MNTornadoGuy

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Damage from the 1991 Itu F4. This is one of the few official F4s in Brazil.
vento-TornadoItu1A.jpg

vento-TornadoItu3A.jpg

vento-TornadoItu4A.jpg

 
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It depends on the swirl ratio, which is basically the relationship between the velocity of the air flowing into the tornado's core and the strength of the updraft. That, in turn, can vary depending on a huge range of factors, many of which aren't necessarily directly related to the actual intensity of the tornado. Even things like debris loading and surface roughness (rugged/forested vs. open field vs. populated area, etc.) have a major impact.

Which I guess is a long-winded way of saying that there aren't really any hard-and-fast rules - pretty much any kind of tornado can theoretically have any kind of internal structure. Just as an example, there doesn't seem to have been any evidence of multiple vortices through most of Bridge Creek-Moore's path.

There are a bunch of really fascinating studies on this and how it influences tornado intensity and whatnot. I'll try to find some of them again later.
Interesting, I always thought wedge tornadoes had multivortex structures, I learned something new here.
Here's a strange question; what do you think the maximum wind speeds were in the main funnel of Bridge Creek-Moore (not the core, the visible wedge) or in any violent wedge tornado? I know the cores and subvortices pack the 250+ mph winds, I'm just wondering if there's a limit to the visible condensation funnel's wind speeds. Not sure how else to phrase that.
 

MNTornadoGuy

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One interesting Texas tornado is the 1968 Edmonson TX tornado. This massive (>2 miles wide and the rotating mass of clouds was 3 miles wide) tornado moved 5 miles and produced intense damage. Topsoil was carried off along a 1/4 to 1/2 mile wide swath with fields being "so badly blown and washed they had no distinguishable beds left." Multiple farmhouses were destroyed with one farm losing all machinery and buildings. Unfortunately, not much information is available about this tornado.
 

locomusic01

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Interesting, I always thought wedge tornadoes had multivortex structures, I learned something new here.
Here's a strange question; what do you think the maximum wind speeds were in the main funnel of Bridge Creek-Moore (not the core, the visible wedge) or in any violent wedge tornado? I know the cores and subvortices pack the 250+ mph winds, I'm just wondering if there's a limit to the visible condensation funnel's wind speeds. Not sure how else to phrase that.
Broadly speaking, I would guess that the most violent tornadoes are probably more likely to be multivortex just because of the way swirl ratio works. Very much generalizing here, but if you think about the airflow in a tornado, air is drawn into/around the central low-pressure area and then has to "turn the corner" and be lifted upward. The region where that happens, appropriately enough, is called the corner flow region. That's basically what we think of as "the core," where the most extreme winds occur.

Anyway, the more momentum that air coming into the corner flow region has, the harder it is to lift it upward and the higher the swirl ratio. At a certain point, the momentum is such that the flow breaks down and forms into multiple smaller vortices. Since momentum = mass * velocity, you can see how a tornado with higher horizontal (more specifically tangential) velocities might be more likely to break down into multiple vortices.

Again, I'm simplifying and glossing over a ton of important stuff (updraft strength, debris loading, surface roughness, etc), but that's the general idea as I understand it.

As to your question, I'm not quite sure how to answer it. The condensation funnel itself is just a function of the local pressure deficit and humidity of the air. The wind field in a tornado is really complex and can change pretty rapidly, which you can sort of see in the radically different damage gradients/patterns. And then you can sometimes get particularly intense inflow jets and weird things like the "inflow vortices" that Greg Forbes described w/several of the 5/31/85 tornadoes, etc. They occur well outside of the core (and often outside of the funnel altogether) but can still produce pretty violent winds.
 

Marshal79344

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Broadly speaking, I would guess that the most violent tornadoes are probably more likely to be multivortex just because of the way swirl ratio works. Very much generalizing here, but if you think about the airflow in a tornado, air is drawn into/around the central low-pressure area and then has to "turn the corner" and be lifted upward. The region where that happens, appropriately enough, is called the corner flow region. That's basically what we think of as "the core," where the most extreme winds occur.

Anyway, the more momentum that air coming into the corner flow region has, the harder it is to lift it upward and the higher the swirl ratio. At a certain point, the momentum is such that the flow breaks down and forms into multiple smaller vortices. Since momentum = mass * velocity, you can see how a tornado with higher horizontal (more specifically tangential) velocities might be more likely to break down into multiple vortices.

Again, I'm simplifying and glossing over a ton of important stuff (updraft strength, debris loading, surface roughness, etc), but that's the general idea as I understand it.

