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Significant Tornado Events (1 Viewer)


Messages
74
Location
Lenexa, KS
Laverne was almost without question violent, just didn't hit a DI capable of registering it. Same with several of these plains tornadoes.
I feel like a lot of NWS offices are too stringent and some are too lenient. Has there been any studies on extreme ground scouring, throwing vehicles long distances and mangling them beyond recognition, or other non DI indicators that are usually associated with violent tornadoes?
 

Equus

Member
Messages
1,238
Location
Saragossa, AL
I hope they address it in the update to the EF scale coming up. There might be too many variables involved in those things to actually make them a DI but I would like to see official guidelines since WFOs handle those things very differently. I know back in the 1970s at the beginning of the Fujita scale, tossing a car a certain distance was considered F5 but this was changed; F3/EF3s can do that, but crumpling them into small balls and wrapping them around trees or tearing them completely apart and scattering them in little pieces seems to be the hallmark of violent tornadoes.

This all may be better suited for the other thread (EF debates) though.
 

locomusic01

Member
Messages
84
Location
Pennsylvania
The last I heard was that some of the SPC/NWS folks were looking into reevaluating the EF-scale, particularly when it comes to expanding non-structural DIs like vegetation damage, vehicles, farm equipment, transmission towers, etc. This was probably a year or two ago, so I don't know how it's progressed since then. It's something they're definitely aware of and working to figure out, though.

Ground scouring is the really tricky one. There are just so many variables - soil type, grass type, moisture, etc. That's part of the reason you'll sometimes see relatively weaker tornadoes produce very clear scouring while some high-end ones don't. Deep scouring like in Jarrell, Philadelphia, etc. is certainly more likely to be indicative of a very violent tornado, but even then, it may not be enough evidence in and of itself. And of course asphalt scouring presents some of the same problems, with variations in the integrity of the asphalt and the state of the road bed and so on.

I know there have also been a few papers that have looked at the behavior of vehicles in tornadoes. Somewhat surprisingly, it appears a fair percentage of vehicles aren't actually lofted even in violent tornadoes. And conversely, even sub-violent tornadoes occasionally do loft them. Still, my very amateur opinion is that extreme vehicle damage is among the most reliable violent tornado indicators outside of high-end structural damage.
 

warneagle

Member
Messages
1,530
Location
Silver Spring, MD
Special Affiliations
SKYWARN® Volunteer
The last I heard was that some of the SPC/NWS folks were looking into reevaluating the EF-scale, particularly when it comes to expanding non-structural DIs like vegetation damage, vehicles, farm equipment, transmission towers, etc. This was probably a year or two ago, so I don't know how it's progressed since then. It's something they're definitely aware of and working to figure out, though.

Ground scouring is the really tricky one. There are just so many variables - soil type, grass type, moisture, etc. That's part of the reason you'll sometimes see relatively weaker tornadoes produce very clear scouring while some high-end ones don't. Deep scouring like in Jarrell, Philadelphia, etc. is certainly more likely to be indicative of a very violent tornado, but even then, it may not be enough evidence in and of itself. And of course asphalt scouring presents some of the same problems, with variations in the integrity of the asphalt and the state of the road bed and so on.

I know there have also been a few papers that have looked at the behavior of vehicles in tornadoes. Somewhat surprisingly, it appears a fair percentage of vehicles aren't actually lofted even in violent tornadoes. And conversely, even sub-violent tornadoes occasionally do loft them. Still, my very amateur opinion is that extreme vehicle damage is among the most reliable violent tornado indicators outside of high-end structural damage.
I feel like there's a good dissertation in geology or something on ground scouring as a DI, but I think there might be too much variability in terms of soil types, moisture, etc. to have it be a standardized DI, to say nothing of potential differences in terms of whether all violent tornadoes cause the same level of scouring at the same intensity, etc. I guess railroad tracks aren't a frequently encountered DI but it might be nice to have a standard for it just in case, since what happened in Chapman certainly indicated a violent tornado if not necessarily an EF5.
 

buckeye05

Member
Messages
210
Location
Riverside, Ohio
Ok so I just got back from surveying the EF4 damage swath from the Dayton tornado. I gotta say, NWS Wilmington was pretty liberal by rating that tornado EF4 based mostly on tree damage, but with that said, this was the most impressive tree damage I have ever seen in person. It appears that the most violent winds from this tornado funneled into the small valley where the Stillwater River is, behind some apartments on Spring Creek Drive. The wooded area along the river is completely shredded and decimated, with countless large and healthy hardwood trees completely stripped of bark and limbs. It looks consistent with tree damage that I have seen photographed after only the most violent of tornadoes. With that said, I did NOT find any clear cut EF4 structural damage. There are some very heavily damaged apartment buildings in this area that were rated low-end EF4 by our local WFO, but none are leveled. It appears to me that the EF4 winds funneled down along the river and did not impact any structures.

