May 24 Plains/MW Severe Threat

[AtticaFanatica]

Why so secretive? We're talking tornadoes, not national security.

I think the parties involved prefer to make sure there are no issues before going "public" with anything about radar observations. Unfortunately, that tends to lead to rumors, which are often inaccurate.

[shaggy]

It amazes me how fast these storms last week intensified. We saw it with the Joplin tornado when it went from a small thin width tornado to a monster and in this video the oklahoma tornadoes sort of did the same thing.

[shaggy]

close call

[Ian]

It amazes me how fast these storms last week intensified. We saw it with the Joplin tornado when it went from a small thin width tornado to a monster and in this video the oklahoma tornadoes sort of did the same thing.

im sure a big part of it is the proliferation of video catching things not widely noticed prior. at some point almost every daylight tornado may be recorded.

[shaggy]

im sure a big part of it is the proliferation of video catching things not widely noticed prior. at some point almost every daylight tornado may be recorded.

Yeah I guess that makes sense. Now with the phones with video capacity we are seeing even more videos and people taking bigger risks and this will lead to previously unseen aspects of tornadoes.

This guy was 20 seconds away from getting hammered.

[Hoosier]

Some random trivia as we await ratings from Norman. IF all three potentially EF5 tornadoes receive EF5 designation, then Oklahoma will join Indiana as the only state to be struck by 3 EF5 tornadoes on the same day, which occurred in Indiana on 4/3/74. Additionally, 5/24/11 would go down as only the third date in recorded history with three tornadoes receiving EF5 designation, the other two being 4/3/74 and 4/27/11.

Didn't Alabama have 3 on 4/3/74? Are you using Grazulis ratings?

[blackjack123]

yeah, that post was a product of me failing to read thoroughly, not you posting misinformation. My apologies.

Thats ok it happens sometimes.

[downeastnc]

During the March 1984 carolina outbreak we had an F4 pass within 4-5 miles of my house. I was 9 at the time and I remember my parents freaking out when they went outside and could hear the tornado. So yes I believe it is certainly plausible that a tornadoes of such strong wind speeds can be heard for longer distances.

I also experienced this when I went through the eye of hurricane Bertha in 1996. As the eye was moving overhead we could start to hear the rumble of the winds coming on the back side for a solid 5+ minutes as the hurricane force winds were coming closer. It was just an ever growing loud rumble.

Actually it was more like 2-2.5 miles ( according to google earth ) as the crow flies from our house not 4-5 miles. Regardless the sound was very loud like a long rumble of thunder that lasted for quite awhile.

As for upgrades it seems like there should be more EF5's since it goes from 200 and up, basically every F4 in the past would today be a EF5 if they happened today, if March 28th 84 happened today NC would have had 2-3 EF5's.

Outbreaks like the Super Outbreak in 74 had 24 F4's which if added to the 5 F5's means had that happened today and the storms got the same ratings would have meant there were 30 EF5's in one outbreak.

[jpeters3]

Actually it was more like 2-2.5 miles ( according to google earth ) as the crow flies from our house not 4-5 miles. Regardless the sound was very loud like a long rumble of thunder that lasted for quite awhile.

As for upgrades it seems like there should be more EF5's since it goes from 200 and up, basically every F4 in the past would today be a EF5 if they happened today, if March 28th 84 happened today NC would have had 2-3 EF5's.

Outbreaks like the Super Outbreak in 74 had 24 F4's which if added to the 5 F5's means had that happened today and the storms got the same ratings would have meant there were 30 EF5's in one outbreak.

F4=EF4

F5=EF5

i.e. an F4 ten years ago would still be rated EF-4 today. If anything, damage assessment has become more stringent due to better awareness of the construction quality of a structure on the DOD.

[natecast]

F4=EF4

F5=EF5

i.e. an F4 ten years ago would still be rated EF-4 today. If anything, damage assessment has become more stringent due to better awareness of the construction quality of a structure on the DOD.

Exactly. The EF scale is a damage scale, not a wind speed scale. It still takes the same type of damage to rate a tornado an EF-5 as it used to be for an F-5.

[blackjack123]

Didn't Alabama have 3 on 4/3/74? Are you using Grazulis ratings?

How many F5 tornadoes were there that day? Some sources say 6 and others say 7. Even SPC lists 7 but I always thought it was 6.

[thewxmann]

How many F5 tornadoes were there that day? Some sources say 6 and others say 7. Even SPC lists 7 but I always thought it was 6.

Depends on if you consider Tanner #2 an F5.

[downeastnc]

Exactly. The EF scale is a damage scale, not a wind speed scale. It still takes the same type of damage to rate a tornado an EF-5 as it used to be for an F-5.

