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The need for Post Storm Data Acquisition (PSDA) has been a reality for decades. Following Hurricane Hugo efforts were made to formalize PSDA within the Federal community, but this effort was not successful. In the aftermath of Hurricane Andrew, it was documented that Federal offices were inundating the disaster site in an effort to preserve data. The Federal Emergency Management Agency's Hurricane Andrew Report lists this problem as a "finding" that needed action. The action was assigned to the National Weather Service (NWS). This action item far exceeded the capabilities of the NWS and the action was then directed to the Office of the Federal Coordinator for Meteorological services (OFCM). The OFCM invited various Federal agencies to participate in the development of a Federal Plan for Post Storm Data Acquisition. The result was the development and implementation of a plan that employed the concepts of rapid deployment and pre-deployment to significant natural hazard events. The initial deployment was to the island of Guam following Super Typhoon PAKA in December 1997. Although well-intended, the timing was not the best for optimum effectiveness. Distance and time of year (holiday season) played a large role in how the PSDA Quick Response Team performed.
The new director of the NWS, John J. Kelly, has given the PSDA effort a high priority, and his goals are to use the teams' efforts to assess NWS services and to get the research community's help in improving those services. The PSDA reports and weather data may go onto the OFCM website (the PAKA report should be completed by late August).
Super Typhoon PAKA weakened slightly as its eye passed between Guam and Rota on 16 December 1997. A controversial peak wind gust of 235 mph was reported in the media from Anderson Air Force Base (AFB) on the northern end of Guam. The two primary goals of this particular PSDA team were to check this wind report and others, and to assess the sustained and gust windspeeds in PAKA and their associated damage patterns. The instrument from which the highest winds were measured was a hot-film anemometer, but heavy rain in the eye wall coupled with power surges probably contaminated the data. Therefore, the PSDA team considers the record unreliable. The highest winds other than the Anderson AFB were 150 mph with gusts up to 185 mph and there were 8-10 hours of sustained typhoon-force winds over parts of Guam. The island also had up to 20" rainfall and was under a hurricane/typhoon watch/warning status for 10 days. This may have contributed to public complacency, along with PAKA's dropping below Super Typhoon status as it approached. Aerial and ground damage surveys revealed minor damage to buildings and vegetation, and no evidence of meso-vortices. There were no fatalities.
Major conclusions on the reconstructed windfield from all available surface and WSR88D* Doppler observations are: 1) All official wind observing systems (including the WSR88D) failed in the outer eye wall region of PAKA due to power loss or sensor malfunction. One amateur wind record within a few kilometers of the Guam Automated Surface Observing System (ASOS) site was available throughout the event. 2) Some Doppler winds were available from the WSR88D Level IV archive products. These winds were digitized and were used as a background wind field with a very low relative weight. 3) The wind fields for open terrain over-land exposure were probably reasonably early, when there were many reliable surface observations (but later wind analyses have problems over portions of northern Guam due to the lack of observations). 4) Although sustained winds across extreme northern Guam may have been over 145 mph, these windspeeds are not representative of the weaker winds that occurred over the remainder of the more heavily developed areas south of Anderson AFB. 5) The duration of typhoon force winds was greater than eight hours in some of the populated regions, and more than seven hours across much of the northern two-thirds of Guam. This and the shift in wind direction likely contributed to much of the damage. Some areas received over 1.5 hours of greater than 112 mph winds. 6) Finally, the duration of typhoon-force winds likely led to the perception by Guam residents that PAKA's windspeeds were greater than what was observed. Moreover, the press reports of the very high gust at Anderson AFB would have reinforced this public perception.
The team found that the damage was not as severe as implied in press reports. One unusual feature of PAKA was the development of a double-concentric eye wall as it reached peak strength and then weakened slightly before affecting Guam and Rota.
The team's wind engineering recommendations, based on damage assessment and windfield reconstruction are: 1) Use the latest building codes and upgrade/retrofit connections, especially the walls to the foundation and roofing to walls of structures. 2) There needs to be better enforcement of good construction requirements and incentives for reconstruction, including public-private partnerships of achieving these goals. 3) Another requirement is continuous inspection, maintenance, and repair of structures. 4) Harden the lifeline systems to improve post-storm recovery efforts. 5) The government should continue supporting efforts such as the PSDA quick-response teams for acquiring post-disaster perishable data. 6) Decision-makers should question often-erroneous sensationalistic media reports, such as "new world record windspeeds of 235 mph" and consult wind engineers and meteorologists.
Several issues were raised during questions and answers from the audience. Insurance will only pay for repairs to the pre-existing condition of damaged structures. There continues to be widespread lack of enforcement of good construction practice, and few incentives to upgrade existing weak structures. Winds on the island of Rota north of Guam were much less in PAKA, and the WSR88D winds as adjusted were less than surface anemometer data. Anderson AFB was 300 feet higher than sea level and surrounding terrain and may have therefore experienced somewhat higher winds than other locations on Guam. The coastal storm surge was about 8-9 feet and didn't cause much damage, but flooding rains did. A final concern expressed is the continued development on Guam, even though it gets many "near misses" from typhoons.
*WSR88D Doppler is the same as NEXRAD Doppler (Weather Surveillance Radar--1988 Doppler).
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