Overall I agree that EF4 winds occurred based on this vegetation damage, but I think somehow, these winds only impacted trees. So I agree with the rating, just surprised at how they applied such a rating without any clear EF4 structural damage.
 
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buckeye05

Member
Messages
210
Location
Riverside, Ohio
Also I want to mention, this recent outbreak was a humbling experience for me. I haven't been posting a lot because I've been processing what happened. This affected me way more than I thought it would emotionally. I actually left Dayton before the warning was even issued, because I had a gut feeling that something terrible was about to happen. Talking on the phone with my parents and watching the debris ball move right through their suburb, and hearing my sister in an absolute panic in the background is something I never want to experience again. Seeing what's left of businesses where I've shopped or eaten dinner at many times is also completely surreal.

My cousin had the closest call. Her townhouse sustained EF3 damage while she and her young son were inside. She had fallen asleep on the couch downstairs and woke up to the building shaking and her ears popping. She ran upstairs to pull her son out of bed, but couldn't get the door open due to the pressure. She heard his window shatter and then the door opened. She grabbed him and ran down the stairs with him while the roof lifted off and the exterior walls fell outward from the building. By the time they reached the bottom of the stairs, the tornado had already passed. They are very, very lucky to say the least.
 
Messages
74
Location
Lenexa, KS
Ok so I just got back from surveying the EF4 damage swath from the Dayton tornado. I gotta say, NWS Wilmington was pretty liberal by rating that tornado EF4 based mostly on tree damage, but with that said, this was the most impressive tree damage I have ever seen in person. It appears that the most violent winds from this tornado funneled into the small valley where the Stillwater River is, behind some apartments on Spring Creek Drive. The wooded area along the river is completely shredded and decimated, with countless large and healthy hardwood trees completely stripped of bark and limbs. It looks consistent with tree damage that I have seen photographed after only the most violent of tornadoes. With that said, I did NOT find any clear cut EF4 structural damage. There are some very heavily damaged apartment buildings in this area that were rated low-end EF4 by our local WFO, but none are leveled. It appears to me that the EF4 winds funneled down along the river and did not impact any structures.

Overall I agree that EF4 winds occurred based on this vegetation damage, but I think somehow, these winds only impacted trees. So I agree with the rating, just surprised at how they applied such a rating without any clear EF4 structural damage.
So was the area you looked at pretty desolate. Desolation of certain areas where there is extensive ground scouring and trees completely stripped of there bark seem to occur in the most violent of tornadoes. Even the Greensburg tornado left at least one or two small areas desolate. Though the EF5 rating was mainly because of 7 well-built homes that were swept away.
 
Messages
398
Location
Niagara Falls, Ontario
One of the most interesting tornadoes to me has always been the Teton/Yellowstone tornado on July 21, 1987. As far as I know it was the most remote and the highest-altitude violent tornado on record, and even though it didn't cause any damage to structures or property, the tree damage was unbelievable. According to the Wyoming Climate Atlas, nearly one million trees were snapped or uprooted, and literally thousands were completely debarked and had their branches removed. A number of these debarked trunks were plastered in mud and debris as well. Fujita apparently said that the tree damage was some of the worst he had ever seen, and compared it to the tree damage from the Guin and Tanner, AL tornadoes on 4/3/74 and the Smithfield, AL tornado on 4/4/77.


This is the only image of the damage path I was able to find. The most extreme tree damage seems to be in a narrow streak through the upper center of the photo, but the tornado itself was more than 1.5 miles wide.

Probably the biggest question mark out of this tornado is the fact that F3 to F4-level tree damage occurred at elevations of 9,000 feet and higher, with the highest peaks crossed by the tornado being at nearly 11,000 feet. The Wyoming Climate Atlas has stated that the winds needed to cause this kind of tree damage at higher altitudes is probably a fair bit higher than at lower altitudes where the air pressure is higher, and so the tornado's winds could be much stronger than official estimates. Honestly, the true damage potential of this tornado, if it had happened closer to sea level, will probably never be known.
 
Messages
74
Location
Lenexa, KS
One of the most interesting tornadoes to me has always been the Teton/Yellowstone tornado on July 21, 1987. As far as I know it was the most remote and the highest-altitude violent tornado on record, and even though it didn't cause any damage to structures or property, the tree damage was unbelievable. According to the Wyoming Climate Atlas, nearly one million trees were snapped or uprooted, and literally thousands were completely debarked and had their branches removed. A number of these debarked trunks were plastered in mud and debris as well. Fujita apparently said that the tree damage was some of the worst he had ever seen, and compared it to the tree damage from the Guin and Tanner, AL tornadoes on 4/3/74 and the Smithfield, AL tornado on 4/4/77.


