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Enhanced Fujita Ratings Debate Thread

St. Louis was definitely pushing it, and quite a bit outside the box. It did do $1.7 billion in damage though. That's a lot of damage. Some might even call it a whole four of damage. Hence EF4.
Friendly word of advice: do not, ever, give a tornado an EF4 (or an EF anything) rating based solely off of monetary costs. Tornadoes are only rated using damage intensity and (preferably) windspeed.
 
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The vegetation and ground scouring reminded me of tornadoes like El Reno 2011 and Moore 2013 but probably not quite as intense.
I wouldn’t say it was near the level of those two, but the things I saw along Gove County Rd Aa were truly incredible, and evidence of extreme wind velocities were quite prevalent. The harvested corn stalks from the field to the southwest literally being speared into the ditch, the smaller blades of grass embedded into the road, and then obviously the scouring to the healthy vegetation on either side of that road was remarkable. Another thing that really stuck out to me was just how defined the centerline and rowing of scoured vegetation was in that field, alongside the clumping of debris and the smaller trenches dug by multiple vortices really screamed “violent tornado” to me at least. I haven’t emailed the pictures to NWSGoodland as I thought they weren’t going to be much help, but I probably will either way at some point.

I’ve also never posted this before, but there was this mangled object that came from the farm visible in the distance of the photo that I was unable to identify. You can see it was pretty much packed with corn husks and plastered in mud.
206AD014-E36F-4F4C-94E4-686FB3457DF8.jpeg
 
Friendly word of advice: do not, ever, rate a tornado solely off monetary costs. Tornadoes are only rated using damage intensity and (preferably) windspeed.
That's why I said it was outside the box! And I wasn't rating solely off the monetary cost. There was also a small area of intense damage with severely damaged/destroyed masonry buildings, plus a destroyed strip mall in the same area. If we're talking about a damage scale, maybe it's not so wrong to consider all facets of damage? It'd be an especially interesting way of thinking if estimating the total kinetic output of a tornado ever became the goal. Is there a world where a damage scale rates mile-wide tornadoes with F3 winds the same as a a 300-yard-wide tornado with F5 winds? It's possible. It really depends on the purpose of the data, and what we're trying to derive from these measurements. As of right now we're literally deriving nothing from them. Not damage, energy, or wind speed. It's useless, frustrating, and impossible to study.

I'm not going to argue in favor of an EF4 rating for St. Louis, though. Just having some fun and throwing ideas around.
 
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I haven’t emailed the pictures to NWSGoodland as I thought they weren’t going to be much help, but I probably will either way at some point.

View attachment 44498

I really really think you should. I'm also willing to if you're busy.

If @NickKrasz_Wx has shown us anything, it's that a lot of offices are open to new information, and some have even responded enthusiastically enough to change their past ratings. I'm realizing we could really channel this community's energy and passion into something productive if enough people wanted to, or agreed on how to best go about it.
 
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I don't even know where to begin on figuring that out...

@TH2002 @buckeye05 @pohnpei @A Guy @Aaron Rider? Any ideas?

Honestly? Marion is probably the best answer. The structural integrity wasn’t there for a clear cut EF4 rating imo, let alone a high-end one, as the walls weren’t anchored with bolts. The tree damage and debris pattern seem to have been used as a partial basis for the violent rating, even though it wasn’t that crazy in terms of contextual evidence. Idk.

The difficulty in finding an example of a contextual based upgrade shows the problem regarding the bias that surrounds use of context by the NWS. They’re generally super eager to use it to downgrade, but extremely dismissive of it when it could be used to upgrade. That double standard will obviously skew survey results in a certain direction, and it doesn’t take a genius to see why that’s a problem.

Ps: one of those pics under Morganfield you posted is from Beauregard 2019.
 
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Honestly? Marion is probably the best answer. The structural integrity wasn’t there for a clear cut EF4 rating imo, let alone a high-end one, as the walls weren’t anchored with bolts. The tree damage and debris pattern seem to have been used as a partial basis for the violent rating, even though it wasn’t that crazy in terms of contextual evidence.

Ps: one of those pics under Morganfield you posted is from Beauregard 2019.

I was scrolling through the mid may severe weather thread earlier today to find pics for my list and ran across these.

