Strongest tornado of 2010

[Mike Kovalchick]

I have to say I dont think a longer duration of a tornado on an object will increase the severity of the damage to the object (i.e. I dont think a tornado with EF3 winds that sits over a house for a long duration will cause the damage to become EF4 damage because of the long duration). This is the example I have, and I may be off-base here so maybe the engineers and physicists can chime in. A tornado with EF3 winds that impacts a car will, for no matter how long a duration, be able to pick up and throw that car because it takes energy equal to or greater than a specific amount of energy (I have no idea what amount that is) to lift that car and toss it. It doesnt matter how long that tornado impacts that car because as long as it does not increase in intensity, it will never have the energy required to pick up and toss the car. If this doesnt make sense I can try to come up with another example of what I'm trying to explain.

Shane mentioned the Jarrell tornado and I recall reading a nice write-up in the old Storm Track magazine regarding the damage survey/F5 rating. The conclusion was definately that the longer the tornado was over a given location-the more damaged it caused. One interesting point that came out, if you have a poorly built home built next to a well built home..the tornado threw the projectiles from the destroyed home into the well built one causing much more damage than would have been normally expected. Or simply-the longer you throw projectiles at something, the more damage it would cause. True, you won't be able throw a car through the air just because of a longer duration tornado-but do expect to see a higher EF rating as a result.

 

[Dean Baron]

What I don't understand is why should we ever dismiss a tornado's stregnth because of it's forward speed or lack of it? It doesn't matter if a tornado is screaming along at 70mph and that forward speed enhances the damage on the southern flank OR if it instead sits there and grinds away for a minute. If the question is which one was more powerful with respect to the damage they are capable of (which is what we are ultimately concerned with) then the forward speed of the tornado is just a component of why one was more powerful, not a determining factor of whether or not it was more powerful.

But it is important to note the forward speed of the storm because there is a different between the raw power of a tornado that is stationary and one that moves at 60mph (Bowdle vs. YC). True, the damage produced may be the same but the reason for the damage is different.

 

[Dean Baron]

Shane mentioned the Jarrell tornado and I recall reading a nice write-up in the old Storm Track magazine regarding the damage survey/F5 rating. The conclusion was definately that the longer the tornado was over a given location-the more damaged it caused. One interesting point that came out, if you have a poorly built home built next to a well built home..the tornado threw the projectiles from the destroyed home into the well built one causing much more damage than would have been normally expected. Or simply-the longer you throw projectiles at something, the more damage it would cause. True, you won't be able throw a car through the air just because of a longer duration tornado-but do expect to see a higher EF rating as a result.

And to a degree I know what you are saying and I agree. But I still have to believe that there is a limit to the extent that a given tornado can do. By this I mean that en EF1 tornado cannot cause EF5 damage no matter how long it impacts an object.

 

[Bob Hartig]

I see that the poll results have been tallied up. Danny, thanks for getting this discussion rolling. Another utterly inconclusive but interesting and thoroughly enjoyable back-and-forth on Stormtrack! Kudos to all who contributed some well-reasoned and thought-provoking comments.

 

[Wes Carter]

But it is important to note the forward speed of the storm because there is a different between the raw power of a tornado that is stationary and one that moves at 60mph (Bowdle vs. YC). True, the damage produced may be the same but the reason for the damage is different.

You pretty much just restated my point: "If the question is which one was more powerful with respect to the damage they are capable of (which is what we are ultimately concerned with) then the forward speed of the tornado is just a component of why one was more powerful, not a determining factor of whether or not it was more powerful."

But I still have to believe that there is a limit to the extent that a given tornado can do. By this I mean that en EF1 tornado cannot cause EF5 damage no matter how long it impacts an object.

I think that our debate here is more about finer details than that. Was the Yazoo City a legitimate EF4 or was it an EF3 that was enhanced by it's forward momentum? Was the Bowdle wedge really just an EF4 or was it capable of EF5 damage but just didn't hit anything? I really don't think anyone is going to argue that an EF1 could ever cause EF5 damage with a difference in estimated wind speeds between the two classifications at least 145MPH. But the difference between an EF4 and EF5 is as little as 1MPH.

 

[Bob Hartig]

Was the Yazoo City a legitimate EF4 or was it an EF3 that was enhanced by it's forward momentum? Was the Bowdle wedge really just an EF4 or was it capable of EF5 damage but just didn't hit anything? I really don't think anyone is going to argue that an EF1 could ever cause EF5 damage with a difference in estimated wind speeds between the two classifications at least 145MPH. But the difference between an EF4 and EF5 is as little as 1MPH.

