First tropical storm of the hurricane season strikes
The first tropical storm of this year's hurricane season tore across Central America this weekend.
AIR issued the following incident assessment.
The start of the 2010 East Pacific hurricane season was marked by a short-lived, but deadly storm that wreaked havoc in Central America over the weekend. Tropical Depression 1-E formed off the coast of Guatemala on Saturday. Benefitting from low wind shear and sea surface temperatures of 30°C, the system briefly strengthened to Tropical Storm Agatha before making landfall near Guatemala’s border with Mexico. Agatha managed to achieve wind speeds of 45 mph—a minimal tropical storm—before being broken up by Guatemala’s mountainous Pacific coast. By early Sunday, it was once again a tropical depression.
Despite unimpressive wind speeds, the storm brought more than a foot of rain to Guatemala and parts of Honduras and El Salvador, triggering flooding and mudslides that washed away roads, bridges, homes and businesses. "The region’s coastal mountain ranges enhance precipitation," explained Dr. Tim Doggett, principal scientist at AIR Worldwide. "The warm, moist air is forced to rise and as the rising air cools and water vapor condenses, additional clouds form and boost precipitation." In an unfortunate coincidence, the storm coincided with the eruption last week of the Pacaya volcano, southwest of Guatemala’s capital. The mix of mud and ash will undoubtedly make clean-up efforts more challenging.
Construction in Guatemala and El Salvador is dominated by unreinforced masonry (URM) construction. "While wind speeds of 45 mph would not be expected to cause significant damage to URM buildings, it is quite vulnerable to flooding," said Dr. Doggett. "Traditional adobe construction—another highly vulnerable construction type—is also fairly common, particularly in more rural areas, which is where the bulk of the damage occurred."
Officials in Guatemala are reporting that more than 3,500 homes were damaged. Meanwhile, a sinkhole opened up in Guatemala City, swallowing a three-story building. It has been suggested, though not confirmed, that Agatha’s heavy rainfall triggered the event.
At least two dams were reported to be under stress over the weekend, though the immediate danger seems now to have diminished. Yesterday, the presidents of both El Salvador and Honduras declared states of emergency.
Because much of what was damaged in this storm is unlikely to have been insured, AIR does not expect significant insured losses.
