Extended Abstract (3.0M)5A.5
Providing short-fused warnings for the onset of extreme hurricane winds—a final opportunity to minimize casualties
Scott M. Spratt, NOAA/NWSFO, Melbourne, FL; and B. C. Hagemeyer and D. L. Jacobs
The primary responsibility of National Weather Service (NWS) Forecast Offices (WFOs) is to protect lives and property through the issuance of short-fused warnings when severe weather becomes imminent. While well established policies are in place to accommodate the issuance of severe thunderstorm and tornado warnings during extra-tropical situations (severe squall lines, derechos, discrete supercells, etc.), similar short-fused warning strategies have not been employed for extreme winds associated with tropical cyclone landfalls. Recently, however, a methodology was devised to provide local warnings for the rapid and imminent onset of extreme winds associated with major hurricanes, thus providing a final opportunity for the protection of lives.
On 13 August 2004, major Hurricane Charley made landfall along the southwest Florida coast, then accelerated rapidly northeast across the central Florida peninsula. This track brought the core of the strongest winds directly across Orlando, Florida, the most densely populated interior city of the state. Given the unprecedented, imminent occurrence of extreme winds (gusts over 100 mph) far from the coast, innovative measures were taken to warn inland locations along the projected track of the hurricane eye-wall convection. A special bulletin was produced and disseminated to prompt immediate action for the protection of lives prior to the onset of destructive winds and the likelihood of embedded tornado-like damage. The bulletin was issued as a tornado warning to ensure maximum visibility and universal dissemination.
The purpose of the special warning was to emphasize the rapid and imminent onset of extreme winds with a high potential for damage and casualties. The warning recommended the same protective actions as for tornadoes and used concise and explicit terminology to urge residents to take actions, while providing a distinction from traditional tornado warnings. Special tornado warnings for extreme winds also were issued in September 2004 when major Hurricane Jeanne made landfall along the southeast Florida coast.
Extensive post-storm air and ground surveys confirmed several tornado-like damage swaths containing significantly enhanced localized destruction along the eye-wall paths of Hurricane Charley and Jeanne. Despite extensive property damage, only two fatalities resulted as a direct result of the passage of the hurricanes across interior and east central Florida. The effectiveness of the unique warning strategy was further evident through positive feedback provided by several emergency managers and media representatives.
This conference presentation will detail the initial warning methodology as well as a subsequent multi-phased approach for establishing a new warning product for extreme hurricane winds. Radar imagery of the eye-wall features will be shown, along with documented examples of associated tornado-like damage enhancements.
Session 5A, RIsk Management
Tuesday, 25 April 2006, 8:00 AM-10:00 AM, Regency Grand BR 4-6
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Recorded presentation