It's at this point that I think it's important to remember the oft-repeated maxim that the EF Scale is a damage rating from which wind speeds are extrapolated. Beyond the concrete damage criteria, things get abstract. Of course Yazoo City was a legitimate EF4. If it did EF4 damage, then it's an EF4. How it did the damage is a separate issue, and that's where we start splitting hairs and entering into all kinds of speculation. But the rating itself seems well established.

 

[Jeff Duda]

To add to the discussion between Dean, Mike, and Wes, consider the fact that an EF3 tornado likely has strong enough winds to at least get a car rolling/flipping. Thus, an EF3 rated tornado that persists longer and moves in such a way as to keep such a car within its circulation could "carry" a car (without video evidence, you're likely not going to know whether the car was rolled or carried in mid-air) quite a long way, whereas an EF4 or EF5 rated tornado moving at a different pace such that the same car is not in the circulation for as long might not be "carried" as far. I know the distance a vehicle is moved by a tornado has some weight as to what its rating is.

 

[Joshua Nall]

I remember driving down highway 3, which heads SW out of Yazoo City. There was severe tree damage in places for a few miles along there, all powerlines down and right in the middle of all this tree damage was a little ratty looking trailer house out in the open, that was unmoved. This was immediately to the S of Yazoo City where the tornado was supposed to have been near it's strongest. There were also some other houses along there looked to be right in the middle of the damage path with only shingles and a few boards missing. I also drove the full cross section of the damage along a major road in town... might have been hwy 16, and crossed the damage path 3 separate places S of highway 3. Yes there was EF4 damage in spots cause the survey people say so, so it gets a 4 rating, but it certainly was not what I would envision if someone said to me an EF4 tornado tore through a town. There were some well built buildings in town that were totally demolished, but it's not like that sort of damage occurred over a wide area... and I'm just going from what I saw. There were wood frame houses in the vicinity of the very severe damage that were mostly still standing.

I know it's just a misconception of what a EF3 or even 4 is... But when people hear a tornado caused EF3 damage for example, they picture a tornado with 135+ mph "sustained" winds. From what I saw this rotation could very well have been much less than that with a forward speed of 55 miles per hour with maybe some vortices which caused the more severe damage. There was certainly EF3 damage, and even 4 in spots evidently, but not what you would envision with a 1.5 mile wide EF3 tornado moving 55 mph through a town, much less an EF4. Forgive me if that is just restating what some have already said.

The folks that lived in the little trailer at the base of the hills, with tree damage for a half mile on either side of them, they think their trailer survived an EF3-4 tornado? I can remember thinking that was funny after the rating came out. Or the folks that owned the houses that only had shingles missing? I'm thinking the Bowdel storm would have eaten that little trailer had it even come near it. I don't think the two storms are comparable.

Also, maybe its another misconception, but I've always thought winds increased with height in a tornado, to some extent anyway... and in this event there was a very large area of intense rotation slamming into the higher terrain of Yazoo City at 55 mph. It's seems reasonable to me that parts of Yazoo experienced greater damage do to this higher elevation in relation to areas just to the SW. Air has mass and does act like a fluid to some extent, right... it can be said to have momentum even? I'm not saying that the terrain change had anything to do with the actual strength of the tornado, but might have played a part with the more damaging winds experienced in Yazoo City. May have had nothing to do with it, but it seems reasonable.

Sorry so lengthy... getting all my thoughts in one post

 

[Dean Baron]

I think that our debate here is more about finer details than that. Was the Yazoo City a legitimate EF4 or was it an EF3 that was enhanced by it's forward momentum? Was the Bowdle wedge really just an EF4 or was it capable of EF5 damage but just didn't hit anything? I really don't think anyone is going to argue that an EF1 could ever cause EF5 damage with a difference in estimated wind speeds between the two classifications at least 145MPH. But the difference between an EF4 and EF5 is as little as 1MPH.

And that's a good point that the difference between EF4 and EF5 (or any 2 different categories) could be as little as 1 mph. I know my example of an EF1 not causing EF5 damage is a bit extreme, but it is just one example how I believe every tornado has its limit to the damage it can create. So here's another example: Is an EF4 capable of carrying the debris from the foundation (like an EF5) if it is impacting the object long enough? OR, does it take a specific amount of energy in order to carry that debris away (i.e. no matter how long an EF4 impacts an object is it capable of achieving EF5 energy/damage?). Or is there something about the energy of an EF5 that impacts an object at any instant that seperates it from an EF4 no matter how long an EF4 impacts an object? Lots of questions I dont know the answers to so hopefully others can shed some light on them.

