Major Severe Weather Outbreak November 17

[Ensō]

  I do not now why NWS will not budge on this tornado. The forward movement and wind rowing from this tornado was extremely incredible. Do they even realize no tornado has ever rated F5/EF5 during the month of November. Sorry if this offends anybody but it really is frustrating.

 

It's frustrating that they won't rate a tornado EF5 on the basis of wind rowing and forward speed? Okay then. If they don't rate it EF5, it's because there's no clear EF5 damage to be found. The wind rowing was indeed extensive, but that isn't a useful DI. The tornado swept dozens of homes cleanly away, but if they weren't well-built - and judging by the few photos that showed no visible anchoring whatsoever, that may well be the case - then that isn't EF5 either. And in several of the photos of homes swept away, low-lying shrubs surrounding the homes appeared to have suffered little damage, which you'd expect to see in an EF5. I certainly think they could have rated it as such (hence the 190mph high-end EF4 rating), but I saw no unambiguously EF5 damage. I can think of several other tornadoes whose ratings I disagree with much more than this one.

[tornadotony]

It's frustrating that they won't rate a tornado EF5 on the basis of wind rowing and forward speed? Okay then. If they don't rate it EF5, it's because there's no clear EF5 damage to be found. The wind rowing was indeed extensive, but that isn't a useful DI. The tornado swept dozens of homes cleanly away, but if they weren't well-built - and judging by the few photos that showed no visible anchoring whatsoever, that may well be the case - then that isn't EF5 either. And in several of the photos of homes swept away, low-lying shrubs surrounding the homes appeared to have suffered little damage, which you'd expect to see in an EF5. I certainly think they could have rated it as such (hence the 190mph high-end EF4 rating), but I saw no unambiguously EF5 damage. I can think of several other tornadoes whose ratings I disagree with much more than this one.

My initial gut reaction was toward EF5 just by the pictures, but when you look closer/over a ton of them, you begin to notice something.  It's not that the homes weren't attached well to their foundations.  On the contrary, they likely were well attached.  Why?  Because the majority of those homes still had the floorboards attached to their foundations.  Thus, they're not completely swept away, and I'm not certain DOD10 could be applied in that situation.  That initial gut reaction of mine was very strongly toward EF5, but now I've grown a lot more hesitant toward it.  If anything, it just goes to prove how hard it is to judge tornado intensity purely on pictures (which sounds a lot like something I wrote about in a US Tornadoes entry several months ago).

[blackjack123]

My initial gut reaction was toward EF5 just by the pictures, but when you look closer/over a ton of them, you begin to notice something.  It's not that the homes weren't attached well to their foundations.  On the contrary, they likely were well attached.  Why?  Because the majority of those homes still had the floorboards attached to their foundations.  Thus, they're not completely swept away, and I'm not certain DOD10 could be applied in that situation.  That initial gut reaction of mine was very strongly toward EF5, but now I've grown a lot more hesitant toward it.  If anything, it just goes to prove how hard it is to judge tornado intensity purely on pictures (which sounds a lot like something I wrote about in a US Tornadoes entry several months ago).

      In spite of the high-end EF4 rating I consider it to be one of the most violent November tornadoes ever recorded. There is only one other tornado that may have been of similar violence and it occurred on 11/24/01. I tend to wonder if it is even possible to get an April 27, 2011 outbreak or very similar during the fall/winter months. What I mean by that is where you get 2 or more EF5's and more than a half dozen EF4's.  

[SchaumburgStormer]

...that should've never been shot...

 

+100

 

  I do not now why NWS will not budge on this tornado. The forward movement and wind rowing from this tornado was extremely incredible. Do they even realize no tornado has ever rated F5/EF5 during the month of November. Sorry if this offends anybody but it really is frustrating.

 

Are we supposed to rate this an EF5 simply because it is November? That seems absurd.

