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Severe Weather Threat 4/25-4/26, 2024 - (Thursday, Friday)

joshoctober16

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Elkhorn definitely had the tree damage to support it But I think survey teams in general had a more strict interpretation of the scale, one of which did value flat-out structural damage way higher than the surroundings.

The lead takeaway should be how bad American suburban construction is. You can get EF4 level tornadoes with 100-knot vrots and 70DBz debris balls over populated regions in a sprawling metro region, and not even see the light of day in a violent tornado rating anymore. You can argue that contextual damage should have raised the rating here, but inevitably the construction was so bad, that most of these homes were wiped out by EF2 winds.

Make no mistake though, this had some serious EF4+ damage capabilities had it hit something well-built. But as long as trends like this continue, EF4s will likely become as rare as how F/EF5s used to be.
View attachment 26090View attachment 26089View attachment 26086
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i think the confusion is more from the fact that 201 mph winds for example wouldn't event make EF5 damage.
Screenshot_2024-03-19_at_12.51.30_PM.png
when you compare damage spots with radar velocity the true wind speed needed is insane to just start doing EF2 damage.
if you were to have a radar measurement during a EF5 damage spot im pretty sure the winds will be at the 300-350+ MPH range
 

buckeye05

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Ok guys time to watch me eat crow. So after taking closer look at the violent-looking house damage in Minden, I'm gonna back-pedal on my previous stance of Minden, IA producing EF4-worthy damage. Yes, an anchor-bolted house was swept from it's poured concrete basement foundation, subfloor and all. No brainer EF4+ right? Wrong. The first clue is the lackluster contextual damage, which I initially explained away with the fact that this tornado had a pronounced multiple-vortex structure. But the most revealing thing here is the debris pattern, or in this case debris pile. I looked at more photos, and found that this house was not swept or obliterated in a violent manner whatsoever. It was left in a heap of intact walls and structural components. When you see big pieces of a house fully still intact in a debris pile, it's more indicative of a structural issue and/or a house collapsing under its own weight. That's exactly what I think happened here. The house was pushed off it's foundation, slid, and crumbled under it's own weight, which is not EF4-worthy. So how did an anchor-bolted house become a "slider"? I can't say for sure, but it definitely makes you think. Anyway, that's what I get for not being thorough and not looking at every available photo. A Guy had this one figured out from the beginning.

Foundation:
2394133


Debris Pile:
2394135
 

TH2002

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Ok guys time to watch me eat crow. So after taking closer look at the violent-looking house damage in Minden, I'm gonna back-pedal on my previous stance of Minden, IA producing EF4-worthy damage. Yes, an anchor-bolted house was swept from it's poured concrete basement foundation, subfloor and all. No brainer EF4+ right? Wrong. The first clue is the lackluster contextual damage, which I initially explained away with the fact that this tornado had a pronounced multiple-vortex structure. But the most revealing thing here is the debris pattern, or in this case debris pile. I looked at more photos, and found that this house was not swept or obliterated in a violent manner whatsoever. It was left in a heap of intact walls and structural components. When you see big pieces of a house fully still intact in a debris pile, it's more indicative of a structural issue and/or a house collapsing under its own weight. That's exactly what I think happened here. The house was pushed off it's foundation, slid, and crumbled under it's own weight, which is not EF4-worthy. So how did an anchor-bolted house become a "slider"? I can't say for sure, but it definitely makes you think. Anyway, that's what I get for not being thorough and not looking at every available photo. A Guy had this one figured out from the beginning.

Foundation:
2394133


Debris Pile:
2394135
Rotted baseplates and/or poor wall stud attachment are two likely explanations for anchor bolted sliders. Given the amount of sill plate removal here I'm thinking wood rot, just my two cents.

