Symposium on the F-Scale and Severe-Weather Damage Assessment


F-scale modification process and proposed revisions

James R. McDonald, Texas Tech University, Lubbock, TX; and K. C. Mehta and S. Mani

A process has been under way for more than a year to revise and enhance the Fujita Scale (F-Scale). Personnel at Texas Tech University undertook the effort in cooperation with users of the F-Scale, both engineers and meteorologists. A steering committee organized a forum that was attended by 25 interested parties. A process for enhancing the F-Scale was developed by forum participants. The strategy includes achieving a general consensus among users and interested parties, including the National Weather Service.

Forum participants determined a need for additional damage descriptors and a better correlation between damage and wind speeds. Another goal was to preserve the current tornado database with minimum modifications.

The correlation between tornado damage and wind speed is obtained through a process of expert elicitation, which has been successfully used in estimating earthquake parameters that cannot be measured directly. A detailed protocol is followed to assure that the collective opinions of the expert sample represents the opinions of the total population of experts on damage versus wind speed correlation. Results from the expert elicitation will be the basis for revised wind speed ranges and damage descriptions.

Proposed revisions will be presented in a effort to gain widespread consensus for the “Enhanced Fujita Scale.” The goal is to have easily identifiable damage indicators, consistent intensity ratings and a well-defined protocol for making the assessments.

extended abstract  Extended Abstract (128K)

Session 1, Modifications to the Fujita Scale
Monday, 10 February 2003, 9:15 AM-10:15 AM

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