2013-05-31 EVENT: KS, OK, MO, IL

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Jeff Duda

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Skip, that video is top-notch! I can tell you poured over video and data for hours to produce this, and the results speak for themselves. Well done. I think with some condensing (for time purposes) this video could become an excellent educational video for use in spotter training or just general storm chasing training. You should consider contacting some WFOs about it and see if any would like to use it.
 
Jul 30, 2011
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Excellent video skip, I started it up intending to breeze through it really quick and cache it for a later but found that I couldn't turn it off and went the whole way through. Well done.
 
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May 25, 2012
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Skip, thanks for putting so much time into these analyses. Incredibly valuable. Now that you've spoiled me, I'm going to make a request for version 3. :)

Is there enough data fidelity (temporal and spatial) to support tracking/interpolating individual subvortices within the larger grey tornado track? These could appear as darker grey regions to indicate higher wind speeds. Alternatively, recoloring the grey track with a gradient to represent absolute wind speeds would also be really interesting. Seeing this tornado sub-structure animated on the map you've already developed would be mind blowing.
 
May 1, 2004
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That data exists from the mobile radars, so it's certainly possible. Somebody just has to sit down, piece it together, and format it. That data isn't available to the public though, at least not yet, while the researchers work with it.
 
Jan 14, 2011
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In response to a frequently asked question of why I chose my positioning and route of travel on May 31, 2013, tonight I put together this map which explains it. Perhaps this will clear up some of the confusion. Click on either the link or the thumbnail to view the full size image.

ae38e6fc7746b7b6a297aebb9286ee57.jpg

Full size:

http://stormhighway.com/may312013/elrenotrack2015.jpg

In the time that has since passed, I've realized that one of the big mistakes I made was missing an ominous warning sign: the very (unusually) wide rain-free gap between the tornado and the forward flank precip core to the north. The storm's forward flank core never deviated from its eastward track. This is what I've come to call a "yo-yo" effect, where the tornado/hook stretches far to the south, then snaps back north. If the storm had been tracking southeast like I had expected, then the forward flank precip should have also moved farther south and started to overtake me. It never did, I was in clear precip-free air the entire time west of 81.

I hope this is helpful and I would like to hear comments and questions.

EDIT: I discovered while watching Tim Marshall's 2014 Chasercon presentation that he already coined the 'yo-yo effect' term to describe an extended hook that snaps back to the north.
 
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Nov 18, 2006
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That actually makes a lot of sense, Dan. I believe the Bowdle storm did this same thing. Definitely something to watch for on future chases.
 
Apr 18, 2010
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The yo-yo description reminds me of the 5/20/13 Moore tornado. I remember thinking the appendage was way the hell away from the ff, and the radar animation shows it kind of pulling itself closer as it neared where I-44 turns north towards OKC which corresponds to the temporary northward jog in the survey path, not as dramatic as El Reno's turn. I wasn't on Moore and I'm not sure from the videos if there was any wide rain-free gap that correlates as Dan describes, but that was the first thing that came to mind when I read that description.
 
Aug 16, 2009
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Nick I know exactly what you mean. I screen grabbed the radar when I noticed that in the storm.



At first I didn't think there was any way that that was the updraft base. But the more the storm matured, the more I realized there was some wicked speration of updraft and FFD. You could almost visualize the rain free base, tornado, and RFD from just looking at the radar.

 
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Jul 5, 2009
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In response to a frequently asked question of why I chose my positioning and route of travel on May 31, 2013, tonight I put together this map which explains it. Perhaps this will clear up some of the confusion. Click on either the link or the thumbnail to view the full size image.



http://stormhighway.com/may312013/elrenotrack2015.jpg

In the time that has since passed, I've realized that one of the big mistakes I made was missing an ominous warning sign: the very (unusually) wide rain-free gap between the tornado and the forward flank precip core to the north. The storm's forward flank core never deviated from its eastward track. This is what I've come to call a "yo-yo" effect, where the tornado/hook stretches far to the south, then snaps back north. If the storm had been tracking southeast like I had expected, then the forward flank precip should have also moved farther south and started to overtake me. It never did, I was in clear precip-free air the entire time west of 81.

I hope this is helpful and I would like to hear comments and questions.
Dan, thanks for putting this together and for continuing to share insights from this event over a year and a half later (which I was not on, by the way, flew home that morning, which I will probably always regret.... )

I have two questions:

1. Since the objective of your post is to explain your route and positioning, I wanted to ask a clarifying question raised by your map. You have the right third marked "tornado clearly visible." This includes the area where the tornado was moving northeastward, it is south of you, yet you still continued east. During this time, did you realize it was going to cross your path and you were trying to beat it, or did you still not realize the tornado's motion at that point?

