Hurricane Carlotta

Pre-Landfall 1 | Summary
Posting Date: June 15, 2012, 12:30:00 PM

As of the National Hurricane Center’s (NHC) 8:00 am (PDT) Advisory today, Hurricane Carlotta—which yesterday was a tropical storm—was about 120 miles south-southeast of the sparsely populated Mexican town of Puerto Ángel and 330 miles southeast of Acapulco, the popular tourist resort. The storm has maximum sustained winds of 80 miles per hour (making it a weak Category 1 storm on the Saffir-Simpson Hurricane Wind Scale) and is moving northwest at 12 miles per hour; this general motion is expected to continue through the night, though the storm’s forward speed is expected to slow. Carlotta is forecast to rapidly intensify this afternoon and evening, possibly reaching Category 2 strength as it approaches Mexico. On its current track, Carlotta should closely approach and possibly make landfall on Mexico’s southern coast near the small town of Puerto Ángel (in the state of Oaxaca) late tonight or tomorrow. The NHC’s most likely track brings Carlotta near, but not over land; however, the center of the storm may well pass sufficiently close to land to cause damage over the weekend. Carlotta may also closely bypass the coastline south of Acapulco, though again, it is not expected to move onshore. As of the NHC’s latest advisory, a hurricane warning is in effect for the Pacific coast of Mexico from Punta Maldonado to Acapulco; west of Acapulco, to Tecpán de Galeana, a hurricane watch is in effect. Hurricane conditions are expected within the hurricane warning area as early as tonight. Expected Damage If Carlotta reaches the projected Category 2 intensity and moves onshore, structural damage to non-engineered buildings may occur, particularly to roofs, while windows and the cladding on engineered structures could be damaged by impact from debris. Most insured residential structures on Mexico's west coast are made of confined masonry, which performs better than plain masonry under lateral wind loads because of its use of bond beams and columns. Commercial properties tend to be constructed of confined masonry or reinforced concrete. At present, however, a single national building code for structural design does not exist in Mexico. The enactment and adoption of building codes are subject to the actions of separate government departments in each of the more than 2,400 municipalities. At the same time, a large percentage of the residential housing built in Mexico every year—perhaps as high as 50%—is constructed without building permits, and thus may be more prone to damage. This is particularly evident in poorer regions of Mexico, including the states of Oaxaca and Guerrero, which are in Carlotta’s direct path. Large and destructive waves are expected to batter a long stretch of coast and cause widespread coastal flooding north and east of the region where Carlotta approaches land. Meanwhile, up to 5 inches of rain are expected in the Mexican states of Chiapas, Guerrero and Northern Oaxaca, and up to 10 inches could drench Southern Oaxaca. Along the Oaxaca coast, some isolated locations could experience 15-inch rainfall. This heavy precipitation could produce mudslides and flash flooding, including flooding further inland from the coast. At present, apart from government-issued watches and warnings, few other precautions or evacuations have been reported. The storm is projected to track north of Mexico's largest oil refinery, Pemex; so far, Pemex is operating normally. The Baja California resort town of Los Cabos, to the north, where world leaders will gather on Monday and Tuesday for the G20 summit, is far from the storm’s projected path. Forecast and Intensity In 1997, Hurricane Pauline made landfall in the same area Hurricane Carlotta is expected to impact tonight or tomorrow. Pauline paralleled the Mexican coastline before weakening slightly due to interaction with the mountainous terrain; the storm made landfall near Puerto Ángel as a strong Category 2 hurricane (stronger than Carlotta is forecast to become). The following day, the storm dissipated. Pauline produced significant rain (much like Carlotta is expected to do); Puente Jula received nearly 33 inches of rainfall. Tens of thousands of homes in some of Mexico’s poorest areas, including Oaxaca and Guerrero, were damaged by the passage of Pauline. The mudslides that resulted from Pauline’s heavy rains were fatal, killing up to 500 people. At present, Carlotta’s hurricane-force winds extend outward up to 25 miles; they will begin to interact with land several hours before Carlotta makes its closest approach. Once Carlotta does arrive at (or over) the coast, it is expected to weaken, reaching tropical storm strength by late Saturday. Its most substantial effect throughout the region will likely be from flooding. It should be noted that while Carlotta is projected to track south of the heavily commercialized resort town of Acapulco, the current forecast turns the storm out to sea as a tropical storm before Carlotta actually arrives there; even so, Acapulco and surrounding areas could be threatened by flooding. Additionally, any changes in the track and intensity of the current forecast for Carlotta could put Acapulco at risk from wind. The longer-term forecast for Hurricane Carlotta shows the storm turning away from Mexico’s coast, south of Acapulco, sometime Sunday—and then paralleling the coast of Mexico south of the resort city early next week. It could continue to deliver rain to the region at this time. Carlotta is the third named storm of the Pacific hurricane season. AIR’s tropical cyclone team is continuing to monitor this storm and will provide additional information as events warrant.

Pre-Landfall 1 | Downloads
Posting Date: June 15, 2012, 12:30:00 PM