1750812644642.png

One of the reasons for the high rating is the walls were toe-nailed. This drastically increases the sheer resistance of the walls, and is considered "well-engineered" for houses with subfloor. This was also analyzed and confirmed by structural engineers.

1750812735798.png

Another reason for the high rating is the walls appear to be hand nailed with 16D nails, which also increases sheer resistance (compared to potentially over-driven and thinner nailgun nails) . According to @Sawmaster these nails provide about as much resistance as toe-nailing by itself. Both these factors combined is what gave them the confidence for a much higher rating. Hope that clears things up. As far as engineering for this type of home it was about the best it could be. Clips would have also raised the overall wind resistance, but maybe not as much in the shear department? idk. I'm sure if it had clips we'd be talking about a very legitimate EF5 candidate.
 
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The before and after pic really gives a good indication of how badly the trees were mangled as well.

1750814044715.png1750814019950.png

There's also allegedly a rule that EF4 structural damage is needed to even consider EF4 tree damage, at least in some offices.

This explanation makes a ton of sense for why we never see EF4 tree damage by itself. I'm still wondering about the last time atypical indicators ( non-EF scale DIs) were used for an upgrade.
 
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I wouldn’t say it was near the level of those two, but the things I saw along Gove County Rd Aa were truly incredible, and evidence of extreme wind velocities were quite prevalent. The harvested corn stalks from the field to the southwest literally being speared into the ditch, the smaller blades of grass embedded into the road, and then obviously the scouring to the healthy vegetation on either side of that road was remarkable. Another thing that really stuck out to me was just how defined the centerline and rowing of scoured vegetation was in that field, alongside the clumping of debris and the smaller trenches dug by multiple vortices really screamed “violent tornado” to me at least. I haven’t emailed the pictures to NWSGoodland as I thought they weren’t going to be much help, but I probably will either way at some point.

I’ve also never posted this before, but there was this mangled object that came from the farm visible in the distance of the photo that I was unable to identify. You can see it was pretty much packed with corn husks and plastered in mud.
View attachment 44498
It wasn’t quite at that level, but honestly, it’s pretty damn close to that level. Probably a notch below. If the tornado had hit Grinnell at peak strength, I genuinely think it could’ve produced EF5 damage.
 
Speaking of strongest tornadoes: I've made the first change to my own list since originally posting it. Matador and the Bakersfield Valley/Stratton combo have swapped places. Matador is now #5, and the Bakersfield Valley/Stratton combo is now a tie for #4. Matador's slow movement speed, the larger number of mesquites vaporized in Bakersfield, and of course the oil tanks being rolled 3 miles uphill - along with Stratton's extraordinary vehicle damage - all ensured the placement change.
 
I was scrolling through the mid may severe weather thread earlier today to find pics for my list and ran across these.

View attachment 44501

One of the reasons for the high rating is the walls were toe-nailed. This drastically increases the sheer resistance of the walls, and is considered "well-engineered" for houses with subfloor. This was also analyzed and confirmed by structural engineers.

View attachment 44502

Another reason for the high rating is the walls appear to be hand nailed with 16D nails, which also increases sheer resistance (compared to potentially over-driven and thinner nailgun nails) . According to @Sawmaster these nails provide about as much resistance as toe-nailing by itself. Both these factors combined is what gave them the confidence for a much higher rating. Hope that clears things up. As far as engineering for this type of home it was about the best it could be. Clips would have also raised the overall wind resistance, but maybe not as much in the shear department? idk. I'm sure if it had clips we'd be talking about a very legitimate EF5 candidate.
This is great info. I know you mentioned this earlier as a possibility, but I had no idea this was actually confirmed, so this changes things. More impressive than I initially gave it credit for. I can’t really call it a contextual upgrade given this information.
 
This is great info. I know you mentioned this earlier as a possibility, but I had no idea this was actually confirmed, so this changes things. More impressive than I initially gave it credit for. I can’t really call it a contextual upgrade given this information.
Happy to contribute! I thought I saw some comments from last year referencing a study that looked into the wind resistance of older well-built houses. I couldn't find the link anywhere, though. Do you recall anything about it? I'd be interested in reading it. Nail type, Plywood vs. OSB, and better lumber all apparently increase the frame's strength and wind resistance.
 
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