I understand that however in order for a tornado to get a F4 rating the damage had to be consistant with winds over 207 mph. Assuming that the damage surveys conducted in the past where accurate and all past F4's had winds over 200 mph wouldnt it figure that had they all happened with the new system they would have been EF5's. I guess my point is with the new system one would expect to see a lot more EF5's and they shouldnt be as rare as the older F5.

[natecast]

I understand that however in order for a tornado to get a F4 rating the damage had to be consistant with winds over 207 mph. Assuming that the damage surveys conducted in the past where accurate and all past F4's had winds over 200 mph wouldnt it figure that had they all happened with the new system they would have been EF5's. I guess my point is with the new system one would expect to see a lot more EF5's and they shouldnt be as rare as the older F5.

The winds estimated in older tornadoes using the F-scale where just that: estimates. Further reserach leading up to the EF-scale indicated winds did not have to be as strong as previously thought to generate the same type of damage. Sureyors first survey the damage, then estimate the wind speed from there, not vice-versa.

[jpeters3]

I understand that however in order for a tornado to get a F4 rating the damage had to be consistant with winds over 207 mph. Assuming that the damage surveys conducted in the past where accurate and all past F4's had winds over 200 mph wouldnt it figure that had they all happened with the new system they would have been EF5's. I guess my point is with the new system one would expect to see a lot more EF5's and they shouldnt be as rare as the older F5.

I could see how it would be confusing - confused the heck out of me when they introduced it. The point we are making is that prior wind speed estimates were too high - current ones for the EF scale are thought to be more accurate. In other words, a tornado rated to be F4 with estimated winds of 220 mph probably had winds closer to 170 mph.

[CUmet]

This may be of interest:

The weather service undertook a full day of storm surveys on Wednesday, mostly on the El Reno storm track. One of the participants came over to the HWT and gave us a briefing in the early afternoon. The damage pictures he showed were just phenomenal...I've never seen anything like it. Not even in the 3 May 1999 event. A large oil derrick, several stories tall and weighing millions of pounds, was knocked over and rolled several times; the workers sheltered in a small bunker that was strapped down with guy wires. One of the wires snapped, but the bunker survived. There were numerous examples of trees being debarked, grass being stripped from the soil, asphalt being stripped from roads, and well-constructed houses being swept completely clean off the foundation. He showed some pictures of mangled vehicles twisted together, some of which had been thrown large distances. An 18-wheeler was thrown 100 yards. A Ford Escalade (huge SUV) was thrown 900 yards. A compact car was found leaning against a tree with a 2x4 plank puncturing the floor of the car (it had come in through the window). If this damage isn't EF-5, I don't know what is. On Thursday night we went out for drinks with some people from OU, including a guy who had participated in the survey...he showed us a picture he had taken of a decapitated rabbit head lodged among debris in a debarked tree! Disturbing.

http://grubshanks.xa...tem/?ref=recent

[gymengineer]

I understand that however in order for a tornado to get a F4 rating the damage had to be consistant with winds over 207 mph. Assuming that the damage surveys conducted in the past where accurate and all past F4's had winds over 200 mph wouldnt it figure that had they all happened with the new system they would have been EF5's. I guess my point is with the new system one would expect to see a lot more EF5's and they shouldnt be as rare as the older F5.

I know two other posters tried to clear it up for you again above this post, but I just wanted to point out exactly where your confusion lies-- the bolded part. The surveyors surveyed the damage. They didn't measure the wind speeds. So where your assumption is wrong is "all past F4's had winds over 200 mph." They didn't... their wind speeds were overestimated because the Fujita scale had the "wrong" wind speeds matched up to each category. Maybe you're thinking of the Fujita scale like the Saffir Simpson scale, where the categories are determined by wind speeds. As others have explained, in the EF/Fujita scales, the damage is the determining factor for the rating.

[Calderon]

This may be of interest:

http://grubshanks.xa...tem/?ref=recent

pretty safe bet this beast is an EF-5

[AtticaFanatica]

Goldsby and Chickasha both high-end EF-4's, El Reno still being looked at.

[natecast]

Goldsby and Chickasha both high-end EF-4's, El Reno still being looked at.

Nothing's a given, but I'm pretty sure the El Reno-Piedmont tornado is going to be upgraded to EF-5. Could they possibly just be working out the wind speed estimates? Two other high-end EF-4's during the same outbreak is pretty darned impressive.

[AtticaFanatica]

Nothing's a given, but I'm pretty sure the El Reno-Piedmont tornado is going to be upgraded to EF-5. Could they possibly just be working out the wind speed estimates? Two other high-end EF-4's during the same outbreak is pretty darned impressive.

