhoods in Port-au-Prince have been left without power. However, wind damage can be expected to sheet metal siding and roofing, signage and awnings and other non-structural elements. Informally constructed homes and businesses may experience more significant damage, but such structures are unlikely to be insured.
As of today’s 8:00 a.m. EDT advisory from the National Hurricane Center (NHC), Tropical Storm Isaac has left Hispaniola and is moving to the northwest at 14 mph, towards Cuba. The storm is currently located about 95 miles east-southeast of Guantanamo. The center of Tropical Storm Isaac is expected to cross the westernmost, mountainous tip of Cuba and then track along the northern coast of the country, just offshore.
“The storm weakened somewhat as a result of its interaction with the island of Hispaniola and maximum sustained winds have now fallen to 60 miles per hour with higher gusts,” said Scott Stransky, senior scientist at AIR Worldwide. “However, Isaac is a very large system; tropical storm force winds (>39 mph) currently extend outward from the center an impressive 230 miles.”
Haiti and neighboring Dominican Republic, which share the island of Hispaniola, are continuing to experience heavy rainfall. Total accumulations of between 8 and 12 inches of rain are expected, with as much as 20 inches in some locations. This is expected to cause flash flooding and mudslides, particularly in Haiti, which has been largely deforested. The city of Les Cayes (estimated population 45,000) on the western end of Haiti’s southern peninsula is especially prone to flooding. Although communications out of Haiti are spotty, there are reports and pictures of street flooding in the Dominican Republic. Street flooding has also been reported in Puerto Rico.
Stransky continued, “Tropical Storm Isaac is currently heading toward Cuba, where it is expected to cut across the easternmost part of the island near Guantanamo.”
“Residential structures in Cuba are predominantly masonry, with wood frame representing a small part of the building stock. Directing and implementing policy related to housing is the responsibility of the Ministry of Construction. A large number of structures in Cuba are very old, and investments to maintain building quality have not been made. Commercial or tourism-related buildings have likely been given more attention over time and are better equipped to handle wind and flood hazards, but older residential structures will be less robust. If there is significant rainfall and flooding, some of these poorly maintained structures may experience damage to contents or structural walls due to breach of the building envelope. At the intensity projected for Isaac, only poor construction with light roofs or weak connections would experience significant wind damage.”
“The eastward shift in Isaac’s track late yesterday means that the storm will spend very little time over Cuba. However, it is crossing very high mountains, which will tend to disrupt the storm’s circulation. How much weakening Isaac will undergo remains to be seen; however, after the storm crosses Cuba, it will enter in an environment favorable to intensification, including low wind shear conditions and warm sea-surface temperatures. Isaac is expected to achieve hurricane status sometime tomorrow, before its arrival at the Florida Keys.”
AIR’s continues to monitor Isaac closely and will post additional information on the development and impacts of this storm as warranted by events.