 

[Kevin Walters]

And that's a good point that the difference between EF4 and EF5 (or any 2 different categories) could be as little as 1 mph. I know my example of an EF1 not causing EF5 damage is a bit extreme, but it is just one example how I believe every tornado has its limit to the damage it can create. So here's another example: Is an EF4 capable of carrying the debris from the foundation (like an EF5) if it is impacting the object long enough? OR, does it take a specific amount of energy in order to carry that debris away (i.e. no matter how long an EF4 impacts an object is it capable of achieving EF5 energy/damage?). Or is there something about the energy of an EF5 that impacts an object at any instant that seperates it from an EF4 no matter how long an EF4 impacts an object? Lots of questions I dont know the answers to so hopefully others can shed some light on them.

It makes sense that an object subjected to winds of say 100mph may survive for a certain amount of time but ultimately fail at some point. A structure exposed to EF3 winds in a very slow moving tornado might exhibit damage in the EF4 range. How quickly any spot in the damage path experiences violent winds is important. Does it take a few seconds or is it instantaneous? The very rapid increase in wind speed places the greatest force on any object.

 

[Shane Adams]

The folks that lived in the little trailer at the base of the hills, with tree damage for a half mile on either side of them, they think their trailer survived an EF3-4 tornado? I can remember thinking that was funny after the rating came out. Or the folks that owned the houses that only had shingles missing? I'm thinking the Bowdel storm would have eaten that little trailer had it even come near it. I don't think the two storms are comparable.

That sounds like a multiple vortex structure. Often you'll hear of completely destroyed structures while either side the damage is minimal or even non-existent. Reading your description instantly made me think "multi-vortex tornado". While a "full" wedge tornado shape (actual windfield) would affect a greater area, the intensity of those winds would still be matched by a multiple vortex of the same F-rating..at least for a three-second gust (or whatever the criteria is).

As others have stated, tornadoes can be "measured" by the damage created, and that's where the concrete portion of the conversation ends. Beyond that it's pure speculation, and IMO, that's the most interesting part. I like to see the thoughts of people regarding how tornadoes generate their power and why winds may shift higher or lower from moment to moment. I've read some things I'd not considered before, such as the idea that tornadic winds increase with height and therefore higher-terrian areas may be more prone to the most severe winds/damage.

I believe that perhaps, to some degree, all tornadoes momentarily "max out" occasionally above their F-scale rating. One piece of evidence that might support this idea is the damage path of violent tornadoes that went through very densely-populated areas. You almost never see a constant F4-5 line throughout the damage; there will be maxes of F4-5 throughout the overall path, but it's obvious (from the damage survey at least) the overall strength was (1) a lower F-scale rating (F3 or lower) and (2) the top-end winds were sporadic at best. I also believe that, to some degree, ALL tornadoes are multiple vortex.

To wrap this thought up, I think there are instances of windspeeds in tornadoes that far exceed what science (at least to this point) can quantify as top-end.

 

[Jeff Duda]

Also, maybe its another misconception, but I've always thought winds increased with height in a tornado, to some extent anyway... and in this event there was a very large area of intense rotation slamming into the higher terrain of Yazoo City at 55 mph. It's seems reasonable to me that parts of Yazoo experienced greater damage do to this higher elevation in relation to areas just to the SW. Air has mass and does act like a fluid to some extent, right... it can be said to have momentum even? I'm not saying that the terrain change had anything to do with the actual strength of the tornado, but might have played a part with the more damaging winds experienced in Yazoo City. May have had nothing to do with it, but it seems reasonable.

I seem to recall seeing some laboratory test results or a conference paper some years ago that suggest that the maximum winds in a tornado may actually be very near ground level (the wind magnitude profile looks kind of like that of a LLJ scenario, just scaled down vertically). I could be wrong, but I think I've heard that. The best example I can find right now is from Bluestein et al. (2007), in particular, Fig. 15 (a and b).

And that's a good point that the difference between EF4 and EF5 (or any 2 different categories) could be as little as 1 mph. I know my example of an EF1 not causing EF5 damage is a bit extreme, but it is just one example how I believe every tornado has its limit to the damage it can create. So here's another example: Is an EF4 capable of carrying the debris from the foundation (like an EF5) if it is impacting the object long enough? OR, does it take a specific amount of energy in order to carry that debris away (i.e. no matter how long an EF4 impacts an object is it capable of achieving EF5 energy/damage?). Or is there something about the energy of an EF5 that impacts an object at any instant that seperates it from an EF4 no matter how long an EF4 impacts an object? Lots of questions I dont know the answers to so hopefully others can shed some light on them.

