The Fujita Scale (OLD!) Tornado winds are too strong to be measured. They break the instruments! Therefore, scientists use the damage caused by a tornado to rank it. What would the winds have to be to cause that kind of damage? F0 (Gale) F1 (Weak) F2 (Strong) F3 (Severe) F4 (Devastating) F5 (Incredible)

Recognizing weaknesses in the scale, in 1992 Mr. Fujita updated it to attach an estimate of the damage to the F- scale based on types of structural damage.

To add consistency to tornado ranking, a set of 28 “damage indicators” was adopted in small barns, farm outbuildings 2. one or two family residences 3. single wide mobile home 4. double wide mobile home 5. apartment, condo, townhouse (3 stories or less) 6. motel 7. masonry apartment of motel 8. small retail building (fast food restaurant) 9. small professional (bank, doctor’s office) 10. strip mall 11. large shopping mall 12. large retail building 13. automobile show room 14. automobile service building

Damage Indicator Categories continued: story elementary school 16. junior or senior high school 17. low rise (1 – 4 story) building 18. mid rise (5 – 20 story) building 19. high rise (over 20 stories) 20. institutional building (hospital, college) 21. metal building system 22. service station canopy 23. warehouse 24. transmission line tower 25. free standing tower 26. free standing pole (flag) 27. hardwood tree 28. softwood tree

Degree of Damage Each damage indicator category has a description of the typical construction for that category. The next step is to identify the Degree of Damage (DOD) that occurred in the tornado. From the DOD in that category, an estimate of wind speed is made.

One or Two Family Residences

DODs

DOD to Wind Speed to EF-Scale EF-Scale CategoriesWind Speed Ranges EF EF EF EF EF EF5>200

How would you rank the tornado that did this damage?

EF 5 Joplin, MO June 2011