 

It's frustrating that they won't rate a tornado EF5 on the basis of wind rowing and forward speed? Okay then. If they don't rate it EF5, it's because there's no clear EF5 damage to be found. The wind rowing was indeed extensive, but that isn't a useful DI. The tornado swept dozens of homes cleanly away, but if they weren't well-built - and judging by the few photos that showed no visible anchoring whatsoever, that may well be the case - then that isn't EF5 either. And in several of the photos of homes swept away, low-lying shrubs surrounding the homes appeared to have suffered little damage, which you'd expect to see in an EF5. I certainly think they could have rated it as such (hence the 190mph high-end EF4 rating), but I saw no unambiguously EF5 damage. I can think of several other tornadoes whose ratings I disagree with much more than this one.

 

As someone who walked the damage path, climbed through the debris, and evaluated these buildings; I agree with this assessment. These homes were by no means shacks, but they were standard "contractor grade" homes. Meet minimum code, and move on. No extra anchoring to the foundation, not structural brick, etc. The deliniation line between the older, well built homes located in the southwestern area of the damage zone (which had large chunks left intact) and the newer section of the subdivision (which was 100% gone) is striking.

 

Obviously each tornado is different, but i didn't notice any scouring on the ground or pavement, and as Enso stated, most schrubs were left intact. I agree with a EF4 rating.

 

 

Edit: I have photos specifically of the foundations and such, I just cant readily find them (have about 2000 photos). I will post them if/when I run across them.

[TropicalAnalystwx13]

I think this video takes the cake..

 

Link

[Buckeye05]

Yeah I really think they nailed it with the 190 MPH EF4 call. As Tony mentioned, I would bet that the remaining floors negated a higher rating. The problem with houses like this is that the walls are usually simply nailed into the the floors, creating a weakness where the walls meet the floorboards. There were probably bolts present, but it's very unlikely that they extended above the floors to properly anchor the walls. In other words, the floors were probably bolted down, but not the houses themselves. I saw damage very similar to this along Millbury Rd in Wood County, OH after the 2010 EF4.

[Buckeye05]

I think this video takes the cake..

 

Link

Man, that got my heart beating really fast. I can't even imagine how terrifying that would be.

[blackjack123]

+100

 

 

Are we supposed to rate this an EF5 simply because it is November? That seems absurd.

 

 

As someone who walked the damage path, climbed through the debris, and evaluated these buildings; I agree with this assessment. These homes were by no means shacks, but they were standard "contractor grade" homes. Meet minimum code, and move on. No extra anchoring to the foundation, not structural brick, etc. The deliniation line between the older, well built homes located in the southwestern area of the damage zone (which had large chunks left intact) and the newer section of the subdivision (which was 100% gone) is striking.

 

Obviously each tornado is different, but i didn't notice any scouring on the ground or pavement, and as Enso stated, most schrubs were left intact. I agree with a EF4 rating.

 

 

Edit: I have photos specifically of the foundations and such, I just cant readily find them (have about 2000 photos). I will post them if/when I run across them.

   Was the newer homes not built as well as the older homes I guess it is just my selfish wanting for this tornado to be rated EF5 even though it probably was not warranted. I found it striking there was very little to no tree debarking but was told there were very few trees in that area. I tend to wonder if that tornado may have been even more intense as it exited the area of damage.

[SchaumburgStormer]

Was the newer homes not built as well as the older homes I guess it is just my selfish wanting for this tornado to be rated EF5 even though it probably was not warranted. I found it striking there was very little to no tree debarking but was told there were very few trees in that area. I tend to wonder if that tornado may have been even more intense as it exited the area of damage.

The southwestern area features many large trees, but as previously mentioned, this is a much older subdivision. Saw a few homes with 4-5 foot diameter trees within the rubble in this area.

As you move northeast, newer homes equals newer trees. These 4-6 inch diameter trees stood no chance

[ct_yankee]

I think this video takes the cake..

 

Link

 

I think possibly this video conveys the experience of having a large violent tornado hit your house and neighborhood better than any other I've seen. Very intense. You really feel for them. Wow.

[michsnowfreak]

I think this video takes the cake..

 

Link

WOW. Just....wow

[IWXwx]

I think this video takes the cake..

 

Link

 

I can't believe that the guy continued to tape. Wow.