I think in some cases your argument would be right, but in other cases (like my car tossing example from a few posts ago) it would not be right. I think there are some objects/structures that require a certain amount of tornadic windspeed for the minimum threshold of damage to occur (and thus a weaker tornado, no matter how long it impacts said structure, could not cause the minimum threshold of damage), but there are many other objects that begin to be damaged starting at much lower wind speeds, but for which the amount of damage increases with either increased wind speed or increased duration of wind speed. In the latter case, unless you know the history of that object through the period of the tornado's impact on it, you would not be able to distinguish whether high speed damage for a short burst caused that damage or a slower speed damage for a longer period did.

I also believe that, to some degree, ALL tornadoes are multiple vortex.

I'm curious what you mean by that. For all I know that may end up being true. However, I have seen pressure traces through the center of or near tornadic cores which suggest there are at least two different types of tornado structure: single-cell, two-cell, and multi-cell. These also match laboratory simulations.

 

[Shane Adams]

I'm curious what you mean by that. For all I know that may end up being true. However, I have seen pressure traces through the center of or near tornadic cores which suggest there are at least two different types of tornado structure: single-cell, two-cell, and multi-cell. These also match laboratory simulations.

It's something I came up with from watching dust devils, and then (possibly incorrectly) applied to tornado formation. It seems to me, despite the fact many tornadoes appear visually to have one, singular, smooth vortex, there are just too many chaotic, turbulent motions with the overall windfield for it to truly be a stand-alone single vortex (meaning a solid wall/windfield). Part of this thinking on my part comes from watching tornado videos where there appear to be inner rings of condensation with the broader, less-violent rings on the outer edge. In my mind this display is a tell-tale sign of what's inside the smooth, single funnel we often see.

I wrote something on here or wx-chase years ago about those "inner rings" possibly having something to do with multiple vortex formation. Maybe in a situation where the turbulence is extreme, the vertical "stacked layered rings" get pushed and pulled into the horizontal, and you get the insane-looking multi-vortex structures like the MN helicopter video. Basically, a scaled down version of the process by which mesocyclones themselves form, on a microscale level.

 

[MatthewCarman]

When a Hurricane makes landfall you don't see every house in it's path fall apart soon after. Some of the houses may withstand the winds at first but the winds may weaken the building and destroy it later or debree may finish it off. The Bowdle tornado was moving very slow so instead of winds blasting a building for say 12 seconds the winds could blast that building for 22 seconds or longer thus giving the tornado a longer time period to weaken, damage or destroy the building. If I shoot a man he may not die but if I continue shooting that man soon or later he will get weak and die. It's no different with a tornado.

I remember a video of I think it was Hurricane Andrew. This family was trapped in their home and watched some of the houses around them fall apart but their house never did colapse. Andrew had very strong winds and was capable of destroying every house in it's path but it did not destroy every house. That does not make it a weak Hurricane. Andrew was far from weak. Just because the Yazoo tornado did not destroy every building in it's path does not make it weak. You also have to think that not every part of the tornado has it's strongest winds so some areas are not hit as hard as other areas.

When the Yazoo tornado did hit the town it may not have been at it's peak winds thus if it had hit the town 5 minutes early or later may it could have been at it's peak winds and would have caused more damage. It is hard to say the Yazoo tornado can't be an EF5 tornado just because it did not do alot of damage in this or that area. It can still be capable of EF5 damage it just did not produce EF5 damage when it struck those areas.

 

[Jeff Duda]

When a Hurricane makes landfall you don't see every house in it's path fall apart soon after. Some of the houses may withstand the winds at first but the winds may weaken the building and destroy it later or debree may finish it off. The Bowdle tornado was moving very slow so instead of winds blasting a building for say 12 seconds the winds could blast that building for 22 seconds or longer thus giving the tornado a longer time period to weaken, damage or destroy the building. If I shoot a man he may not die but if I continue shooting that man soon or later he will get weak and die. It's no different with a tornado.

There is a difference between the windfield of a hurricane and a tornado - that of scale, and for single structures it is significant. Remember that due to most tornados' small size (and someone else already mentioned this) that there is a lot of directional acceleration occurring with a tornado's winds over the scale of that structure, i.e., that structure will likely be impacted by winds coming from different directions at the same time. A hurricane's wind field is large enough compared to a structure that it will seem like those winds are more of the straight-line nature. This will cause damage to occur in different ways in a tornado than how it occurs in hurricanes.