I know there has been spirited debate about the rating of all these tornadoes for quite a while now. There is additional information about the Piedmont tornado, maybe that is prolonging a final decision.

[thewxmann]

I dunno, if they're taking this long to decide on a rating, it's probably not gonna be an EF5. Perhaps many things favor an EF5 rating but the construction of the homes would preclude one (i.e. the usual 'rural homes are not as well constructed'). But borderline cases would get the lower rating.

[Amped]

I dunno, if they're taking this long to decide on a rating, it's probably not gonna be an EF5. Perhaps many things favor an EF5 rating but the construction of the homes would preclude one (i.e. the usual 'rural homes are not as well constructed'). But borderline cases would get the lower rating.

They gave Tuscolusa a EF4 190MPH for that reason, so they might as well be consistent and do it here too.

[natecast]

They gave Tuscolusa a EF4 190MPH for that reason, so they might as well be consistent and do it here too.

One would think it would be difficult to compare tornadoes that occur in an urban setting as opposed to a rural setting. It seems like it would be more difficult for a tornado to produce EF-5 damage when homes are clustered together in a neighborhood and debris is piling up and falling every which direction. Which makes the Joplin tornado even more amazing.

[thewxmann]

Check out this montage on Facebook. This was a home in Piedmont that appears to have been swept clean, and the home was bolted to the foundation. The pictures are also a great advertisement for safe rooms.

http://www.facebook....4178.1379126705

One would think it would be difficult to compare tornadoes that occur in an urban setting as opposed to a rural setting. It seems like it would be more difficult for a tornado to produce EF-5 damage when homes are clustered together in a neighborhood and debris is piling up and falling every which direction. Which makes the Joplin tornado even more amazing.

FYI, I am unable to view the montage.

It's actually much easier to produce an EF5 rating in an urban environment. One, debris in a tornado can compromise the structural integrity of buildings, making the winds that much more effective at doing damage; two, there are just that many more damage indicators in an urban setting. For instance, the Home Depot damage made the EF5 rating for the Joplin tornado that much easier to assign. You're not going to see that in rural OK. It's very hard to assign EF5 damage to homes because of different construction standards, etc. And usually, if there's doubt, the EF5 isn't given (just read the Tuscaloosa PNS, almost every paragraph provides some justification as to why EF5 wasn't assigned despite "homes swept clean").

[natecast]

FYI, I am unable to view the montage.

It's actually much easier to produce an EF5 rating in an urban environment. One, debris in a tornado can compromise the structural integrity of buildings, making the winds that much more effective at doing damage; two, there are just that many more damage indicators in an urban setting. For instance, the Home Depot damage made the EF5 rating for the Joplin tornado that much easier to assign. You're not going to see that in rural OK. It's very hard to assign EF5 damage to homes because of different construction standards, etc. And usually, if there's doubt, the EF5 isn't given (just read the Tuscaloosa PNS, almost every paragraph provides some justification as to why EF5 wasn't assigned despite "homes swept clean").

Sorry about that link, I forgot the pictures are set on a private setting and you've got to be friends with the poster. Also, my computer won't let me upload the pictures. Oh well.

You make good points about the urban versus rural setting for a tornado.

[AtticaFanatica]

El Reno rating will be released this afternoon with explanation. Hearing there is considerable disagreement, but it's looking like EF-4 despite some conflicting information.

[blackjack123]

El Reno rating will be released this afternoon with explanation. Hearing there is considerable disagreement, but it's looking like EF-4 despite some conflicting information.

There is so much debate between a high-end EF4 and an EF5 rating that it is almost sickening. There tends to be more scrutiny placed on an EF5 rating versus an EF4. I am not meaning any of this to be negative because there is a lot of debate. I mean you could call the Bridge Creek/Moore/OKC tornado from 1999 a high-end F4 or the Joplin tornado a high-end EF4. The only thing with these two tornadoes that it was only obvious to surveyors that there were structures built well enough to validate an F5/EF5 rating. Like said it is hard for tornadoes that hit only a few structures including a couple well-built homes swept off their foundations in rural areas to get an F5/EF5 rating. They could have very well been deserving of it although. A few of them I can think of would be 11-24-01(Mississippi), 6-23-02, 5-4-03(Girard/Franklin), 6-24-03(Manchester),5-12-04(Harper), 5-22-10(Bowdle)6-17-10(Holmes County, South Dakota), and 6-25-10( near Sibley, Iowa). The high-end F4/EF4 rating for all these tornadoes does seem like a reasonable estimate but I would not say F5/EF5 is impossible.

[AtticaFanatica]

EF5

[thewxmann]

EF5

Change of heart?