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    Melissa

Enhanced Fujita Ratings Debate Thread

Hurricane Melissa currently has wind gusts exceeding 215 mph. Praying for everyone currently in the path. It's going to be devestating.

If it makes landfall at this strength who thinks the wind damage will resemble an EF5 tornado? Will entire forests be flattened and debarked? Cars and trains tossed? Ground scouring/trenching? There will certainly be a vertical wind component in the mountains too.
 
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Grand Poo Bah said:
Hurricane Melissa currently has wind gusts exceeding 215 mph. Praying for everyone currently in the path. It's going to be devestating.

If it makes landfall at this strength who thinks the wind damage will resemble an EF5 tornado? Will entire forests be flattened and debarked? Cars and trains tossed? Ground scouring/trenching? There will certainly be a vertical wind component in the mountains too.
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Certainly not scouring/trenching, as those are caused by a central vortex. Melissa is just a giant storm, and can’t drill into the ground in a way tornadoes can.
 
Grand Poo Bah said:
What do you believe is driving the "drilling" mechanism? The instantaneous nature of the winds?
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I’m obviously not qualified to say for certain, but it I had to guess if would be the force of a smaller, more compact rotating vortex causing the ground to displace, as it has more concentrated energy. As opposed to that of a linear wind event, which doesn’t have a central “point” at a given location and isn’t drilling down on a specific point.

We still don’t know why scouring and trenching happens exactly, so it’s all speculation and could be completely wrong.
 
I can’t say for certain either but I’ll throw an idea in, the pressure gradient in a tornado is A) way tighter and more sharply defined than a hurricane’s is, which leads to B) the forces a given object experiences, especially within the core, are far more extreme than those felt in a hurricane. At the most basic level, the force an object feels is equal to its mass times its acceleration, and the acceleration an object experiences is higher if the pressure gradient and forces from winds are more tightly defined, especially in a faster moving tornado. That’s also why the sledgehammer effect exists, I believe.
 
Yeah, as a kid I used to be fascinated with the idea that a landfalling Cat. 5 hurricane would be like being in a violent tornado that lasted for an hour or two (exacerbated by the fact that at the time, Andrew was THE recent point of reference for U.S. hurricane landfalls, and it was one of the few that actually did produce "tornado-like" wind damage - which I now understand was the result of an unusual combination of its intensity, the relative lack of surge in the areas that experienced the strongest winds, and the fact that it hit a lot of vulnerable structures such as mobile homes and poorly constructed frame homes).

I've come to learn that there are so many differences between the way tornado and hurricane wind fields behave, they just aren't directly comparable.
 
I really want to see the hurricane damage @buckeye05 was referring to in the Melissa thread. Not because I don't believe him, but because it sounds extremely interesting. Might have to do some digging later.

I do have pictures of a rolled car and lightly debarked trees from Andrew, and it looks like Melissa nubbed a bunch of trees as well. I think it's pretty clear much higher winds are required to sandblast trees clean the way upper echelon tornadoes do. My best guess is 245 mph gusts are the absolute minimum required to start seeing that.
 
Grand Poo Bah said:
I really want to see the hurricane damage @buckeye05 was referring to in the Melissa thread. Not because I don't believe him, but because it sounds extremely interesting. Might have to do some digging later.

I do have pictures of a rolled car and lightly debarked trees from Andrew, and it looks like Melissa nubbed a bunch of trees as well. I think it's pretty clear much higher winds are required to sandblast trees clean the way upper echelon tornadoes do. My best guess is 245 mph gusts are the absolute minimum required to start seeing that.
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Go to the Tropical subforum and click on the Significant Tropical Cyclones thread. I bumped it to the top for you. While unfortunately there are a few dead pics, pics most of the stuff being discussed is there, including lots of eyewall slabbing and debarking pics. The most unfortunate absence is what was a pic showing an anchor bolted home partially slabbed by Dorian’s eyewall. Be sure to check out the incredible debarking pics from Dorian and Andrew on pages 2 and 4. Make sure to look at the entire thread, as it will show you what eyewall mesovortices and Cat 5 eyewall winds can really do.
 
