Greensburg/Trousdale tornado 4 miles wide?

[Lanny Dean]

Your question could be understood a couple of ways, Shane, so I'll address them both.

* If you mean the size of the wedge being expanded beyond 2.5 miles--good question. The paper indicates it was 4.1 km, which figures out to 2.5 miles, not 2.7, as mentioned by one poster. As for the 2.8 figure in my own previous post, that was my error, and I'm glad you caught it. I went back to the paper and double-checked, and will make the correction in my earlier post if I can still edit. The tornado was already of a sensational size and doesn't need to be oversensationalized.

* If you're referring to the 4-mile-wide figure, that's an area of speculation that really is the core of this thread. The paper documents a tornado cyclone 7 km across. That converts to 4.3 miles. And the wind speeds evidently were of tornadic intensity, and may have extended to ground level. Here are some relevant quotes from the paper:

Are we resolving a larger and stronger tornado cyclone than previously reported? Are we actually resolving a very strong and large tornado by KDDC? (This may well be the case)...

To reinforce the statement made earlier in section 3.1, this vortex appears to be on the spatial scale of the mesocyclone, but with mean velocity on the scale of the tornado...

...We estimate actual TC tangential velocity of 74 m s-1 or 144 kts.
This becomes even more amazing when at 0433 the radar resolved core circulation TC at 0.5o has grown to 7 km (3.9 nm) across with a mean tangential velocity of 52 m s-1 or 101 kts!

These statements obviously leave things up for speculation. Did a four-mile-wide tornado actually occur? Looks like the best answer is, very possibly. But at this point, it can't be firmly established. From what I gather, Lemon and Umscheid presently are referring to the circulation as just an extraordinarily intense tornado cyclone.

Bob,
First of all, I can only hope that such noted and respected scientists and meteorologists as Lemon and even Mike would not just leave us with speculation of such a possible dramatic find.
As I said in an earlier post and as we all know, by definition, if it made ground contact it would be considered a tornado. As you have noted, the circulation definitely was of tornadic proportion/strength
with observed data of over 100kts. Maybe Mike U. can shed some more light on the matter if he is available?


"Are we resolving a larger and stronger tornado cyclone than previously reported? Are we actually resolving a very strong and large tornado by KDDC? (This may well be the case)"...

 

[Shane Adams]

I was mainly referring to the tornado after Greensburg, which was recorded at 2.2 miles wide in Storm Data. That being a significant size, plus with all the hoopla the Hallam tornado got as being the biggest ever at 2.5, it just seemed kinda odd to me that it was "upgraded" to 2.8 miles wide, with no mention of it being the largest ever or even being changed from the original estimate of 2.2 miles wide.

FWIW, here's a shot of part of this tornado. The left 1/3 of the image shows the right part of the tornado, I have no idea how much more was off-camera. This is around 10:30pm CDT, east of Haviland, looking northwest:

 

[Bob Hartig]

All reports and calculations and speculations aside--man, I wish I'd been there to see that.

Then again, maybe not.

 

[Mike Umscheid]

Thanks everyone for all the compliments and I'm glad you found our paper interesting! It was a pretty stressful september and october getting the paper written for the conference. It's a lot longer than a conferece paper usually is... we're probably not far off from getting something submitted for a formal publication. Table 1 is in error, as Shane and others have found. StormData is correct... all of our numbers for the stats came from the StormData entries except for mean width which we computed from the shape file our (NWS DDC) WCM produced. Les incorrectly used "nm" instead of "statute miles" when he wrote his sections, and when I did the final editing, I just simply converted the incorrect 1.7 nm (should have been 1.7 statute miles) to km. So, unfortunately, path length and maximum widths are too large because of a units conversion error.

When it comes to the journal article we hope to get out there sometime, we want to include some of Howie Bluestein's X-band dual pol data as part of the discussion regarding the Greensburg tornado from 0200 to 0237 UTC.

Mike U

 

[Sarah Austin]

This is very fascinating! Nice job on the paper!! We were approximately 4 miles south of where the Greensburg tornado crossed 183. In a few of our video stills, it appears that there were actually 2 tornadoes instead of just one because it was so wide. It's nice to see all the tornado paths on one chart. I had heard the Trousdale tornado was actually wider, but did not realize how wide until now.

 

[Lanny Dean]

Thanks everyone for all the compliments and I'm glad you found our paper interesting! It was a pretty stressful september and october getting the paper written for the conference. It's a lot longer than a conferece paper usually is... we're probably not far off from getting something submitted for a formal publication. Table 1 is in error, as Shane and others have found. StormData is correct... all of our numbers for the stats came from the StormData entries except for mean width which we computed from the shape file our (NWS DDC) WCM produced. Les incorrectly used "nm" instead of "statute miles" when he wrote his sections, and when I did the final editing, I just simply converted the incorrect 1.7 nm (should have been 1.7 statute miles) to km. So, unfortunately, path length and maximum widths are too large because of a units conversion error.

When it comes to the journal article we hope to get out there sometime, we want to include some of Howie Bluestein's X-band dual pol data as part of the discussion regarding the Greensburg tornado from 0200 to 0237 UTC.

Mike U

Mike, thanks for clearing that up.
I was wondering when Howies info and data were going to come into play.
I passed him somewhere south of Coldwater....did not know he actually had a flat or I would have stopped to help.
Anyways, obviously Greensburg has much meaning to me so when I found the paper I thought it would be a good idea to share it with everyone here on ST.
Very good paper, kuddos.... and thanks for corresponding as well as clearing up the info here, that said, straight to the main point.....are we looking at a 4 mile wide tornado?

 

[Darin Brunin]

It still amazes me that that however big the Greensburg tornado was...it started off as just a little guy, doing some weak tree damage as it crossed this road.