This is the only image of the damage path I was able to find. The most extreme tree damage seems to be in a narrow streak through the upper center of the photo, but the tornado itself was more than 1.5 miles wide.

Probably the biggest question mark out of this tornado is the fact that F3 to F4-level tree damage occurred at elevations of 9,000 feet and higher, with the highest peaks crossed by the tornado being at nearly 11,000 feet. The Wyoming Climate Atlas has stated that the winds needed to cause this kind of tree damage at higher altitudes is probably a fair bit higher than at lower altitudes where the air pressure is higher, and so the tornado's winds could be much stronger than official estimates. Honestly, the true damage potential of this tornado, if it had happened closer to sea level, will probably never be known.
Wow, that is very impressive. Those trees look like toothpicks and splinters.
 

Equus

Member
Messages
1,238
Location
Saragossa, AL
There are a few more photos in the Monthly Weather Review article but nothing at ground level. Too bad the damage path burned the following year. Undoubtedly one of those freak occurrences like the 5/31/85 outbreak or the Russian outbreak... all of which ironically happened in the 80s. Actually, looking at things, the anomalous Edmonton F4 happened just ten days after the Yellowstone tornado; must have been a highly interesting large scale setup in the west that summer
 
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pohnpei

Member
Messages
2
Location
shanghai
What fascinates me is the part of the world that outbreak happened. We have comparable outbreaks in the US a few times a century, but imagine how exceptionally rare conditions favorable for an outbreak of that intensity must be in Russia. Wonder if synoptic and surface charts across Europe would be anywhere near complete enough over the last century to tell how often a setup like that happens.
As for the Russian tornado, I think this paper is very interesting:I https://www.sciencedirect.com/science/article/abs/pii/S0034425717304662?via=ihub
The specific research area of this paper is located in the Russian inland area between 52 and 67 degrees in the north latitude and 27 to 60 degrees in the East longitude. Forest coverage varies from 10% to 98% in the region. Only one tornado has been reported in this area in the past 15 years. This paper has found 110, some of which are very impressive. The largest tornado was 2 kilometers wide and the longest tornado was 80 kilometers long. In addition, the tornado outbreak on June 23, 2007 occurred between 61 and 64 degrees north latitude.
Similar terrain conditions have made the Northeast Plain of China another underestimated tornado active area. Despite insufficient information, I am quite sure that the outbreak here on July 31, 1987 was the strongest tornado outbreak in East Asian history.
1830
1829
 
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locomusic01

Member
Messages
84
Location
Pennsylvania
Also I want to mention, this recent outbreak was a humbling experience for me. I haven't been posting a lot because I've been processing what happened. This affected me way more than I thought it would emotionally. I actually left Dayton before the warning was even issued, because I had a gut feeling that something terrible was about to happen. Talking on the phone with my parents and watching the debris ball move right through their suburb, and hearing my sister in an absolute panic in the background is something I never want to experience again. Seeing what's left of businesses where I've shopped or eaten dinner at many times is also completely surreal.

My cousin had the closest call. Her townhouse sustained EF3 damage while she and her young son were inside. She had fallen asleep on the couch downstairs and woke up to the building shaking and her ears popping. She ran upstairs to pull her son out of bed, but couldn't get the door open due to the pressure. She heard his window shatter and then the door opened. She grabbed him and ran down the stairs with him while the roof lifted off and the exterior walls fell outward from the building. By the time they reached the bottom of the stairs, the tornado had already passed. They are very, very lucky to say the least.
That's terrifying - I'm glad everyone was okay!
 

locomusic01

Member
Messages
84
Location
Pennsylvania
One of the most interesting tornadoes to me has always been the Teton/Yellowstone tornado on July 21, 1987. As far as I know it was the most remote and the highest-altitude violent tornado on record, and even though it didn't cause any damage to structures or property, the tree damage was unbelievable. According to the Wyoming Climate Atlas, nearly one million trees were snapped or uprooted, and literally thousands were completely debarked and had their branches removed. A number of these debarked trunks were plastered in mud and debris as well. Fujita apparently said that the tree damage was some of the worst he had ever seen, and compared it to the tree damage from the Guin and Tanner, AL tornadoes on 4/3/74 and the Smithfield, AL tornado on 4/4/77.