As to your question, I'm not quite sure how to answer it. The condensation funnel itself is just a function of the local pressure deficit and humidity of the air. The wind field in a tornado is really complex and can change pretty rapidly, which you can sort of see in the radically different damage gradients/patterns. And then you can sometimes get particularly intense inflow jets and weird things like the "inflow vortices" that Greg Forbes described w/several of the 5/31/85 tornadoes, etc. They occur well outside of the core (and often outside of the funnel altogether) but can still produce pretty violent winds.
I feel that it should be generally accepted that all tornadoes have a multiple-vortex structure. I mean, multiple vortices have been seen in dust devils.
 

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So, since my article obviously won't be ready for today's anniversary, I wanted to at least share something. This is simply the most remarkable series of tornado photos I've ever seen, and I'm not sure it's even close. It's not clear exactly who took them, but they were taken from near the intersection of Broadway & Spearman avenues in Wheatland, looking to the south and southeast. This would've been almost exactly half a mile from the core of the tornado (this is the full width of the path, remember - the core is much narrower):

torphotos.jpg


Anyway, the first photo here is taken when the tornado is roughly near the river.

wheatland-tornado-1-mike-sisic.jpg


By the second photo, you can already see it striking Yourga Trucking. I believe the huge piece of debris here is the roof, most of which was ripped off in one piece, crumpled up and tossed over a quarter-mile into someone's yard.

wheatland-tornado-2-mike-sisic.jpg


I think it's probably tearing up Wheatland Tube here, which is right next door.

wheatland-tornado-3-mike-sisic.jpg


In the next few photos, it's likely demolishing Sawhill Tubular and a number of homes scattered around it. The third photo especially gives you a better view of just how small the core is relative to the entire funnel/circulation.

wheatland-tornado-4-mike-sisic.jpg


wheatland-tornado-5-mike-sisic.jpg


wheatland-tornado-6-mike-sisic.jpg


Though the damage throughout this area is exceptionally intense, arguably the most violent damage along the entire path occurs as the tornado crosses the railroad tracks, growing a bit larger as it utterly obliterates a number of homes, businesses and industrial buildings.

wheatland-tornado-7-mike-sisic.jpg


wheatland-tornado-8-mike-sisic.jpg


wheatland-tornado-9-mike-sisic.jpg


wheatland-tornado-10-mike-sisic.jpg


wheatland-tornado-11-mike-sisic.jpg


Basically the entire funnel swarms with debris as it finally speeds away across an unpopulated area.

wheatland-tornado-12-mike-sisic.jpg


wheatland-tornado-13-mike-sisic.jpg


wheatland-tornado-14-mike-sisic.jpg
 

locomusic01

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On a somewhat related note, it turns out that I don't actually know how many people were killed during this outbreak. It seems no one does. The official toll is 90, but in the process of mapping the fatalities I've found out about at least four people so far who later died (most within a few months, but in one case a couple of years later) and whose deaths seem to be directly attributable to injuries suffered in one of the tornadoes. I wasn't even specifically looking for them at the time, so it makes me wonder if there might be others as well.

Edit: Actually one of them died within hours but, for some reason, doesn't appear to have been counted anywhere.
 

MNTornadoGuy

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So, since my article obviously won't be ready for today's anniversary, I wanted to at least share something. This is simply the most remarkable series of tornado photos I've ever seen, and I'm not sure it's even close. It's not clear exactly who took them, but they were taken from near the intersection of Broadway & Spearman avenues in Wheatland, looking to the south and southeast. This would've been almost exactly half a mile from the core of the tornado (this is the full width of the path, remember - the core is much narrower):

torphotos.jpg


Anyway, the first photo here is taken when the tornado is roughly near the river.

wheatland-tornado-1-mike-sisic.jpg


By the second photo, you can already see it striking Yourga Trucking. I believe the huge piece of debris here is the roof, most of which was ripped off in one piece, crumpled up and tossed over a quarter-mile into someone's yard.

wheatland-tornado-2-mike-sisic.jpg


I think it's probably tearing up Wheatland Tube here, which is right next door.

wheatland-tornado-3-mike-sisic.jpg


In the next few photos, it's likely demolishing Sawhill Tubular and a number of homes scattered around it. The third photo especially gives you a better view of just how small the core is relative to the entire funnel/circulation.

wheatland-tornado-4-mike-sisic.jpg


wheatland-tornado-5-mike-sisic.jpg


wheatland-tornado-6-mike-sisic.jpg


Though the damage throughout this area is exceptionally intense, arguably the most violent damage along the entire path occurs as the tornado crosses the railroad tracks, growing a bit larger as it utterly obliterates a number of homes, businesses and industrial buildings.

wheatland-tornado-7-mike-sisic.jpg


wheatland-tornado-8-mike-sisic.jpg


wheatland-tornado-9-mike-sisic.jpg


wheatland-tornado-10-mike-sisic.jpg


wheatland-tornado-11-mike-sisic.jpg


Basically the entire funnel swarms with debris as it finally speeds away across an unpopulated area.

