Tornadic Circulation vs RFD in El Reno Tornado

[David Williams]

MODs: not sure if this is the right place for this discussion.

I, like many others, was caught at El Reno rd and highway 81 when the tornado began to expand and turn north. I have been trying to piece together my experience, and I was hoping to get some input from the more experienced chasers and from anyone that had a better view of the storm than I did from right under it. After waiting my turn to go south from El Reno rd onto 81 I was only able to drive for 10 or 15 seconds before I noticed through the rain a large vortice moving ne toward me from only a few hundred feet away. I, and the other drivers/chasers around me, quickly put on the brakes and went in reverse to let the vortice pass in front of us (I'm not sure if this is the same vortice that hit the Tornado Hunter vehicle but I did notice the next day when I drove through the damage path that he was very close to my position at that time.) Many of the other vehicles stopped after the vortice passed in front of us on the road. However, recognizing the transparent rain bands/condensing tornadic circulation and debris in the air I knew we weren't done with the tornado yet. So, I drove south as fast as I could. I passed a parked police car and what looked like a Dominator; however, I couldn't look too closely because a power line was down in front of me and I had to drive into the median to get under it. With the highway clear, I blasted south. Unfortunately, I also got blasted by some intense wind from the west. In a matter of moments debris was flying across the road and my windows were blown out. Fortunately, I made it out of the RFD after about a 1/2 mile with only a scratch on my cheek.

So, my question is where did the tornadic circulation end and the RFD begin? I understand that this question may not be accurately answered because of the nature of this rare beast. But, I am trying to wrap my head around what happened. I clearly got caught inside the tornado at El Reno and 81 because this is the exact time when the tornado expanded and made its northern turn. Also, I had to reverse (move north into the larger tornado) in order to avoid getting hit by a large vortice. The wind was strong during that time; however, it wasn't until I passed the cop car and downed power line that the wind started really moving (granted I was able to accelerate faster but the force was a noticeable increase from the west) and this is when the debris very much like Brandon and Brett drove through started flying across 81. Anyone that drove 81 that day or the next would have noticed the mile or more of debris caught in the fence and rail guard along the road.I have watched many of the videos in the reports section, and many videos show what looks to be a clear slot far south of the tornadic circulation. Anyone with any feedback, ideas, or stories please chip in.

 

[STexan]

I was sort of wondering the same thing. Is there a map yet of a "damage path"? I've seen several maps of the path of what I believe to be the main meso feature, but have not seen a map of actual tornadic ground paths (damage). The El Reno meso was a unique system as it was VERY close to ground level for most of it's life cycle and it's hard to tell where a tornado was underneath and not. I've seen the "record breaking" stats of this being the widest tornado but I'm not yet prepared to buy into that notion unless what appeared to be a meso making contact with the ground was actually a wedge tornado.

 

[mkavulich]

After waiting my turn to go south from El Reno rd onto 81 I was only able to drive for 10 or 15 seconds before I noticed through the rain a large vortice moving ne toward me from only a few hundred feet away.

I don't want this in any way to sound rude or condescending, but I've seen it a lot recently and would like to dispel confusion.

There's no such thing as a "vortice". It's a vortex. The plural of vortex is vortices. Isn't English great!


Edit: I suppose it's only polite of me to try to answer your question as well.

I'm not sure what the official policy is on separating the RFD from the tornado damage path. In many cases (as it appears with this one) there is not a distinguishing line where the surface inflow ends and the RFD begins. Clearly there is a difference; for instance, this video seems to show the RFD, as it is all blowing west and not flowing into the tornado, and obviously the Weather Channel team was hit by the tornado proper. But somewhere in between them the difference would likely have not been so clear. I'm not sure if there are any NWS surveyors on this forum, but I hope one of them can weigh in.

 

[David Williams]

There's no such thing as a "vortice". It's a vortex. The plural of vortex is vortices. Isn't English great!

Ha! I understand your need to correct. Oddly enough, I actually looked the word up to be correct and saw vortex and vortice in the dictionary; but, I went with "vortices" anyway because I thought it sounded better and didn't think anyone would notice.

 

[William Monfredo]

Honestly, I don't know if you are going to be able to tease out those details of where an rfd stops & a tornado begins. But, I can tell you that it's highly subjective when there's grant money involved & a very limited sample to declare the largest tornado ever. I worked at OU.
It's kind of embarrassing, actually, given that so many other powerful tornadoes over the years have simply never been remotely sensed with dual polarization on mobile platforms. And that's why I found it misleading for TWC to talk about time frames between violent storms in central OK this May compared to other years. It's apples & oranges.
The best solution, if improbable, is for you the chaser, to have similar equipment, and then make the judgements yourself. Then you & OU could hash it out. :>)

 

[Windshear Kear]

There was a damage path drawing on Norman's NWS site. It was on the front page for a week, but you might have to search a bit for it now.

 

[Jeff Snyder]

Honestly, I don't know if you are going to be able to tease out those details of where an rfd stops & a tornado begins. But, I can tell you that it's highly subjective when there's grant money involved & a very limited sample to declare the largest tornado ever. I worked at OU.
It's kind of embarrassing, actually, given that so many other powerful tornadoes over the years have simply never been remotely sensed with dual polarization on mobile platforms.

