It’s been more than 40 years since Ted Fujita introduced his renowned Tornado Damage Scale – the Fujita Scale. And nearly a decade has passed since top tornado scientists first collaborated with structural engineers to create the Enhanced Fujita (EF) Scale for rating tornado winds more accurately based on advances in our understanding of the variety of damage they inflict. Now, an effort is underway to tweak the EF Scale further – and the National Weather Service is looking for input from AMS meeting attendees this week.
The effort stems from the observations and analysis of recent violent tornado events: the massive tornado outbreak across the South in April 2011; the violent (EF5) Joplin, Missouri tornado of May 2011; and the Newcastle-Moore, Oklahoma EF5 tornado of May 2013. Survey teams were able to use more than two dozen “damage indicators,” such as wood-frame homes, strip malls, and schools—each further categorized by multiple “degrees of damage”—to gauge tornadic winds. But questions and even discrepancies arose among the survey teams as they scoured the wreckage of entire neighborhoods.
Oral and poster presentations throughout this week at the AMS Annual Meeting in Atlanta share information about the damage surveys, findings from reports such as the National Institute of Standards and Technology (NIST) technical investigation of the Joplin tornado and FEMA’s Mitigation Assessment Team Report on the Spring 2011 tornadoes, as well as thoughts for improving the EF-scale:
- The Joplin Tornado: Lessons Learned from the NIST Investigation (Tuesday, 9:15 a.m., Georgia Ballroom 2)
- Damage Survey and Analysis of the 20 May 2013 Newcastle-Moore, OK, EF-5 Tornado (Poster 828, Wednesday, 2:30-4 p.m., Hall C3)
- Aerial Damage Survey Analysis of the 20 May 2013 Moore Tornado (Poster 829, Wednesday, 2:30-4 p.m., Hall C3)
- Side-by-side tree and house damage in the May 2013 Moore, OK EF-5 tornado: Lessons for the Enhanced Fujita scale (Poster 831, Wednesday, 2:30-4 p.m., Hall C3)
- A related poster presentation looks at assigning EF-scale ratings to tree damage in severely damaged forests using only aerial photos.
- Photogrammetric analysis, from the ground and the air, was also used to survey the huge El Reno, Oklahoma of May 31, 2013,
- Terminal Doppler Weather Radar (TDWR) in Oklahoma City captured rare up-close velocity data of the Newcastle-Moore tornado that can be compared with survey estimates of tornado damage and intensity rankings.
All of these represent on-going thinking about the EF Scale and how to refine it.
If you’d like to get involved, NWS is hosting an open discussion of the EF Scale to acquire feedback on its strengths and deficiencies. Space is limited so sign up today.