This is the only image of the damage path I was able to find. The most extreme tree damage seems to be in a narrow streak through the upper center of the photo, but the tornado itself was more than 1.5 miles wide.

Probably the biggest question mark out of this tornado is the fact that F3 to F4-level tree damage occurred at elevations of 9,000 feet and higher, with the highest peaks crossed by the tornado being at nearly 11,000 feet. The Wyoming Climate Atlas has stated that the winds needed to cause this kind of tree damage at higher altitudes is probably a fair bit higher than at lower altitudes where the air pressure is higher, and so the tornado's winds could be much stronger than official estimates. Honestly, the true damage potential of this tornado, if it had happened closer to sea level, will probably never be known.
I hesitate to say this because I have tremendous respect for Dr. Fujita and obviously he knew far, far more than I ever will, but I can't help wondering a bit about the F4 rating. Clearly the Teton tornado was intense, but Engelmann spruce is a very soft, light wood. The trees have surprisingly shallow roots for their size and the bark is very thin and loosely attached. I'm not sure it'd take extreme velocities to produce wide treefalls and debarking/denuding.

On the other hand, studies have suggested that the relative location of the treefall convergence line is a potential indicator of intensity. In violent tornadoes, the convergence line tends to be well to the left (meaning north in most cases) of the center of the track. In weaker tornadoes, it's closer to the center or to the right. The convergence line in this case was to the left of center based on Fujita's mapping. Of course, complex terrain and wind effects mean there's a lot of variation, but that's the overall pattern. So, that's potentially suggestive of a high-end tornado.

Another interesting thing is the suggestion by Fujita and others that the cloud base may have been below the elevation of the damage:

It is quite possible that the mesocyclone cloud base was below the elevation of Enos Lake at 2382m MSL, and the entire damage occurred just above the cloud base. Consequently, no funnel cloud existed while destructive winds were on the ground. Witnesses to the storm, in a group of nine, on a camping trip near Enos Lake said they saw no funnel cloud and that the storm happened very quickly with a roar like a train in the distance.
Fujita also said this:

The only F4 damage in a forest comparable to t his one was photographed from a Cessna by the author in the Appalachians after the F4 Murphy Tornado in North Carolina on 3 April 1974.
I have a couple of photos of that damage, but only one is of sufficient quality to make out anything useful. Just an interesting point of comparison.

1831
 
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locomusic01

Member
Messages
84
Location
Pennsylvania
So, this is pretty wild. On June 18, 1975, a family of eight tornadoes struck roughly between the towns of Bartley and Arnold in Central Nebraska (called the Gothenburg tornado family in reference to the biggest town in the area). Many of the paths were separated by relatively short distances such that it was first reported as a single tornado with a 90-mile length. Five of the tornadoes were rated F3 and one, near Arnold, was rated F4. There were reports of multiple tornadoes on the ground at once, satellite tornadoes, horizontal vortices, etc. At least one of the tornadoes looked rather visually imposing (this was near Peterson, NE):

1833

Anyhow, that's not the really interesting bit. No, what makes this event most notable is that it did some distinctly Philadelphia, MS-esque things. To wit:

1836

1837

1838

Bit hard to make it out, but here's what you're looking at. The tornado near Moorefield, NE created a "hole" that measured about 10 ft by 6.5 ft and up to 18.5 inches deep. It also created a "crack" that appears to be about the same length as the hole but much narrower. The sides are sharp and steep in some places and more gradual in others. There are a few broken chunks of sod downstream from these features, but otherwise not much else. There's a mangled windmill barely visible in the background of the first picture, but it apparently wasn't associated with these features and there don't seem to be any other debris/missile-related causes.

Greg Forbes studied the event and postulated that some combination of lightning + suction vortex could've caused it, but he was operating under the assumption that tornadic winds alone couldn't do the job. Of course, we've seen since then that tornadoes can indeed do this sort of thing. He took an interesting approach of using soil shear-strength tests to estimate that velocities in the range of 246-291 mph would be required for wind alone. His objection was that the wind speed at the surface must necessarily be zero given the boundary layer physics involved. That stuff's above my pay grade, but my sense is that it's more a theoretical principle than a practical one - given the turbulence of wind flows in tornadoes, the updrafts and downdrafts, variations in surface roughness, debris loading, etc. it seems clear to me that it doesn't hold up in the real world.

Oh, the later F4 tornado near Arnold also did this:

1839

1840

The "O" in the first photo represents the approximate starting location of a pair of combines, one of which weighed 18,500 lbs and the other slightly less. The heavier combine was tossed a tenth of a mile to the location marked "L" and the lighter one, pictured in the second photo, came to rest 0.16 miles away in the spot marked "B." Grain bins and other assorted bits of large debris were lofted pretty substantial distances as well. Trees in the direct path of this tornado at its most intense were also reportedly stripped bare, some of them snapped off just a few feet above ground level.