wheatland-tornado-12-mike-sisic.jpg


wheatland-tornado-13-mike-sisic.jpg


wheatland-tornado-14-mike-sisic.jpg
Did any of the Canadian tornadoes from the outbreak produce very impressive damage?
 

locomusic01

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Did any of the Canadian tornadoes from the outbreak produce very impressive damage?
Barrie, of course, but I was surprised to find that Grand Valley produced some isolated instances of pretty high-end damage as well. Despite its very long track, most of what you normally see from that tornado comes from Grand Valley itself, and that wasn't where it was most intense.

grandvalley.jpg


Obviously neither tornado was even in the same neighborhood as Niles-Wheatland, but they were legit violent. The Corbetton F3 (often called the Mansfield tornado even though it didn't pass particularly close to there) seems to have been fairly intense as well, although I haven't come across many photos yet.
 

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Damage and photos from the Kokomo-Greentown tornado.
This tornado threw a number of vehicles significant distances, especially between Greentown and Swayzee. This one was thrown a couple hundred yards.

26155-10150172589595171-2061486-n.jpg


The first one here was apparently thrown around half a mile (I'll never not be amused by how incongruous this photo is).

greentown-cars.jpg


And a car parked in one of the driveways in the famous Greentown aerial shot was also thrown > 1/2 mile.

greentown-aerial.jpg


A few vehicles were apparently "crushed" around this area as well, although I don't have any specifics.

howard-county-scoured-ground.jpg


Sort of gets overlooked, I think, but it was a very violent tornado. The damage around the outskirts of Marion was nearly as intense as Greentown in some places.
 

MNTornadoGuy

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This tornado threw a number of vehicles significant distances, especially between Greentown and Swayzee. This one was thrown a couple hundred yards.

26155-10150172589595171-2061486-n.jpg


The first one here was apparently thrown around half a mile (I'll never not be amused by how incongruous this photo is).

greentown-cars.jpg


And a car parked in one of the driveways in the famous Greentown aerial shot was also thrown > 1/2 mile.

greentown-aerial.jpg


A few vehicles were apparently "crushed" around this area as well, although I don't have any specifics.

howard-county-scoured-ground.jpg


Sort of gets overlooked, I think, but it was a very violent tornado. The damage around the outskirts of Marion was nearly as intense as Greentown in some places.
Greentown was probably an F5
 

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The fact that Palm Sunday "officially" has zero F5s is genuinely baffling, not only because there are multiple strong candidates (Greentown definitely being one of them) but also because some of the official F5s from that era are either egregiously overrated or rated based on very little evidence.
 

TH2002

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While I know some basic details about the 8/10/1924 Thurman, CO tornado in that a farmhouse was leveled or swept away killing 10 of the 18 people inside and that the tornado was an F4 to marginal F5 I would like more details.

Anyone have damage pics, and what was the tornado rated by Fujita and Grazulis?
 

locomusic01

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While I know some basic details about the 8/10/1924 Thurman, CO tornado in that a farmhouse was leveled or swept away killing 10 of the 18 people inside and that the tornado was an F4 to marginal F5 I would like more details.

Anyone have damage pics, and what was the tornado rated by Fujita and Grazulis?
I haven't done any research on it, but here's Grazulis' entry:

CO AUG 10, 1924 1345 10k 8inj 200y 20m F4
WASHINGTON / KIT CARSON - Moved ESE from 4m ENE of Thurman, destroying one farm. Four families had gathered for Mennonite services at the close of harvesting. After the meal, five funnel clouds were spotted in the distance, and two appeared to touch down. The men left on what might have been a rescue mission. No damage was found. They returned in time to see their own home being swept away by another tornado, killing nine children, one woman, and seriously injuring the other occupants.
 

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I haven't done any research on it, but here's Grazulis' entry:

CO AUG 10, 1924 1345 10k 8inj 200y 20m F4
WASHINGTON / KIT CARSON - Moved ESE from 4m ENE of Thurman, destroying one farm. Four families had gathered for Mennonite services at the close of harvesting. After the meal, five funnel clouds were spotted in the distance, and two appeared to touch down. The men left on what might have been a rescue mission. No damage was found. They returned in time to see their own home being swept away by another tornado, killing nine children, one woman, and seriously injuring the other occupants.
Thank you!

Thurman 1924 is one of only a few tornadoes I can think of off the top of my head (others being Natchez 1840 and Golden City, MO 2019) to kill more then they injured.
 

MNTornadoGuy

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While I know some basic details about the 8/10/1924 Thurman, CO tornado in that a farmhouse was leveled or swept away killing 10 of the 18 people inside and that the tornado was an F4 to marginal F5 I would like more details.

Anyone have damage pics, and what was the tornado rated by Fujita and Grazulis?
damage.jpg

foundatn.jpg
 

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