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Severe WX April 1-2 (overnight) Severe Weather Event

Lake Martin EF4 said:
aActually, if you look through the Significant Tornadoes thread, @CAL and (especially) @TH2002 found very convincing evidence that EF5 damage was missed during the survey. New Wren 2011 is a similar story.
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I am 100% convinced that Holly Springs should have been rated EF5. In my personal opinion, after seeing the damage they found, I consider it to be one of the more egregious cases actually.
 
The CAL thing in Holly Springs was a bit overblown imo. It was underwhelming when I saw the pictures vs what he described. The slabbed structures were relatively small public restrooms and garage type structures that lacked interior walls. The contextual evidence was was quite violent at the racetrack, and potentially indicative high-end EF4, but nothing that “screamed EF5”. I just think it’s a bit hyped up, which becomes more apparent when you just look at it objectively and independent from CAL’s narrative of what happened and what the damage is representative of.
 
NickKrasz_Wx said:
One issue I notice here is that several of the anchor bolts were installed too close to the edge of the sill plate. Additionally, large portions of the home—walls, floor system, etc.—remained on the foundation. With a typical DoD-9 damage indicator, we’d expect near-total destruction of the structure and the large portions, but with most of the debris still present on or near the foundation, this was an issue we saw with Newnan (and why it should not have gotten EF4).

When anchor bolts are placed too close to the edge of the sill plate, even without visible splitting, it weakens the continuous load path. There’s less surrounding wood for the bolt to grip, which reduces its ability to resist uplift and lateral forces. This weakens the connection to the foundation and increases the likelihood of failure under tornado loads. 160 mph EF3 seems to be the right call here—I also discussed this with one of the NWS meteorologists from a different office who contributed to the survey. Also, the 150 mph DI for the home is supposed to say 160 mph, they just forgot to adjust the wind speed up after the preliminary survey.

As for the Senatobia home discussed here—using cut nails as the primary connection is a major weakness. That shouldn’t be rated at 160 mph EF3. Based on DoD-9, I’d say more in the 140–145 mph range (lower-bound).
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Honestly, I'd rather just look at it this way:

Arguments for an EF4 rating
-Home built on concrete slab
-Reasonable anchoring
-All walls down (DOD 9)
-Sufficient contextual support for a violent rating

Arguments against an EF4 rating
-Anchor bolts slightly too close to edge of sill plating

Was the anchoring on that house 100% perfect? No, but I'm sure the anchoring it did have is still a step up from the home being poorly anchored using cut nails, or unanchored entirely. That, combined with the contextual support for a violent rating just feels like going with Occam's razor imo.
 
TH2002 said:
Honestly, I'd rather just look at it this way:

Arguments for an EF4 rating
-Home built on concrete slab
-Reasonable anchoring
-All walls down (DOD 9)
-Sufficient contextual support for a violent rating

Arguments against an EF4 rating
-Anchor bolts slightly too close to edge of sill plating

Was the anchoring on that house 100% perfect? No, but I'm sure the anchoring it did have is still a step up from the home being poorly anchored using cut nails, or unanchored entirely. That, combined with the contextual support for a violent rating just feels like going with Occam's razor imo.
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Exactly. There are way more point’s in favor for an EF4 rating than EF3
 
Honestly, the main things that convince me Holly Springs was an EF5 (or at least reached that intensity) are the homes along Lamar Road and a few other rural ones that were slabbed. The damage to the racetrack was definitely violent, but I don't even think that's where it reached its peak intensity tbh.
 
It is worth noting that it is taking MEG significantly longer to upload the full survey’s for the grand junction and selmer tornado’s to the DAT.
Maybe they’re still looking at things?
 
NickKrasz_Wx said:
NWS Jackson, Mississippi assisted Memphis with these damage surveys.
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What harm would it have caused if these NWS offices would have rated it as a 170 mph EF4? The house looks like it was of at least decent construction. I am just curious and I have been studying tornado damage for 20+ years and this certainly doesn't look like a case of horrible anchoring. Maybe it was a little bit subpar but why not give it an EF4 rating? It doesn't appear to be a serious violation and I am baffled how survey teams getting overly conservative about it.
 
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Shakespeare 2016 said:
What harm would it have caused if these NWS offices would have rated it as a 170 mph EF4? The house looks like it was of at least decent construction. I am just curious and I have been studying tornado damage for 20+ years and this certainly doesn't look like a case of horrible anchoring. Maybe it was a little bit subpar but why not give it an EF4 rating? It doesn't appear to be a serious violation and I am baffled how survey teams getting overy conservative about it.
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Pretty simple explanation, really. You pointed it out yourself in the Matador thread:

"They deliberately underrate tornadoes to make people like us mad. Yes, that is what is going on."
 
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