[tornadotony]

My current count from Sunday:

 

12 EF0

25 EF1

23 EF2

7 EF3

2 EF4

Total: 69

[tornadotony]

I just posted this status on my FB and I'm too lazy to rewrite:

 

69 tornadoes confirmed so far from Sunday's outbreak makes this the 3rd-most prolific fall tornado outbreak on record after 11/21-11/23/92 (95 tornadoes) and 11/23-11/24/01 (70 tornadoes). Even more remarkably, an astonishing 32 tornadoes have been given significant (EF2+) ratings, with 23 EF2s, 9 EF3s, and 2 EF4s confirmed. These 32 significant tornadoes rate as the second-highest number of significant tornadoes for a fall outbreak on record behind 11/21-11/23/92 (45 significant tornadoes). Note that, in terms of both total tornadoes and significant tornadoes within a 24-hour period, Sunday is #1 for both categories. It's likely that these numbers will still change/rise over the coming days.

[Hoosier]

IND released their map of preliminary tracks.  There's a potential cwa crosser in there with conflicting info from the 2 offices so I think I might give up on trying to figure out the Indiana count for now

 

 

[tornadotony]

BTW, my 69 number connects the Jasper and Pulaski paths and the Tippecanoe-Clinton-Carroll and Cass paths.  If there are separations there, the number with rise.  Also, the official tally for 11/21-11/23/92 is 98 tors/47 sig.  The numbers I listed were what I remember from Grazulis.  I would have to double-check (of course I don't have the supplement with me right now), but I think that's what he had.

[Hoosier]

I just posted this status on my FB and I'm too lazy to rewrite:

 

69 tornadoes confirmed so far from Sunday's outbreak makes this the 3rd-most prolific fall tornado outbreak on record after 11/21-11/23/92 (95 tornadoes) and 11/23-11/24/01 (70 tornadoes). Even more remarkably, an astonishing 32 tornadoes have been given significant (EF2+) ratings, with 23 EF2s, 9 EF3s, and 2 EF4s confirmed. These 32 significant tornadoes rate as the second-highest number of significant tornadoes for a fall outbreak on record behind 11/21-11/23/92 (45 significant tornadoes). Note that, in terms of both total tornadoes and significant tornadoes within a 24-hour period, Sunday is #1 for both categories. It's likely that these numbers will still change/rise over the coming days.

 

 

I'm more impressed with this outbreak than just about all other significant ones in this region of the country besides the really elite events like 4/11/65, 4/3/74 etc.  I think it even beats 3/2/12 if we just restrict it to the GL/OV area.  I was actually going to start a thread in the GLOV subforum to discuss the historical aspects of this outbreak.

[Hoosier]

Final numbers may change but even allowing for minor additions or subtractions, the current preliminary number of EF2+ tornadoes in Illinois is the 2nd greatest in an outbreak in the state (only exceeded by 12/18/1957).  The current number of EF2+ tornadoes in Indiana would rank 3rd highest in an outbreak in the state (behind 6/2/1990 and 4/3/1974, in that order). 

[Chicago Storm]

Re: Washington (IL) tor.

 

The question is did the national team even end up heading over there? Other than the tweet that was posted, there has been no news about it anywhere.

[tornadotony]

Re: Washington (IL) tor.

 

The question is did the national team even end up heading over there? Other than the tweet that was posted, there has been no news about it anywhere.

Idk...I'm starting to have doubts about it...though would certainly think Gilbert would be a reliable source and/or the tweet would have been retracted if not true.

[cyclone77]

.....The deliniation line between the older, well built homes located in the southwestern area of the damage zone (which had large chunks left intact) and the newer section of the subdivision (which was 100% gone) is striking.

 

 

In a case like this I have to wonder if debris loading within the tornado may have increased the damage potential as it entered the newer subdivision to the northeast.  I'm sure studies have been done, but when a violent tornado moves through a densely populated area the immense debris swirling within likely increases the damage as it goes along. 

