Wednesday, June 5, 2019

A merger of two separate long-track tornadoes in northeast Kansas on May 28, 2019 !

I wasn't planning on posting anything further about the Lawrence-Linwood tornado and the Silver Lining Tours (SLT) encounter with a separate rain-wrapped tornado, thinking enough has been said already.

However, the National Weather Service in Topeka today released an addendum to their original survey identifying and adding a new tornado (EF2) that was previously unreported in southwest Douglas County, Kansas.  This was the rain-wrapped tornado that struck SLT, rolling two of their vans, and was located at the time of the incident within the rain-filled rear flank downdraft (RFD) of the developing mesocyclone to its north that gave birth to the large Lawrence-Linwood tornado.

As I suggested in my prior post, this additional tornado was not a satellite tornado, but a separate tornado that had not yet been confirmed or reported previously.  It ended up merging with the developing large Lawrence-Linwood tornado, a complex and fascinating evolution and interaction.

Here's a map I constructed by putting together NWS Topeka and NWS Kansas City survey maps of the two tornadoes.  This shows the full tracks (nearly 43 miles total) and where the two tornadoes merged:

Roger Hill was kind enough to share his video with me privately, shot while SLT was retreating to the south away from the developing Lawrence-Linwood mesocyclone and what they thought was away from danger.  With Roger's permission, here's a panoramic image I put together from his video as they were pulling away to move south:

You can clearly see the visual mesocyclone to their west-northwest (at right), also the focus of several other chaser videos online.  But also notice the advancing rain-filled RFD coming up from their south (center of the image) that unbeknownst to them contained a hidden and unreported tornado that no one yet knew about.

Most spotters and chasers are taught to stay southeast of northeastward-moving mesocyclones (areas of organized rotation in supercell storms) to stay safe.  So, SLT thought they were doing the careful thing to head back south to Highway 56 and follow the primary mesocyclone from a safe distance.

Complaints and accusations online (Facebook, Storm Track, etc.) have focused on the question, "What was SLT even doing in the bear's cage?"  Well, that question kind of misses the point when the room becomes dark and you don't even know an additional bear's cage is there after you're already steering clear of the main bear's cage that you know is behind you.

The tornado merger in this case was very similar to the Hesston-Goessel, Kansas tornado merger I studied on March 13, 1990 that led to an EF5 tornado:

The difference is that the 5/28/19 merger took place hidden in rain within an HP storm, while the Hesston-Goessel supercell was a classic non-HP storm and very visible.  In fact, we might not have even known about this merger had SLT not had their encounter!

To my knowledge, this is the first time a merger of two separate medium or long track tornadoes has actually been documented within an HP supercell, although similar mergers have undoubtedly occurred but not been documented.  This case certainly deserves further study from several perspectives.

Thanks to meteorologist and severe storms expert Greg Stumpf for being astute enough to recognize the similarity to the 1990 Hesston-Goessel merger/interaction, and mentioning it on Facebook already several days ago.

- Jon Davies  6/5/19


Rick Schmidt said...

Thanks, Jon! This is very fascinating, especially since I was kinda close to it!

Jon Davies said...

Thanks, Rick. I really appreciate your sharing your photos via email earlier!

Unknown said...

Fantastic work guys. Would love to see more on this. I will need to go look but I may have video to submit if you guys are looking for it in the initial stages of the 1st tornado's development.

Robert Edmonds said...
This comment has been removed by the author.
Robert Edmonds said...

Just because the paths crossed in space, doesn't mean they crossed in time.

Jonathan Merage said...

Jon, thanks for analyzing this storm's conditions and evolutions between the separate circulations and clarifying precisely what happened. Almost immediately after I read of their unfortunate incident I grew increasingly concerned and confused as satellite tornadoes are not really known to occur a full 2 miles from the larger tornado; but your examination, analysis, and explanation sheds much light (for me) on exactly what took place. Quite fascinating!
I am just glad that Roger and Caryn are still out in the field powering through and conducting their tours to this very day.
Hope to see them around our neck of the woods today (CO), in good spirits and health!
-Jonathan Merage

Jon Davies said...

Thanks again for the comments, everyone.

Regarding the comment about paths "crossing", careful radar data analysis (time stamps and location) and ground survey (my own) show that the two circulations unquestionably came together around 6:05 or 6:06 pm CDT. The smaller southern tornado track (50-100 yds wide) goes right into the spot along a tree line ENE of Lone Star Lake where the the large Lawrence-Linwood tornado was forming and almost immediately widened to 1/3 to 1/2 mile wide (!), chewing through a forested area. There was no "crossing" of paths... they came together during the complex formation of the larger 2nd tornado.

Paul Knightley said...

Great write-up, as always, Jon.

I had a look around on YouTube - this video *may* show Tornado 1, early on in the video - certainly there is an interesting lowering, which the videographer concentrates on:

StormCchaser said...

Jon - I just stumbled onto this posting - a bit late. Thanks for the careful, and very interesting analysis of this unusual event.

John Moore