Anchor bolted slider in Brimfield:
brimfield-damage-home-basement-jpg.12173
 
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Ok guys time to watch me eat crow. So after taking closer look at the violent-looking house damage in Minden, I'm gonna back-pedal on my previous stance of Minden, IA producing EF4-worthy damage. Yes, an anchor-bolted house was swept from it's poured concrete basement foundation, subfloor and all. No brainer EF4+ right? Wrong. The first clue is the lackluster contextual damage, which I initially explained away with the fact that this tornado had a pronounced multiple-vortex structure. But the most revealing thing here is the debris pattern, or in this case debris pile. I looked at more photos, and found that this house was not swept or obliterated in a violent manner whatsoever. It was left in a heap of intact walls and structural components. When you see big pieces of a house fully still intact in a debris pile, it's more indicative of a structural issue and/or a house collapsing under its own weight. That's exactly what I think happened here. The house was pushed off it's foundation, slid, and crumbled under it's own weight, which is not EF4-worthy. So how did an anchor-bolted house become a "slider"? I can't say for sure, but it definitely makes you think. Anyway, that's what I get for not being thorough and not looking at every available photo. A Guy had this one figured out from the beginning.

Foundation:
2394133


Debris Pile:
2394135
Could it have been wood rot ot other parts of the house not being properly attached. If that is the case then I can see a high-end EF3 rating around 160 to 165 mph. As much as I would love it to be rated EF4 I guess I do have to look into what you are talking about by lack of contextual damage and other failures.
 

TH2002

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To give further credence to my theory that the Minden home had rotted baseplates, I zoomed in on what I'm talking about. On the left side, note how the wood splintered from itself as the home was pulled off its foundation by the tornado. On the right side, note the amount of dirt on the underside of the plating, which could be an indication that termites made the place their home. Could also be from an impact with the ground in this case though.
baseplate-zoomed.jpg

This is also something that has been taken into account in damage surveys before. Here's a daycare center that was swept away by the 2016 Ider, AL tornado; this structure was rated EF3 for the exact reason that the sill plating was rotted. You can also see some of the same 'splintering' towards the bottom of this photograph:
1024px-EF3IderAL.jpg


Now, when you see splintered sill plating, does that always mean that the plates were rotted? No, but I think that's what happened in Minden.
*also, to alleviate any confusion, the terms "sill plate" and "base plate" are interchangeable
 
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No spectacular tornado footage from me this time, but it was quite a chase.



A couple more images grabbed from the video...

Rope funnel from 130th St. south-southwest of Lorimor looking north at 7:49 PM, three minutes after the first Afton EF2 ended near this location per DMX's survey:

042624Chase00_13_21_02Still006_enhance.jpg

Lightning on US 169 as I was waiting for the RFD from the tornadic supercells to clear the highway.

042624Chase.00_19_26_22.Still007.jpg
 

Fred Gossage

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Just happened to look up this event on Wikipedia. I did not realize that this 4/25-4/26 event is now considered an outbreak sequence
Because of the lack of any real significant break in time at all between active periods, the whole stretch from April 25th or 26th as a start date, all the way through whenever you want to end this just-ended system's activity on Thursday night or Friday morning, can be considered an outbreak sequence. That Wikipedia article does need to separate 4/26 and 4/27 into separate outbreaks though. Even though they were on consecutive days, they were each caused by completely independent and separated synoptic systems doing their own things, and there was a gap in time lasting several several several hours between the tornado reports associated with the 4/26 activity and the tornado reports associated with the 4/27 activity. Unlike 4/25-4/28/2011 where there was never really a big time gap but just more or less continuous activity, there was significant separation with this one. 4/26 and 4/27 were separate events within an overall sequence.
 
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Because of the lack of any real significant break in time at all between active periods, the whole stretch from April 25th or 26th as a start date, all the way through whenever you want to end this just-ended system's activity on Thursday night or Friday morning, can be considered an outbreak sequence. That Wikipedia article does need to separate 4/26 and 4/27 into separate outbreaks though. Even though they were on consecutive days, they were each caused by completely independent and separated synoptic systems doing their own things, and there was a gap in time lasting several several several hours between the tornado reports associated with the 4/26 activity and the tornado reports associated with the 4/27 activity. Unlike 4/25-4/28/2011 where there was never really a big time gap but just more or less continuous activity, there was significant separation with this one. 4/26 and 4/27 were separate events within an overall sequence.

I think Wikipedia categorized this year's event as an "outbreak sequence" instead of simply an "outbreak" specifically so that they could group them into one article despite the bolded.
 
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