Tornado Size/Shape and F-rating. Any coincidence?

[Kevin Bowman]

Isn't the Fujita scale variable for any given tornado? I often hear that a particular storm produced an F-3 or F-5, but I would think a tornado starts out at F0 and progresses up the scale and possibly regresses, or varies in strength over time and distance. I guess what I'm trying to ask is if severity of a storm, or the Fujita rating can vary depending on location? If this is the case, then we can't necessairly get the big picture if investigators only base their ratings on the most heavily damaged areas/neighborhoods.

Yes May 3rd 99 would be a good example of this, from all reports there was a monster tornado just to the NW of OKC on that day but didnt get a lot of attention due to the Moore F5. I think it was the one that moved through logan country but im not positive. it stayed over mainly open land and was rated at a F4

Also remember it only takes one house for a tornado to be rated at F5, i remember seeing a aerial view with labels on all the houses and its F scale damage, it was pretty cool

 

[Greg Stumpf]

Also remember it only takes one house for a tornado to be rated at F5, i remember seeing a aerial view with labels on all the houses and its F scale damage, it was pretty cool

That image was created by me, with the help of Tim Marshall's house-by-house assessment, and is located in this paper as Fig. 11:

Speheger, D. A., C.A. Doswell III, and G. J. Stumpf, 2002: The tornadoes of 3 May 1999: event verification in central Oklahoma and related issues. Wea. Forecasting, 17, 362-381.

g

 

[Greg Campbell]

"suggests that you can have a mile wide F0 wedge"

What happens if it only travels over open, barren terrain? No damage. No damage = F0 regardless of wind speeds...

Yea, guys. I appreciate the distiction and misspoke when saying "F0." I was thinking in terms of 'weak tornado,' not literal F ratings.

Putting aside damage based F ratings; is there enough photometric, high resolution doppler, or other data to correlate funnel size vs. wing speed?

Also, a single suction vortex embedded in a weak storm could produce transient winds well out of proportion to the storm's overall strength. Assuming we come up with some manner of instrumentation to directly measure wind speeds, would a storm be rated by average, sustained, or peak winds, or somthing else altogeher? I'm asuming that Tornado science is still too young to have worked out issues like this.

-Greg

 

[Greg Stumpf]

I've personally surveyed a couple of large tornadoes (> 1/2 mile wide) that went through heavily populated or vegetated areas, with max damage high end F1, one with small pockets of F2.

And there are numerous examples of narrow strong-to-violent tornadoes as well (e.g., Mulvane '04, Union City '73).

Size and strength are not always correlated, but there is some correlated. *Generally*, larger tornadoes are stronger, but it is not always the case.