 

Another thing I've wondered about is what effect, if any does the loading of the debris within the tornado effect the tornado itself.  From a mathematical standpoint you'd have to think that adding additional weight/object surface area to the swirling mass would have some impact on the tornado.  Obviously the tornado itself extends a considerable distance aloft, but near the surface is where I'm wondering if some of these factors weigh in.

[Ensō]

In a case like this I have to wonder if debris loading within the tornado may have increased the damage potential as it entered the newer subdivision to the northeast.  I'm sure studies have been done, but when a violent tornado moves through a densely populated area the immense debris swirling within likely increases the damage as it goes along. 

 

Another thing I've wondered about is what effect, if any does the loading of the debris within the tornado effect the tornado itself.  From a mathematical standpoint you'd have to think that adding additional weight/object surface area to the swirling mass would have some impact on the tornado.  Obviously the tornado itself extends a considerable distance aloft, but near the surface is where I'm wondering if some of these factors weigh in.

 

You'll find this paper interesting.

 

The Effects of Finescale Debris on Near-Surface Tornado Dynamics

[andyhb]

I get the nagging feeling we crank out at least one more of these before the year comes to a close.

Quite possible considering it's still early October. November almost always seems to provide some surprises, sometimes significant ones. 

 

Well we cranked out another one, and then some.

[cyclone77]

You'll find this paper interesting.

 

The Effects of Finescale Debris on Near-Surface Tornado Dynamics

 

Thanks for the link.  Looks like this digs into exactly the sort of things I was wondering about. 

[Ensō]

Thanks for the link.  Looks like this digs into exactly the sort of things I was wondering about. 

 

Yeah, it's a pretty fascinating paper. Interesting topic, and debris loading is another one of those factors that makes assessing damage so complicated. It's often a factor in structural damage (along with about a thousand other things) and it's particularly noticeable with tree damage; you'll often see much more intense debarking/denuding just downstream of debris sources.

[cyclone77]

Yeah, it's a pretty fascinating paper. Interesting topic, and debris loading is another one of those factors that makes assessing damage so complicated. It's often a factor in structural damage (along with about a thousand other things) and it's particularly noticeable with tree damage; you'll often see much more intense debarking/denuding just downstream of debris sources.

 

Yeah, from a damage standpoint the evolution of a strong/violent tornado is very intriguing.  When a tornado first enters an urban environment, the damage is primarily caused by the force of the wind, but as you progress further along the track, the damage/destruction is increasingly influenced by debris loading.  In the grand scheme of things, the amount of the damage that is left is what determines the intensity of the tornado relative to that location.  The forces that cause destruction along the path may vary from point to point based on debris loading/ambient tornado strength/multiple x-factors. 

[eyewall]

 

This is the YouTube Version of what was posted above. It looks to me they were extremely lucky, as I think the absolute worst winds just missed them (You can see this when he shows outside), and their house didn't get completely leveled to the foundation.

[mappy]

I think this video takes the cake..

 

Link

 

I couldn't imagine what they went through. In all my years of studying, couch chasing, making maps following storms... I always think I know what I would do if one was coming towards my house. But to be honest, I would be scared out of my mind. Thanks for sharing the video.

[SchaumburgStormer]

In a case like this I have to wonder if debris loading within the tornado may have increased the damage potential as it entered the newer subdivision to the northeast. I'm sure studies have been done, but when a violent tornado moves through a densely populated area the immense debris swirling within likely increases the damage as it goes along.

Another thing I've wondered about is what effect, if any does the loading of the debris within the tornado effect the tornado itself. From a mathematical standpoint you'd have to think that adding additional weight/object surface area to the swirling mass would have some impact on the tornado. Obviously the tornado itself extends a considerable distance aloft, but near the surface is where I'm wondering if some of these factors weigh in.

Honestly I never really considered that factor, as the tornado had been through a subdivision, heavily wooded area, and another smaller subdivision before it got to the area where I started my assessment. That paper is facinating.

[andyhb]

This is the YouTube Version of what was posted above. It looks to me they were extremely lucky, as I think the absolute worst winds just missed them (You can see this when he shows outside), and their house didn't get completely leveled to the foundation.

 

Saw this posted on another board.