• Welcome to TalkWeather!
    We see you lurking around TalkWeather! Take the extra step and join us today to view attachments, see less ads and maybe even join the discussion.
    CLICK TO JOIN TALKWEATHER

Enhanced Fujita Ratings Debate Thread

AJS said:
In terms of contextual damage when it comes to Marion, one can’t deny that it doesn’t signal a high end EF4 at all.
Click to expand...
I mean, at the residence in question, it slabbed the house, apparently wind rowed or "scattered" debris, and stubbed trees. I think at at least that property structural damage + context were EF4. Going by the report, anyway. And the house was built well.

I haven't seen very many pictures, though, of this tornado in general.
 
Aaron Rider said:
I mean, at the residence in question, it slabbed the house, apparently wind rowed or "scattered" debris, and stubbed trees. I think at at least that property structural damage + context were EF4. Going by the report, anyway. And the house was built well.

I haven't seen very many pictures, though, of this tornado in general.
Click to expand...
I do agree with EF4, I just don’t believe the contextual damage pointed to damage around 190 MPH.
 
Aaron Rider said:
I mean, at the residence in question, it slabbed the house, apparently wind rowed or "scattered" debris, and stubbed trees. I think at at least that property structural damage + context were EF4. Going by the report, anyway. And the house was built well.

I haven't seen very many pictures, though, of this tornado in general.
Click to expand...
 
Aaron Rider said:
I mean, at the residence in question, it slabbed the house, apparently wind rowed or "scattered" debris, and stubbed trees. I think at at least that property structural damage + context were EF4. Going by the report, anyway. And the house was built well.

I haven't seen very many pictures, though, of this tornado in general.
Click to expand...
Here's a picture I stole from Aaron Rigsby's video. The house that got the ef4 is in the top left, while the tree damage in center was also rated ef4.1751481895793.png
 
Tylertown was more violent than I initially thought.

Please understand: I am not saying this tornado deserved to be rated higher. I am just genuinely curious because the DAT description is scanty. This is from the EF4 rated damage.

Here's what the DAT says: "Well built two story home. Wood bolted to foundation. Some bolts pulled off of foundation. Found some clips but most of the damage is thrown behind the house and inaccessible."

That's ambiguous, though. Did the bolts shear or did the concrete shear out? Was the anchoring reasonable? By contrast, in my opinion anyway, the photos from Diaz seem to show a clear anchoring performance indicating the structural connections held until the bolts themselves couldn't handle the wind load (note that the washers were still present in the case of the badly sheared Diaz bolts).

The far right anchor bolt in the first picture is clearly deformed, but not as badly as Diaz. I'm guessing sill plate failure was the dominant failure mode, though? (which is less extreme than the Diaz case)

The images are too big, so here are the links

Hard to grade context from this, but it does look closer to old school F4 than F5, IMO.

Here are the 3 pictures on the DAT. Again, I just want to know if anyone knows more about why they stuck with EF4. Am I on the right track in assuming that there was some sill plate failure + lower context in the judgment? Anyway, it was definitely a very, very violent tornado.
 
AJS said:
I do agree with EF4, I just don’t believe the contextual damage pointed to damage around 190 MPH.
Click to expand...
Exactly. This is one of the rare cases where a tornado may have been overestimated. The home in Marion, Illinois sat either on pier and beam foundation or poured concrete wall foundation (likely the latter), where the sill plates were likely properly anchored to the perimeter foundation walls. The elevated floor system consisted of floor joists toe-nailed into the sill plates (evidenced by nails being ripped out of the subflooring, as well as wall bottom plates removed), with wall bottom plates straight-nailed into either the header or floor joists depending on their position on the floor system.

Although the home was swept from the floor system, that system itself remained intact and in place. The main issue with the survey was the degree of damage (DoD) applied. According to engineer and meteorologist Tim Marshall, homes swept from crawlspace or CMU foundations should be assigned a DoD-9, not a DoD-10. DoD-10 is typically reserved for slab-on-grade homes only. If we apply DoD-9 in this case, considering the construction and nearby tree damage, estimated winds around 170 mph are more appropriate.

A great comparison is the EF4 tornado in Fifty-Six, Arkansas on March 14th. A similar home built on a crawlspace was swept from its elevated floor system and properly rated as DoD-9, EF4 with 170 mph winds. For further reference, images 1 and 2 are from Marion, Illinois and images 3 and 4 are from Fifty-Six, Arkansas.

1751512157023.png
1751512148890.png
1751512016343.png
1751512244018.png
 
NickKrasz_Wx said:
Exactly. This is one of the rare cases where a tornado may have been overestimated. The home in Marion, Illinois sat either on pier and beam foundation or poured concrete wall foundation (likely the latter), where the sill plates were likely properly anchored to the perimeter foundation walls. The elevated floor system consisted of floor joists toe-nailed into the sill plates (evidenced by nails being ripped out of the subflooring, as well as wall bottom plates removed), with wall bottom plates straight-nailed into either the header or floor joists depending on their position on the floor system.

Although the home was swept from the floor system, that system itself remained intact and in place. The main issue with the survey was the degree of damage (DoD) applied. According to engineer and meteorologist Tim Marshall, homes swept from crawlspace or CMU foundations should be assigned a DoD-9, not a DoD-10. DoD-10 is typically reserved for slab-on-grade homes only. If we apply DoD-9 in this case, considering the construction and nearby tree damage, estimated winds around 170 mph are more appropriate.