What grant money are you speaking of? The NWS performed the damage survey and found a massive swath of damage The NWS provided criteria that they thought to be appropriate for delineating the RFD from the tornado, and data from a radar was used give estimates based on those criteria. Our group has said nothing of the width -- I just provided the data that was asked for. Anecdotally, it's common for these exceptionally large tornadoes to be associated with intense RFDs, and there's often ambiguity regarding where the tornado "ends" and the RFD "starts". Heck, it's difficult to even figure out what IS the tornado in these cases. On 31 May 2013, there's one well-defined break in the strongest flow that acts as the only logical, in my opinion, visual queue as to where the tornado "ends". The damage was very widespread, and the track is based on the areas of damage first with some radar data used to "shrink" the damage path and help pull out what was RFD and what was tornadic flow.

As for the "largest" business... The NWS will base that off of the tornado events in the Storm Data database. As such, this one technically is the largest in the database (assuming that preliminary width holds when it's officially submitted). Again, there probably have been larger tornadoes in the past, but the NWS is going to go by NWS records obviously.

 

[Dan Robinson]

For what it's worth, I can confirm that the mapped El Reno tornado damage swath matched up to what I observed visually at the intersection of Evans Road and Reuter Road. The east edge of the wedge's condensation enveloped the intersection and two trees nearby just to the east. An inflow jet was also visible immediately to the east of this. The RFD at this location was a distinct shift out of the west-southwest, coming around and cutting off the inflow jet. I observed damage from the RFD well to the east of the mapped tornado track (including to both me and my car).

 

[Caleb Chevalier]

I don't have the link on me, but there were a couple satellite photos published that show a massive scar on the landscape SE of El Reno. The nature of it would indicate to me that a very wide tornado was on the ground, not just a few vorticies dancing around a meso.
The damage path illustrated by OUN matches up nicely with the satellite image as well.

 

[Shawn Schuman]

I don't have the link on me, but there were a couple satellite photos published that show a massive scar on the landscape SE of El Reno. The nature of it would indicate to me that a very wide tornado was on the ground, not just a few vorticies dancing around a meso.
The damage path illustrated by OUN matches up nicely with the satellite image as well.

Via Brad Panovich on Facebook.

 

[Patrick Marsh]

Honestly, I don't know if you are going to be able to tease out those details of where an rfd stops & a tornado begins. But, I can tell you that it's highly subjective when there's grant money involved & a very limited sample to declare the largest tornado ever. I worked at OU.
It's kind of embarrassing, actually, given that so many other powerful tornadoes over the years have simply never been remotely sensed with dual polarization on mobile platforms. And that's why I found it misleading for TWC to talk about time frames between violent storms in central OK this May compared to other years. It's apples & oranges.
The best solution, if improbable, is for you the chaser, to have similar equipment, and then make the judgements yourself. Then you & OU could hash it out. :>)

If you use the radar data from multiple radar groups (not all from OU), the wind speed should result with an EF-5 tornado and a width of 2.6 miles. If you remove the use of the radar, the tornado width is somewhere in the vicinity of 3.2 miles because the EF-0 damage extended that far. You can't use the radar to rate the intensity based on the Doppler winds and not use the radar determined width; nor can you use the radar's width and ignore the winds. It has to be both or none.

 

[Kent Heiderich]

There was a damage path drawing on Norman's NWS site. It was on the front page for a week, but you might have to search a bit for it now.

There is this page that list other tornado events that day & a phased array radar loop of the El Reno storm. http://www.srh.noaa.gov/oun/?n=events-20130531

 

[William Monfredo]

Wouldn't it be interesting if the widest tornado designation held up, but after the 60-day review period, the EF-5 status didn't hold up? It's entirely possible that top-ranked damage will not be found (if there's been some, I'd like to know), and that NWS lowers the tornado rating a couple of notches. The head of the NWS and the warning coordinator at SPC are of the belief that there needs to be appropriate damage found at the ground, otherwise, additional information from mobile platforms are but an addendum. But, yes, you could say EF-0 damage extends a great distance. I'm more in favor of EF-1 as a starting point for width, though.

 

[Dan Robinson]

At the end of the day, if the tornado was measured at 2.6 miles with 295mph maximum winds using reliable instrumentation, its true intensity is EF-5 by simple definition, regardless of if NWS's hands get bound by the internal order to not consider the radar data. I was there, there was no EF-5 damage evident because the EF-5 strength portion of the tornado did not impact any of the sparsely-available DIs in the area. Even tree DIs were sparse. What if there had been no structures? Then we'd be looking at EF-0 or EF-1. I'd think the true strength of the tornado would be important to climatology when assessing the threat of similar environments in the future. It's interesting that the bulk of the scientific/research community supports the use of the radar in the rating, while the NWS's stance (and ultimately the final rating) is more tied to bureaucratic directives (from, what it seems, possibly a single individual at the head of the NWS). In other words, if a couple of NWS higher-ups say so, it will end up being an EF-3, while everyone else knows what the tornado's intensity truly was.

 

[Kent Heiderich]

Thanks Dan. This was truly a unusual storm. Watched the "Weather Channel" account of Our Dearly missed Tim Samaras. According to the weather channel, Tim was found in the Cobalt & Paul Samaras & Carl Young were found 1/2 mile from the Colbalt in opposite directions. Not quite sure what that means as to the tornado circulation, but it says forces were at play that need future understanding & study. Damn sure a EF3 wasn't the only force at play that evening.