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 2007.

1. small barns, farm outbuildings2. one or two family residences3. single wide mobile home4. double wide mobile home5. apartment, condo, townhouse (3 stories or less)6. motel7. masonry apartment of motel8. small retail building (fast food restaurant)9. small professional (bank, doctor’s office)10. strip mall11. large shopping mall12. large retail building13. automobile show room14. automobile service building

Damage Indicator Categories continued:

15. 1 story elementary school16. junior or senior high school17. low rise (1 – 4 story) building18. mid rise (5 – 20 story) building19. high rise (over 20 stories)20. institutional building (hospital, college)21. metal building system22. service station canopy23. warehouse24. transmission line tower25. free standing tower26. free standing pole (flag)27. hardwood tree28. 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

One or Two Family Residences

• DODs• 1• 2• 3• 4• 5• 6• 7• 8• 9• 10

DOD to Wind Speed to EF-Scale

EF-Scale Categories Wind Speed Ranges

EF0 65-85

EF1 86-110

EF2 111-135

EF3 136-165

EF4 166-200

EF5 >200

How would you rank the tornado that did this damage?

• EF 5

• Joplin, MO

• June 2011

What’s it like in an EF 4?

• CNN news report

Let’s ask this guy