Significant Tornado Events

[CheeselandSkies]

To me a slower forward speed in some ways gives it the opportunity to inflict more severe damage, i.e. ground scouring.

Yet some of the most dramatic examples of ground scouring ever surveyed were from the EF5s of 4/27/11 when they moved 60-70 MPH.

 

[CheeselandSkies]

Some more. The last two are of a very large, well-built brick funeral home that completely vanished at the east edge of Smithville.

In this picture, I believe it was once mistakenly thought that the drainage culvert (gap in the street next to the railroad tracks) had been ripped clean out of the ground/pavement by the tornado. It was later determined that the culvert had been dug up for replacement prior to the tornado.

 

[Juliett Bravo Kilo]

To me a slower forward speed in some ways gives it the opportunity to inflict more severe damage, i.e. ground scouring.

The problem with that logic is that there are tornadoes that have moved 70+ mph (such as Smithville or Hackleburg) and did extreme damage like ground scouring or sweeping away well-anchored homes in seconds. There have been tornadoes that moved even slower than Jarrell, such as the Bowdle, SD tornado which was practically stationary at times yet it didn't do any sort of ground scouring or extreme damage on par with Jarrell.

 

[Juliett Bravo Kilo]

This video of Hackleburg is pretty amazing. The motion and forwards speed on a funnel a mile wide is just incredible. Also, it's eerie how deathly quiet it gets before the roar of the tornado. I recommend viewing this with headphones on for maximum effect:

 

[skelly]

The problem with that logic is that there are tornadoes that have moved 70+ mph (such as Smithville or Hackleburg) and did extreme damage like ground scouring or sweeping away well-anchored homes in seconds. There have been tornadoes that moved even slower than Jarrell, such as the Bowdle, SD tornado which was practically stationary at times yet it didn't do any sort of ground scouring or extreme damage on par with Jarrell.

I follow you but I was agreeing with you that forward speed shouldn’t influence the “downgrading” of a storm. If that makes sense...

 

[CheeselandSkies]

This video of Hackleburg is pretty amazing. The motion and forwards speed on a funnel a mile wide is just incredible. Also, it's eerie how deathly quiet it gets before the roar of the tornado. I recommend viewing this with headphones on for maximum effect:

In my opinion that's one of the most iconic videos from the outbreak, right up there with the 33/40 skycam footage at Cullman and Tuscaloosa. Like if I were remaking Twister, that's how I'd want my (E)F5 scene to look (maybe without so many intervening trees, but otherwise...).

 

[Shakespeare2016]

Kelwood MB certainly doesn't get brought up enough, very little information online about that one but the ground damage is extremely interesting given its small size

I know did even ever get a rating. I think it may be too hard to give a tornado like this a rating. It certainly was an extremely intense tornado as you can tell by the ground scouring.

 

[Equus]

Hard to find info online about Canadian ratings pre-2000s, would imagine it would be rated very low if it stayed rural but it makes me wonder if it had Elie-like potential had it hit more than a few trees. I know it embedded a big tree branch 5 feet deep in a swamp but that's probably pretty typical.

Then again, if the Elie tornado's track was a few hundred yards different it would have went unrated and forgotten too

 

[Juliett Bravo Kilo]

I know did even ever get a rating. I think it may be too hard to give a tornado like this a rating. It certainly was an extremely intense tornado as you can tell by the ground scouring.

What's interesting about this tornado is that the ground scouring is only a few inches across!

 

[Shakespeare2016]

Here is a vid of the Elie tornado from a different perspective.

 

[Shakespeare2016]

What's interesting about this tornado is that the ground scouring is only a few inches across!

I would say in some areas at most a foot wide. However, it dug over 18 inches of topsoil in some areas.

 

[buckeye05]

What's interesting about this tornado is that the ground scouring is only a few inches across!

Maybe the best example of a “drill bit” tornado.

 

[Juliett Bravo Kilo]

One thing I've noticed is that tornadoes that occur on the Great Plains and further north, especially in the Dakotas or Canada, tend to move much more slowly then the tornadoes in Dixie Alley. Why is that?

 

[Shakespeare2016]

Even if the tiny little multiple vortices in the Kelwood, MB had winds of 300+ mph would it have been even possible for it to inflict E/F5 damage on a well-built home because it was at most a foot across?

 

[Peter Griffin]

Fast forward motion would actually increase wind speed in one if the quadrants depending on the storm motion would it not? We see a similar effect in Hurricanes.

Hurricane Joaquin in 15 was an example of it. As it was stalled in the Bahamas winds topped out at around 135mph. As soon as it started racing to the Northeast winds jumped up to 155mph even though there was no significant improvement in satellite presentation.

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[Equus]

Kelwood was rated an F0 since it hit nothing significant according to this - an unfortunate but unavoidable weakness in rating something we can only judge by its extremely inconsistent and location-dependent aftermath. No doubt we'd be looking at F3+ damage at the very least had a house just happened to be in the field where intensity was the highest.

 

[CheeselandSkies]

One thing I've noticed is that tornadoes that occur on the Great Plains and further north, especially in the Dakotas or Canada, tend to move much more slowly then the tornadoes in Dixie Alley. Why is that?

Significant tornadoes in these areas are more likely to occur in later spring/summer setups with somewhat slower mid/upper level winds. Although this isn't always the case of course.

 

[Juliett Bravo Kilo]

Fast forward motion would actually increase wind speed in one if the quadrants depending on the storm motion would it not? We see a similar effect in Hurricanes.

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I think Grazulis said something to the effect that tornadoes moving along at 60-70+ mph can hit structures hard enough that it produces a sledgehammer-like effect that makes the destruction much more thorough.

 

[Juliett Bravo Kilo]

Significant tornadoes in these areas are more likely to occur in later spring/summer setups with somewhat slower mid/upper level winds. Although this isn't always the case of course.

So are upper-level winds faster-moving in the winter and early spring? Is there a reason for that?

 

[CheeselandSkies]

So are upper-level winds faster-moving in the winter and early spring? Because that's when most of the tornado outbreaks occur in the Deep South, it seems.

Yes, that is when the very fast jet streams are more likely. They (if other factors are favorable) can also contribute to extreme deep-layer shear. This is why some of the most violent tornado outbreaks (Both "Super," Palm Sunday 1965, Tri-State, Andover '91, etc) have had very fast (>50 MPH) storm motions.