And even a few minutes later it still didn't show signs that it was going to become a monster and I never could of dreamed of what was in store for the rest of the night.

To me it's just fascinating to think of the processes that took place for the tornado to become what it did because when it first started out...it wasn't much.

 

[Lanny Dean]

I know what you mean Darrin. It still amazes me that none of us were killed that night. I never would have thought that when we Randy and I were sitting down there with you and Dick wondering if things were going to "go" that it would produce such a monster. Much less sitting back year and a half later questioning if it(GT) was bigger/stronger than we thought....BTW I did not mention you in the original thread and I should have as you were also taking photos. Kuddos to you and Dick for giving Mike the info and pictures he needed for this paper, without you guys who knows where we would be.

 

[cdcollura]

Good day all,

This is a fantastic thread and the paper was awesome.

One point is that the Greensburg storm was quite an awesome example of a supercell storm that is rotating so hard and so big, that you basically have a mesocyclone with strong tornado velocities, with a hurricane eyewall like structure, including an "eye" (vortex hole).

Now, with all this data on the Greensburg storm, can we also look at other storms, such as May 22, 2004 (Hallam, NE), May 3, 1999 (OKC), and even May 23, 2008 near Quinter, KS. All these storms had large mesos, and produced multiple tornadoes, some exceptional. On the Hallam storm, I clearly see a vortex hole and eye (surrounded by high reflectivity) with the tornado "hook" on the southside of the storm.

Even worse, such a strong meso, reaching at or close to the ground, can cause wind damage outside any tornado - Imagine getting caught in the RFD of such a storm :-(

I remember with the Quinter storm, the entire storm was rotating at higher levels, showing the meso was very fast and large. The wedge and satellite vortices, strinkingly similar to those shown with the Greensburg storm, would form and rotate around the southern / SE side of this meso, so I am thinking some kind of streamwise shear might also be at play. The Quinter storm also had a violent RFD, well over 100 MPH.

I assume supercells of this magnitude are rare and only small amounts of their mystery are starting to be discovered about them now.

 

[afischer]

I was glad to see Mike and Les Lemon come up with as outrageous instability parameters as they did in their paper. The 00Z Lamont OK RAOB had a very moist boundary layer (100mb ML dewpoint of 66-67F) about 1.75km deep... and the deeply mixed 00Z DDC RAOB was relatively cool in the mid-levels (e.g. 700mb temp around 7C). The ~700mb thermal ridge probably began rebounding northeastward near dark, but even so... combine the retreating strongly moist layer under modest capping aloft, with increasingly elevated terrain, and you get--as they showed--extreme instability, with very strong low-level instability... and persisting all night no less per the 12Z DDC RAOB. Ridiculous set-up after dark, and luckily not something that happens very often!

Edit: The CAPE vs. 0-1 km SRH from Figure 5 - unbelievable how extreme those values were in the environment that night.

 

[Rob Wadsworth]

Good day all,

This is a fantastic thread and the paper was awesome.................I assume supercells of this magnitude are rare and only small amounts of their mystery are starting to be discovered about them now.

One begins to wonder if our ability to account for this kind of storm phenomena has been a result of a better capacity to collect and understand this data. Do we know if any of these events in time past were similar? Or are we seeing the possibility of 'super tornadoes' numbers rising? It may make an argument for global warrming - which I'm not convinced of or do I believe it is the case or fact. Are the numbers of these occurrences increasing - do the stats verify it - or is it better met collection and reporting?

 

[John Farley]

One begins to wonder if our ability to account for this kind of storm phenomena has been a result of a better capacity to collect and understand this data. Do we know if any of these events in time past were similar? Or are we seeing the possibility of 'super tornadoes' numbers rising? It may make an argument for global warrming - which I'm not convinced of or do I believe it is the case or fact. Are the numbers of these occurrences increasing - do the stats verify it - or is it better met collection and reporting?

Before Rob posted this question, this thread had already sent me looking for information again on the Tri-State Tornado. According to the Wikipaedia article on it, it reached a path width of 3 miles at one point. People did not recognize it as a tornado because it was so wide. Although there was none of the modern data that could ever tell us, it certainly seems to me like a candidate for the kind of thing we are discussing in this thread. Another example might be the 1896 St. Louis tornado - the costliest ever and second-deadliest tornado. It reached a path width of a mile, and is probably the closest case there has been to something like the Greensburg tornado going through a major city (although it is only rated F-4, unlike the Tri-State which was F-5).

BTW, has anyone seen an online version of the Doswell et. al paper on the Tri-State Tornado documenting that the damage path was continuous and probably about 15 miles longer than previously believed? I heard his talk last year at John Logan College, but have not seen the complete written version of his paper, if indeed it has been completed.

 

[Adam Lucio]

That was a fantastic read, one that will require me reading it a couple more times to ingest everything. The thought about these "mini cyclones" makes you wonder just how powerfull these storms can become. Those radar shots were awesome and I almost had a chill comprehending the true power of that monster.

Sort of makes you wonder...is that as strong as one of these storms can become...or if conditions are tweeked just slightly...what is still possible?

I guess well have to wait for the next one in which to obtain new data from

 

[Andrea Griffa]

Amazing paper!!
I've got a question,Mike and any other who wants to answer: basically, as we are not able to understand if TC extends to the ground, so far, we could have at least a vague idea of it, if there would be something like a damage survey of the Trousdale tornado path.

Does anyone know if the damage survey of the Trous Tornado has been conducted, just to make a comparison between the TC and the path?

 

[Brian Stertz]

My guess is that it crossed a boundary and the LLJ kicked in and this is why it transitioned so quickly from a typical Kansas tornado to one that will go into the history books. It had a great look the whole time, but you could tell that something happened in a big way structure wise as it moved from Comanche Co. into Kiowa Co.