All in all, another rather impressive (and probably underrated) event that's gone mostly unnoticed because of the remote Nebraska location.
 

Attachments

andyhb

Member
Messages
67
Location
Norman, OK
As for the Russian tornado, I think this paper is very interesting:I https://www.sciencedirect.com/science/article/abs/pii/S0034425717304662?via=ihub
The specific research area of this paper is located in the Russian inland area between 52 and 67 degrees in the north latitude and 27 to 60 degrees in the East longitude. Forest coverage varies from 10% to 98% in the region. Only one tornado has been reported in this area in the past 15 years. This paper has found 110, some of which are very impressive. The largest tornado was 2 kilometers wide and the longest tornado was 80 kilometers long. In addition, the tornado outbreak on June 23, 2007 occurred between 61 and 64 degrees north latitude.
Similar terrain conditions have made the Northeast Plain of China another underestimated tornado active area. Despite insufficient information, I am quite sure that the outbreak here on July 31, 1987 was the strongest tornado outbreak in East Asian history.
What's more interesting to me is that both of these days were also the same periods as violent Canadian tornadoes (Elie/Pipestone in 2007 and Edmonton in 1987). The Russian outbreak in 1984 came during the same period as the outbreak that produced the Barneveld, WI F5 and several other significant tornadoes. Small sample size, but perhaps there is some planetary scale linkage here in the upper air patterns.
 
Messages
74
Location
Lenexa, KS
So, this is pretty wild. On June 18, 1975, a family of eight tornadoes struck roughly between the towns of Bartley and Arnold in Central Nebraska (called the Gothenburg tornado family in reference to the biggest town in the area). Many of the paths were separated by relatively short distances such that it was first reported as a single tornado with a 90-mile length. Five of the tornadoes were rated F3 and one, near Arnold, was rated F4. There were reports of multiple tornadoes on the ground at once, satellite tornadoes, horizontal vortices, etc. At least one of the tornadoes looked rather visually imposing (this was near Peterson, NE):

View attachment 1833

Anyhow, that's not the really interesting bit. No, what makes this event most notable is that it did some distinctly Philadelphia, MS-esque things. To wit:

View attachment 1836

View attachment 1837

View attachment 1838

Bit hard to make it out, but here's what you're looking at. The tornado near Moorefield, NE created a "hole" that measured about 10 ft by 6.5 ft and up to 18.5 inches deep. It also created a "crack" that appears to be about the same length as the hole but much narrower. The sides are sharp and steep in some places and more gradual in others. There are a few broken chunks of sod downstream from these features, but otherwise not much else. There's a mangled windmill barely visible in the background of the first picture, but it apparently wasn't associated with these features and there don't seem to be any other debris/missile-related causes.

Greg Forbes studied the event and postulated that some combination of lightning + suction vortex could've caused it, but he was operating under the assumption that tornadic winds alone couldn't do the job. Of course, we've seen since then that tornadoes can indeed do this sort of thing. He took an interesting approach of using soil shear-strength tests to estimate that velocities in the range of 246-291 mph would be required for wind alone. His objection was that the wind speed at the surface must necessarily be zero given the boundary layer physics involved. That stuff's above my pay grade, but my sense is that it's more a theoretical principle than a practical one - given the turbulence of wind flows in tornadoes, the updrafts and downdrafts, variations in surface roughness, debris loading, etc. it seems clear to me that it doesn't hold up in the real world.

Oh, the later F4 tornado near Arnold also did this:

View attachment 1839

View attachment 1840

The "O" in the first photo represents the approximate starting location of a pair of combines, one of which weighed 18,500 lbs and the other slightly less. The heavier combine was tossed a tenth of a mile to the location marked "L" and the lighter one, pictured in the second photo, came to rest 0.16 miles away in the spot marked "B." Grain bins and other assorted bits of large debris were lofted pretty substantial distances as well. Trees in the direct path of this tornado at its most intense were also reportedly stripped bare, some of them snapped off just a few feet above ground level.

All in all, another rather impressive (and probably underrated) event that's gone mostly unnoticed because of the remote Nebraska location.
Yes, I have heard Dr. Greg mention this event before and compared It with the ground scouring done in Philadelphia Mississippi. Those damage photos show incredible damage.
 

andyhb

Member
Messages
67
Location
Norman, OK

45th anniversary of this day, the second historic outbreak of 1974. You won’t find much to compete with this event in June over the S Plains.
 

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