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tornado examiner said:
I saw that a few of the tornadoes on the DAT from April 27 2011 have had updates.
Added text on the track lines and readjusted tracks. Mainly the enterprise EF4 and Philadelphia EF5 having their tracks edited based on satellite imagery. Neat that reanalysis is already ongoing in any capacity.
Epic.
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1761831619926.png
huh? theres a difference? cause i dont think i notice it?
 
tornado examiner said:
I saw that a few of the tornadoes on the DAT from April 27 2011 have had updates.
Added text on the track lines and readjusted tracks. Mainly the enterprise EF4 and Philadelphia EF5 having their tracks edited based on satellite imagery. Neat that reanalysis is already ongoing in any capacity.
Click to expand...
Still waiting for those Tuscaloosa and Ringgold upgrades.
James Franco Flirt GIF

Speaking of which, my list of EF5s that day minus the actual EF5s:
  • Ringgold - EF5 201, pretty self-explanatory
  • Cullman - EF5 201, obliterated homes and other extreme damage near Ruth and Arab
  • Cordova - EF5 201, also self-explanatory, although it's more contextual
  • Tuscaloosa - EF5 205+ per what happened at the Chastain Manor, applying DOD7 for ACT
There's a few others, like Ohatchee, Flat Rock, Chilowee and GSM, which I'm more on the fence about.
 
buckeye05 said:
Go to the Tropical subforum and click on the Significant Tropical Cyclones thread. I bumped it to the top for you. While unfortunately there are a few dead pics, pics most of the stuff being discussed is there, including lots of eyewall slabbing and debarking pics. The most unfortunate absence is what was a pic showing an anchor bolted home partially slabbed by Dorian’s eyewall. Be sure to check out the incredible debarking pics from Dorian and Andrew on pages 2 and 4. Make sure to look at the entire thread, as it will show you what eyewall mesovortices and Cat 5 eyewall winds can really do.
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I will stick my nose in here at the risk of getting it punched. Yes hurricanes can do tornado-like damage,and the worst damage in both is near the center. But why the usual disparity here when the wind speeds correlate closely? The 'sledgehammer' effect' does play a part with tornadoes but we've seen slow moving tornadoes where that would be minimized, and yet there's still a big difference between the two. The vertical component of tornadoes seems to be the biggest difference to me, but let's go past that for now. So why with matching windspeeds do tornadoes do more damage than hurricanes?

Hurricane windspeeds are measures with a good degree of accuracy; I think we can trust those numbers. Tornadoes rarely get measured and when they do the accuracy of the measurement is questionable; even careful Doppler measurements are being debated. It's mostly the damages giving us estimated tornado windspeeds. Now most of those are a result of careful scientific study and experiments done in lab conditions where the exact windspeed is known and the actual type of structure is tested with equal care yet they still do not correlate well, and here's a reason for that: The lab results are wrong-they must be wrong if they do not match real-world experiences. Maybe it's the missing vertical component and maybe not but clearly we cannot trust the lab results yet that is exactly what we do when we send survey teams out to study the damage and rate the windspeeds.

There is little use in trying to refine the expected results to better match reality when the methods used to achieve the results are wrong. Rather than updating the Fujita scale maybe we should first be figuring out why our methods don't work and correct that first, otherwise we will get stuck in a loop of never-ending changes leading us back to where we started with no real progress going forward like we want. Thus my constant harpingabout the broken system being the real problem.

Just some food for thought- punch away.
 
Central Ohio Wx said:
Still waiting for those Tuscaloosa and Ringgold upgrades.
Speaking of which, my list of EF5s that day minus the actual EF5s:
  • Ringgold - EF5 201, pretty self-explanatory
  • Cullman - EF5 201, obliterated homes and other extreme damage near Ruth and Arab
  • Cordova - EF5 201, also self-explanatory, although it's more contextual
  • Tuscaloosa - EF5 205+ per what happened at the Chastain Manor, applying DOD7 for ACT
There's a few others, like Ohatchee, Flat Rock, Chilowee and GSM, which I'm more on the fence about.
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New Wren is worth strong consideration. It practically wasn't even surveyed.
 
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