Verification of the AFWA 3-Element Severe Weather Forecast Algorithm
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Authors
Pagliaro, Daniel E.
Subjects
Advisors
Nuss, Wendell A.
Date of Issue
2008-03
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Accurate severe thunderstorm forecasts are critical to providing sufficient leadtime to protect lives and property. The Air Force Weather Agency has developed a 3-Element Severe Weather Forecast Algorithm that when applied to model forecasts gives and outlook region for severe thunderstorms. Improvements were made in this study to enhance the algorithm's forecast skill, reduce its "false alarm" rate, and thereby increase the amount of lead-time for installation commanders to take decisive action to protect personnel and resources. This paper discusses the performance of the 3-Element Algorithm in its original form, and the adjustments made to overcome some of its limitations. The 3-Element Algorithm techniques and results of a performance evaluation are presented. Based on the amount of forecast improvement, eight configurations were retained for analysis across the entire dataset containing six severe weather cases. A new stability proxy, the Elevated Total-Totals Index, was developed and integrated into the algorithm to improve severe weather forecasts over high-elevation regions where some traditional severe weather indices cannot be accurately computed. Additionally, the horizontal gradient of convective available potential energy was studied as a new indicator to the presence of dynamic forcing. It is hoped that improvements discussed in this paper will make the 3-Element Algorithm an effective tool in the early forecasting of severe weather, increasing lead-time to safeguard lives and resources.
Type
Thesis
Description
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Organization
Naval Postgraduate School (U.S.)
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Format
xvi, 87 p. : maps ;
Citation
Distribution Statement
Approved for public release; distribution is unlimited.