2. The "yo-yo" effect is very interesting. This is my first time hearing this concept. Have you (or anyone) seen this written about previously and is it a recognized aspect of storm evolution, or is it an observational anecdote at this point? If it is the latter, it would be interesting to pursue. On a related note, you say that you should have paid more attention to the FFD movement. I always thought it was NOT a good idea to focus on FFD movement, because there can be expansion/contraction of the precip that is not correlated with storm motion and can be misleading? Or I guess maybe the answer is that you wouldn't read too much into it if it was moving southeastward because it could just be expansion of the precip as opposed to storm movement, but the fact that the FFD was NOT moving southeast is enough to tell you that the storm could not be moving southeast?

Thanks in advance for your insights!

Jim


Sent from my iPad using Tapatalk HD
 
Jan 14, 2011
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During this time, did you realize it was going to cross your path and you were trying to beat it, or did you still not realize the tornado's motion at that point?
James, when the tornado began making its turn, it was obscured from view by the rain. From my vantage point, I did not realize what was happening until well after crossing Highway 81. I was already at least 3/4 mile east of 81, eastbound on Reuter, when I recognized what was happening. At that point, I could see that the rain curtains were moving at tornadic speeds and were actually inside of/part of the tornado, not just the 'benign' outside rain wrap. There was no time to turn around and head back to 81 to go north. Turning north on Alfadale or Radio (my next north options) would have just kept me in its path (not to mention necessitating slowing down to take a 90 degree turn), so the only real option I saw was to go east. In retrospect, I could have turned around and escaped westward, but at the time I don't think I would have taken the chance of stopping and doing a k-turn with that bearing down on me.

2. The "yo-yo" effect is very interesting. This is my first time hearing this concept. Have you (or anyone) seen this written about previously and is it a recognized aspect of storm evolution, or is it an observational anecdote at this point? If it is the latter, it would be interesting to pursue. On a related note, you say that you should have paid more attention to the FFD movement. I always thought it was NOT a good idea to focus on FFD movement, because there can be expansion/contraction of the precip that is not correlated with storm motion and can be misleading? Or I guess maybe the answer is that you wouldn't read too much into it if it was moving southeastward because it could just be expansion of the precip as opposed to storm movement, but the fact that the FFD was NOT moving southeast is enough to tell you that the storm could not be moving southeast?
When the tornado was at its southernmost point, there seemed to be an abnormally wide separation from the hook/meso and the FF precip. There's always some type of gap there (part of the vault region) but in this case, it seemed exceptionally wide.
 
At just over 4 mins in, you can see us heading east past the videographer, and then he is just behind us at an intersection (we're in a GMC SUV). It then looks like they were behind us, in a small convey until US81 - at this point I made the call for us to continue east, remarking 'I don't know why you'd go south'...I have always wondered what it would have been like...I'm glad we didn't!
 
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Jul 5, 2009
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That was an incredibly intense video. I wonder why it took nearly seven years for him to post? (Wow, can’t believe it has been that long...)

I was not there, have not watched any El Reno video for years now, and am unsure where the storm was in its evolution during this video, so I have a couple questions. That first circulation that appears to have crossed to the east side of 81 at a little over 9 minutes - was that what ultimately became the main tornado / wedge, or was that a satellite? Then when they were facing into the debris field, was that the edge of the main circulation / RFD (which I know in this case essentially was part of the tornado) or was that a satellite circulation they were in?

Can’t imagine it was too smart to face into the debris, I know they didn’t want the car to roll but they were risking serious injury from a smashed windshield. They would have been better off facing the back of the car into it, at least they would be further away from the glass and not getting it in their faces

Good to have some activity on this thread after so long, still the most fascinating event in my opinion, despite the more recent SLT incident, which is interesting for the chaser impact but in my opinion El Reno is far more meteorologicalically interesting, both for the storm itself and the conditions that gave rise to it.
 
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James - the first circulation - I believe this was the circulation which pushed Bettes off the road - I'm not sure if it was the suction vortex which went on to the Twistex crew - perhaps @Skip Talbot could comment as he's undertaken an extensive analysis, with others. Overall, though, I think you might class it as suction vortex, as opposed to the 'main' tornado - for much of the period following that crossing the highway they are within the broader tornadic circulation.

The second part, with debris - I *think* this is another embedded suction vortex/whatever it might be classed as - it was around this time the tornado was really expanding too - you can see when they then face NE that the whole mass has, effectively, cloud material at ground level, which it didn't a few mins earlier before it crossed 81.
 

James K

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@Dan Robinson:
Whoa that's a pretty intense vid!

---
I went back & read through the whole thread (since it was posted well before I ever joined here)...and just .wow. reading it. Its all like a bit of history saved right here on ST.
Kinda sad that some of the pic's & links no longer work tho.
 