A great comparison is the EF4 tornado in Fifty-Six, Arkansas on March 14th. A similar home built on a crawlspace was swept from its elevated floor system and properly rated as DoD-9, EF4 with 170 mph winds. For further reference, images 1 and 2 are from Marion, Illinois and images 3 and 4 are from Fifty-Six, Arkansas.

View attachment 44763
View attachment 44762
View attachment 44761
View attachment 44764
Click to expand...
Glad to have you back on here.

Hopefully a more welcoming experience for you this time around.
 
Finally responding to the Severe Weather 2025 Gary tornado discussion in here.

That tornado was violent. The fact it's even a debate just shows how desensitized the weather community has become to the absolute extremes of tornado strength. Seriously, imagine you live in a different country and have never heard of tornadoes, but are very familiar with powerful Typhoons. You'd see the image of that truck and your jaw would hit the floor. Hurricanes and Typhoons don't do this type of wind damage. They never have and they never will. It requires exceptionally strong force to carry a truck over the length of four football fields and mangle it beyond comprehension. The 165 mph designation is very silly, and the classification of this tornado as "strong" instead of "violent" is misleading. However, the house was a slider, so whatever I guess!..

It'd be so great if we could just go back to tornado rating brackets with huge 40 mph ranges, and then categorize them using all the available evidence again. It's exhausting having these "5-10 mph up or down" engineering debates about tornadoes that are so clearly beyond that type of specificity (by their very nature).

Edit:

And before anyone mentions the vertical wind component. If 165 mph vertical winds could lift a truck off the ground, 165 mph straight line hurricane/typhoon winds would certainly shred large boats and roll them down city streets.
 
Last edited:
NickKrasz_Wx said:
Exactly. This is one of the rare cases where a tornado may have been overestimated. The home in Marion, Illinois sat either on pier and beam foundation or poured concrete wall foundation (likely the latter), where the sill plates were likely properly anchored to the perimeter foundation walls. The elevated floor system consisted of floor joists toe-nailed into the sill plates (evidenced by nails being ripped out of the subflooring, as well as wall bottom plates removed), with wall bottom plates straight-nailed into either the header or floor joists depending on their position on the floor system.

Although the home was swept from the floor system, that system itself remained intact and in place. The main issue with the survey was the degree of damage (DoD) applied. According to engineer and meteorologist Tim Marshall, homes swept from crawlspace or CMU foundations should be assigned a DoD-9, not a DoD-10. DoD-10 is typically reserved for slab-on-grade homes only. If we apply DoD-9 in this case, considering the construction and nearby tree damage, estimated winds around 170 mph are more appropriate.

A great comparison is the EF4 tornado in Fifty-Six, Arkansas on March 14th. A similar home built on a crawlspace was swept from its elevated floor system and properly rated as DoD-9, EF4 with 170 mph winds. For further reference, images 1 and 2 are from Marion, Illinois and images 3 and 4 are from Fifty-Six, Arkansas.

View attachment 44763
View attachment 44762
View attachment 44761
View attachment 44764
Click to expand...

Exceptional that you're back. What rating would you have given Marion? Haven’t seen too much contextual or really any DI that indicates that it was a 190 MPH tornado. Violent? Certainly. Almost exceptionally violent? Maybe not the case. Would you have been more content with like a 170-175 rating? The home that got the 190 rating is usually a home that would range from 170-180 depending on which office is more liberal.
 
Brice W said:
Exceptional that you're back. What rating would you have given Marion? Haven’t seen too much contextual or really any DI that indicates that it was a 190 MPH tornado. Violent? Certainly? Almost exceptionally violent? Maybe not the case. Would you have been more content with like a 170-175 rating?
Click to expand...
From my POV, the house was toe-nailed, which is explicitly laid out by even Tim himself to be EXP resistance. If I'm being honest, that should mean ef4-200, but I guess I see the downgrade to 190?

Also, it seems from the description of the damage point that the windspeed was given more based of the trees behind it: "The extreme tree stubbing combined with the typical construction methods of the home support an estimated peak wind speed rating of 190 mph."

Screenshot 2025-07-03 at 12.33.09 AM.png
 
Brice W said:
Exceptional that you're back. What rating would you have given Marion? Haven’t seen too much contextual or really any DI that indicates that it was a 190 MPH tornado. Violent? Certainly. Almost exceptionally violent? Maybe not the case. Would you have been more content with like a 170-175 rating? The home that got the 190 rating is usually a home that would range from 170-180 depending on which office is more liberal.
Click to expand...
EF4 (170 mph) is better applicable, DoD-9 should’ve been used rather than 10. Or EF4 (180 mph) if applying the WFR DI in the revised EF scale.
 
N0mz said:
From my POV, the house was toe-nailed, which is explicitly laid out by even Tim himself to be EXP resistance. If I'm being honest, that should mean ef4-200, but I guess I see the downgrade to 190?

Also, it seems from the description of the damage point that the windspeed was given more based of the trees behind it: "The extreme tree stubbing combined with the typical construction methods of the home support an estimated peak wind speed rating of 190 mph."

View attachment 44765
Click to expand...
Even though the home is swept away and of typical construction, given it’s built on an elevated floor system, the max DoD that can be applied is 9 for homes swept off it. It has a weaker connection since the studs aren’t directly nailed to the sill plates, they’re nailed to the wall bottom plate that sits on the floor joist system. DoD-9 should’ve been applied instead, winds around 170 mph.
 
You must log in or register to reply here.
Back
Top