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Monitoring Hurricane Wilma's Storm Surge
Residents in the Southeastern United States were still reeling from Hurricanes Katrina and Rita when Hurricane Wilma came on the scene, the third category 5 storm of the Atlantic hurricane season and, at its peak, the most intense tropical cyclone ever recorded in the Atlantic Basin (on the basis of its low central pressure). By the time Hurricane Wilma struck southwestern Florida on the morning of October 24, 2005 (then a category 3 storm), the U.S. Geological Survey (USGS) had established 30 temporary hydrologic stations to measure storm surge along the coast where the hurricane was projected to make landfall. Two days before Wilma hit, USGS teams from Louisiana (Ruston) and Florida (Tampa, Fort Lauderdale, and Fort Myers) coordinated their efforts to install the temporary gages at strategic locations. Even though the measured storm surge was not as high as predicted, the damage was still widespread. This monitoring effort is one example of how the USGS can provide important scientific information in a crisis. Hurricane Wilma broke numerous records in what was arguably "the most devastating hurricane season the country has experienced in modern times," according to retired Navy Vice Admiral Conrad C. Lautenbacher, Undersecretary of Commerce for Oceans and Atmosphere and the National Oceanic and Atmospheric Administration (NOAA) Administrator. Wilma marked the first time that three category 5 storms occurred in one Atlantic hurricane season, and it reached category 5 intensity at a record rate: over the course of just 24 hours, from October 18 into October 19, Wilma strengthened from a 70-mph tropical storm to a 170-mph category 5 hurricane, unprecedented for an Atlantic tropical cyclone. At its peak on October 19, the hurricane's sustained wind speed was about 185 mph and its minimum central pressure was estimated at 882 mbars, a record low for a hurricane in the Atlantic Basin. Wilma weakened slightly, to a category 4 storm, before hitting Mexico's Yucatán Peninsula late on October 21. There it stalled for a day, dumping more than 5 ft of rain in some areas and causing severe damage. Wilma's intensity was reduced by its passage over land, but as the storm moved into the Gulf of Mexico and approached Florida, it reintensified to category 3, with maximum sustained winds of 115 mph and hurricane-force winds extending outward 85 mi from the center (see NOAA's Hurricane Wilma advisory 35, 11:00 p.m. EDT, Oct. 23, at URL http://www.nhc.noaa.gov/archive/2005/pub/al242005.public.035.shtml). A storm surge of 9 to 17 ft above normal tide levels was predicted for Florida's southwest coast and areas south of the projected storm path. The actual storm surge was determined to be about 3 ft, but this estimate may be revised as more data become available for analysis.
Personnel in the USGS offices in Louisiana and Florida recognized the potential for measuring the storm surge from this impressive hurricane. A team from Ruston, La., was quickly dispatched to Fort Myers, Fla., with pressure transducers for measuring water height and monitoring stands to hold each transducer at a constant elevation during the storm. The goal was to establish 30 temporary gaging stations along Florida's southwest coast where landfall was expected. The Fort Myers office lent personnel who designed the monitoring network and assisted with installation and removal of the stations. The Tampa, Fla., office lent personnel to assist in the site installation, and the Fort Lauderdale, Fla., office assisted in coordinating the effort.
Although damage from the hurricane was widespread, impact from the storm surge seemed minimal, with wind and rain causing most of the damage. Florida's southwest coast was mostly spared because the storm struck a sparsely populated area; however, Florida's east coast fared much worse because the storm hit heavily populated parts of Miami-Dade, Broward, and Palm Beach Counties. Posthurricane storm-surge assessment is currently underway. Tasks that still need to be completed include (1) surveying the 30 monitoring sites to determine their elevations relative to a "local datum," a plane of equal elevation with which all the measured water heights can be compared; (2) quality-assuring the data; and (3) generating a storm-surge map tied to the local datum. The results of this effort demonstrate how effective and efficient the USGS can be when a crisis is at hand, and they manifest the need for a national plan for rapid deployment of storm-surge instrumentation. Thanks to all of the USGS personnel who put in long days to make this monitoring effort possible, including Ben McGee and Burl Goree (Ruston, La.), Kevin Hubbs and Ray Dupuis (Tampa, Fla.), Gene Krupp, Sara Hammermeister, Lars Soderqvist, Craig Thompson, Jessica Flanigin, and Eduardo Patino (Fort Myers, Fla.), and Scott Prinos (Fort Lauderdale, Fla.).
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in this issue:
Taiwanese Scientists Visit the WCMG Team Andrew Stevens Joins WCMG Team
February 2006 Publications List |
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U. S. Department of the Interior | U.S. Geological Survey