@Dan Robinson:
Whoa that's a pretty intense vid!

---
I went back & read through the whole thread (since it was posted well before I ever joined here)...and just .wow. reading it. Its all like a bit of history saved right here on ST.
Kinda sad that some of the pic's & links no longer work tho.
If you fancy a read of our chase experience, with a few pics, feel free to have a look at May 31st report
 
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May 1, 2004
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That was an incredibly intense video. I wonder why it took nearly seven years for him to post? (Wow, can’t believe it has been that long...)

I was not there, have not watched any El Reno video for years now, and am unsure where the storm was in its evolution during this video, so I have a couple questions. That first circulation that appears to have crossed to the east side of 81 at a little over 9 minutes - was that what ultimately became the main tornado / wedge, or was that a satellite? Then when they were facing into the debris field, was that the edge of the main circulation / RFD (which I know in this case essentially was part of the tornado) or was that a satellite circulation they were in?

Can’t imagine it was too smart to face into the debris, I know they didn’t want the car to roll but they were risking serious injury from a smashed windshield. They would have been better off facing the back of the car into it, at least they would be further away from the glass and not getting it in their faces

Good to have some activity on this thread after so long, still the most fascinating event in my opinion, despite the more recent SLT incident, which is interesting for the chaser impact but in my opinion El Reno is far more meteorologicalically interesting, both for the storm itself and the conditions that gave rise to it.
Allan Gwyn's shots were hugely helpful for the crowd sourced El Reno Survey project. They've been up there for years, but yes, I believe he just now also posted them to YouTube.

The vortex crossing 81 is almost surely the same that struck Bettes and crew, and likely Twistex a few minutes later. It's a subvortex embedded near the center of the ~2.6 mile wide parent tornado, not a satellite on the rim or outside. The subvort was about the size of a "large, regular tornado". It's my understanding that what we'd normally call the tornado cyclone (or mesocyclone maybe) scale circulation intensified at ground level to the point that it was the effective tornado. What Josh Wurman calls the MVMC (multiple vortex mesocyclone). The more conventional tornado sized vortices within were acting like legit subvorts though. They had looping motions, erratic at times, and there were several of them embedded within the large parent circulation.

The blast of wind and debris impacts that follow in Gwyn's video are likely from an intense rear inflow jet feeding what was becoming a very visually apparent wedge. The "ghost train". I think they were correct to nose into it. Such winds can roll a high profile vehicle, and the windshield is laminated. It would likely crack, but the laminate should hold the glass in place. Whereas if the side or rear windows go, then you've got flying glass, which is what happened with Dan Robinson on the same part of the storm a few minutes later, and with Adam Lucio on the Wayne, NE EF4 a few months later. They both lost their back window. Chasers might dismiss this as RFD, but these winds are of tornadic intensity, directly feeding into the core vortex, and often included as part of the tornado track when the NWS conducts a damage survey. For all practical purposes, this is part of the tornado. And Gwyn was likely inside of the tornado itself, experiencing winds of tornadic intensity within a circulation, from about the time he turned south on 81 to until that blast of debris let up.

Gwyn's position at the time is shown here plotted with with MPAR velocity. You can see he's on the edge of some super intense inbound velocities: the jet feeding that tornado. To the south there is a huge swath of straight line RFD too, and if you look closely there's a small satellite that goes by to their south, embedded within the straight-line RFD. Pretty crazy. This video is a harrowing example of what we've been trying to stress to chasers about not racing south across the path of the RFD region on giant HPs.


gwyn.jpg
 
Jan 16, 2009
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He says the tornado is going south and he was right when he turned on 81 but this video shows the moments it started it's turn back to the NE again. As it was widening and becoming a wedge you see a skinny visual satellite but there is a larger area of circulation above them. I feel this is the moments it started to become it's widest. The debris coming at them I think is actually a spin up from the widening area of circulation. This is definitely a very dangerous situation and luckily he made the correct call to back up on 81 as it did what he was going to do. These lessons I used later in the year with the start of EF4 Wayne. What a great video to learn from.

Path.jpg
 
Jul 5, 2009
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The vortex crossing 81 is almost surely the same that struck Bettes and crew, and likely Twistex a few minutes later. It's a subvortex embedded near the center of the ~2.6 mile wide parent tornado, not a satellite on the rim or outside....

... Gwyn was likely inside of the tornado itself, experiencing winds of tornadic intensity within a circulation, from about the time he turned south on 81 to until that blast of debris let up.
Thanks for the additional analysis and clarification Skip. As I was reading the first excerpt above, I was thinking to myself, "if the subvortex was NOT on the rim and it was near the center, then doesn't that mean Gwyn was actually inside of the larger tornado?" And sure enough, that's exactly what you said later in your post.

What an incredible situation.