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Enhanced Fujita Ratings Debate Thread

Grand Poo Bah said:
Livestream of Fox Weather for anyone interested

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one thing i notice with each time tim talks about the next ef scale , he seems so proud and obssesed with the irrigation system.

what i found to be new good di is
1:its common enough and not rare (irrigation at least has this part)
2:the typical resistance is able to go at or above 150+ mph (irrigation system fails at this)

1759809082741.png

other then the whole slight backseat driver thing , the interview wasn't too bad.
 
Is there anything that could be done with Greenfield? We all know that was clearly an EF5, but did it toss any multi-ton objects? Could cars be used? I sort of take issue with capping the vehicle scale at 165, but I also understand why given examples like Deer Creek-Pasadena. Then again, who’s to say an isolated violent sub-vortex didn’t rip through that school parking lot? But also, were those vehicles left mangled by the horizontal distance they were thrown, or were they just lofted high into the air by a tight sub-vortex that had unusually intense vertical velocity?

The contradictory and complex nature of tornado damage, especially when vehicles are involved, can be hard to make sense of at times.
 
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Also, not that my opinion really matters, but when discussing ratings, I’m changing my stance on what qualifies as actual EF5 damage (as in actually deserving the rating) based on the Enderlin upgrade. I will include object lofting/throwing as genuine basis for an upgrade from now on and retroactively.

For example, remember when I said Mayfield’s high-end EF4 rating was appropriate? No longer the case.
 
buckeye05 said:
Also, not that my opinion really matters, but when discussing ratings, I’m changing my stance on what qualifies as actual EF5 damage (as in actually deserving the rating) based on the Enderlin upgrade. I will include object lofting/throwing as genuine basis for an upgrade from now on and retroactively.

For example, remember when I said Mayfield’s high-end EF4 rating was appropriate? No longer the case.
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Makes me think that tornadoes that turn vehicles into "scrap metal" (i.e. Capitol, Gary) could get upgrades on that element alone.
 
buckeye05 said:
Also, not that my opinion really matters, but when discussing ratings, I’m changing my stance on what qualifies as actual EF5 damage (as in actually deserving the rating) based on the Enderlin upgrade. I will include object lofting/throwing as genuine basis for an upgrade from now on and retroactively.

For example, remember when I said Mayfield’s high-end EF4 rating was appropriate? No longer the case.
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I’ve always thought the train derailment damage in Barnsley to begin with was quite underrated. On the dat, they mentioned the car was empty, but i’d imagine even an empty car would still take quite a significant amount of force to not only derail, but loft it a considerable distance.

The damage was rated EF2.
 
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Ozonelayer said:
Assuming its empty, lets do the calculations.
Using some quick geolocating, the hill is an approxamite 15 degree angle. Now for the math. (Using bold cause its easier to see)

Train car dimensions:
Length L = 60.1 ft ≈ 18.31 m
Width W = 10.8 ft ≈ 3.29 m
Height H = 10.5 ft ≈ 3.20 m
Mass m = 63,600 lbs ≈ 28,850 kg
Position: 40 m up a 15° slope
Car shape: approximate cylinder (frontal area roughly circular when facing wind)


Step 1: Estimate Frontal Area
A ≈ H × W = 3.20 × 3.29 ≈ 10.53 m²


Step 2: Estimate Wind Force
F_wind = 0.5 × ρ × C_d × A × v²
ρ = 1.225 kg/m³, C_d ≈ 1.2, A = 10.53 m²
F_wind ≈ 0.5 × 1.225 × 1.2 × 10.53 × v² ≈ 7.74 v² [N]


Step 3: Determine Resistive Force (Static Friction + Grade)
Rolling resistance: F_rr = μ_rr × m × g × cosθ
μ_rr ≈ 0.002, g = 9.81 m/s², θ = 15°
F_rr ≈ 0.002 × 28,850 × 9.81 × cos15° ≈ 546.7 N


Grade resistance: F_grade = m × g × sinθ
F_grade ≈ 28,850 × 9.81 × sin15° ≈ 73,300 N


Total resistive force: F_resist = F_rr + F_grade ≈ 546.7 + 73,300 ≈ 73,850 N


Step 4: Solve for Wind Speed
Set F_wind = F_resist to just start moving:
7.74 v² = 73,850
v² ≈ 73,850 / 7.74 ≈ 9,542
v ≈ 97.7 m/s ≈ 219 mph ≈ 352 km/h

So unless I am wrong (I could very well be. I'm still learning how to calculate windspeed), It would mean the Train Car had to have been exposed to ~220 MPH winds at minimum
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After checking my calculation, I can indeed confirm that my math is correct. I believe we have an instance of clear cut EF-5 damage from the Mayfield tornado.
 
buckeye05 said:
Is there anything that could be done with Greenfield? We all know that was clearly an EF5, but did it toss any multi-ton objects? Could cars be used? I sort of take issue with capping the vehicle scale at 165, but I also understand why given examples like Deer Creek-Pasadena. Then again, who’s to say an isolated violent sub-vortex didn’t rip through that school parking lot? But also, were those vehicles left mangled by the horizontal distance they were thrown, or were they just lofted high into the air by a tight sub-vortex that had unusually intense vertical velocity?

The contradictory and complex nature of tornado damage, especially when vehicles are involved, can be hard to make sense of at times.
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I think Greenfield’s concrete parking stop throws should be re-evaluated, at the very least, regardless on whether or not it results in an EF5 rating. Even if they were broken, I’ve seen calculations online that point to low level winds requiring >200 mph for them to be lofted. I believe Ethan Moriarty also supports an EF5 rating for Greenfield based on that feat, and it’s even supported by precedent due to Joplin’s EF5 rating (Iowa State wind engineer Partha Sarkar concluded this, I believe).
 
Grand Poo Bah said:
It's absolutely mind boggling to me that there have only been 3 officially rated EF4s this year. Talk about a total misrepresentation of the carnage we've seen from multiple outbreaks.
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Sorry if I'm misinterpreting this, but there has been 5 EF-4s and an EF-5 this year (Officially.) Not 3.

Enderlin, ND (EF-5)
London-Somerset, KY (EF-4)
Marion-Ceral Springs, IL (EF-4)
Tylertown, MS (EF-4)
Diaz, AR (EF-4)
Fifty-Six, AR (EF-4)

A long with that, there has been a few EF-3s that could have been EF-4s.

Lake City, AR
Selmer, TN
Bakersfield, MO
Gary, SD
 
Ozonelayer said:
This is all so surreal to me. I still am having a hard time believing this.

If they do re-evaluate tornadoes. I hope that Matador, Mayfield, and Bassfield are all atleast upgraded. Those ones are recent and I can see them being upgraded atleast by one category.
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Agreed, but unfortunately I’m not sure there’s anything from Bassfield that can be calculated using the approach used in Enderlin. I was mistaken about debarking being used as a direct EF5 indicator in the upgrade, and the tree damage in Bassfield is already rated at EF4.

Only thing I can think of that could maybe be calculated in Matador would be the parking bollards, but those were probably struck by large debris or even a vehicle rather than just 100% wind. I do think there’s enough for a debarking based upgrade there, but I doubt they’d ever consider going with EF5 based on that.
 
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