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The Forward Speed Of A Tornado (1 Viewer)

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I have read several comments on this site how the forward speed of a tornado may be taken into account when determining the rating for a tornado. Like for instance a very slow moving violent tornado may exacerbate the extreme damage to a certain extent. I am going to list some infamous events based on how long it took for a tornado to pass over a certain area based on width, forward speed, and duration of time over a certain area.

1. Andover, KS 1991, Width...1/3 mile-wide, Forward Speed...40 mph, Duration Of Time Over A Certain Area...29 Seconds.
2. Jarrell, TX 1997, Width...3/4 mile-wide, Forward Speed...10 mph, Duration Of Time Over A Certain Area...4 Minutes 30 Seconds.
3. Greensburg, KS 2007, Width...1.7 miles-wide, Forward Speed...28 mph, Duration Of Time Over A Certain Area...3 Minutes 38 Seconds.
4. Bridge Creek-Moore, OKC 1999, Width...1 mile-wide, Forward Speed...30 mph, Duration Of Time Over A Certain Area...2 Minutes.
5. Westminster, TX 2006, Width...1/6 mile-wide, Forward Speed...12 mph, Duration Of Time Over A Certain Area...50 Seconds.
6. Smithville, MS 2011, Width...3/4 mile-wide, Forward Speed...70 mph, Duration Of Time Over A Certain Area...38 Seconds.

This is just to name a few and these are estimates and not set in stone. Here is a calculator I used to figure out my estimates.

 

TH2002

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I think in the case of Jarrell the forward speed did exacerbate the severity of the damage to an extent, but because of its practically unparalleled contextual damage in Double Creek, I am very confident it still contained F5 winds.
 

Tennie

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I think in the case of Jarrell the forward speed did exacerbate the severity of the damage to an extent, but because of its practically unparalleled contextual damage in Double Creek, I am very confident it still contained F5 winds.

I wouldn't be surprised to learn that the only type of above-ground structure that could survive a Jarrell-esque scenario (i.e. long-duration exposure to very high-speed winds loaded with sand/gravel/other debris) would be some kind of specially-designed bunker or thereabouts!:eek:
 

TH2002

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I wouldn't be surprised to learn that the only type of above-ground structure that could survive a Jarrell-esque scenario (i.e. long-duration exposure to very high-speed winds loaded with sand/gravel/other debris) would be some kind of specially-designed bunker or thereabouts!:eek:
If a structure could survive a direct hit from a tornado like Jarrell it could probably survive just about anything. Even taking into consideration its slow movement I would not be surprised if it had winds in excess of 320 MPH.
 

Tennie

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If a structure could survive a direct hit from a tornado like Jarrell it could probably survive just about anything. Even taking into consideration its slow movement I would not be surprised if it had winds in excess of 320 MPH.

Which makes it all the more unfortunate that there were no mobile radars in the vicinity to measure the wind speeds within the 5/27/1997 tornadoes. That could've at least filled in some of the blanks we still have over that event.
 

Austin Dawg

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I have read several comments on this site how the forward speed of a tornado may be taken into account when determining the rating for a tornado. Like for instance a very slow moving violent tornado may exacerbate the extreme damage to a certain extent. I am going to list some infamous events based on how long it took for a tornado to pass over a certain area based on width, forward speed, and duration of time over a certain area.

1. Andover, KS 1991, Width...1/3 mile-wide, Forward Speed...40 mph, Duration Of Time Over A Certain Area...29 Seconds.
2. Jarrell, TX 1997, Width...3/4 mile-wide, Forward Speed...10 mph, Duration Of Time Over A Certain Area...4 Minutes 30 Seconds.
3. Greensburg, KS 2007, Width...1.7 miles-wide, Forward Speed...28 mph, Duration Of Time Over A Certain Area...3 Minutes 38 Seconds.
4. Bridge Creek-Moore, OKC 1999, Width...1 mile-wide, Forward Speed...30 mph, Duration Of Time Over A Certain Area...2 Minutes.
5. Westminster, TX 2006, Width...1/6 mile-wide, Forward Speed...12 mph, Duration Of Time Over A Certain Area...50 Seconds.
6. Smithville, MS 2011, Width...3/4 mile-wide, Forward Speed...70 mph, Duration Of Time Over A Certain Area...38 Seconds.

This is just to name a few and these are estimates and not set in stone. Here is a calculator I used to figure out my estimates.



10 Seconds of Terror
 

TH2002

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I tend to believe despite the forward speed of a tornado that F5/EF5 damage usually happens in a matter of seconds. Watching the vid from Elie proves the F5 damage happened in a matter of seconds and not minutes.
Which is especially true for multiple-vortex tornadoes. Many people don't realize that tornadoes are officially measured by the width of the EF0 damage contour.
 

A Guy

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Reminds me that (mainly as a distraction from boredom and depression) last year I trawled through Storm Data and other reports and created a big spreadsheet of violent and/or long-tracked tornadoes by average speed (length/duration), though a lot of the older data is rounded to the nearest five minutes which can really throw things out,

After 340-odd entries I was quite surprised at what the fastest ended up being.
 

Tennie

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Reminds me that (mainly as a distraction from boredom and depression) last year I trawled through Storm Data and other reports and created a big spreadsheet of violent and/or long-tracked tornadoes by average speed (length/duration), though a lot of the older data is rounded to the nearest five minutes which can really throw things out,

After 340-odd entries I was quite surprised at what the fastest ended up being.

Alright, you've piqued my interest. What was the fastest tornado you've found according to your spreadsheet, and what was its forward speed?
 

A Guy

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Alright, you've piqued my interest. What was the fastest tornado you've found according to your spreadsheet, and what was its forward speed?
Harrisburg 2012, 71.2 mph (26.09 miles, 22 minutes). I was expecting it to be something from one of the major Southern outbreaks, not a relatively small one in IL. Of course there could be some error, thirty seconds would knock it off. In comparison the Smithville tornado comes out to 54.6 mph average. The fastest on April 27 was actually the Bridgeport tornado, a remarkable 69.8 mph.
 
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Tennie

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Here's a pretty good video showing what is likely the fastest forward speed of a tornado that has ever been measured:


It's a pretty fascinating video, but for those who want/need a "too long; didn't watch" summary, here's the the fastest forward speed for a tornado ever measured (so far, anyway):

Toward the end of its life span, the tornado that struck Pilger, Nebraska, on June 16, 2014, accelerated from a relatively sedate speed of around 20-30 mph as it approached near the developing Wakefield tornado, peaking out at an incredible 94.6 mph (152 km/h) over a period of just over five seconds before slowing down afterward; by the time the Pilger tornado dissipated about a half-minute later, it had slowed down to just below 50 mph.

Now, this was "merely" the peak forward speed as measured over a given segment of a tornado's lifespan, as opposed to average forward speed from beginning to end, but it still shows that rapid accelerations and decelerations of a tornado's forward speed are still something to watch out for, particularly where safety is concerned.
 
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