"Reverse" Tornado Handoffs

[Mike Hollingshead]

The Dupree SD storm from June 16th got me thinking about something I noticed on this one. It's hard for me to come up with other similar examples. I think more than anything it must have just been the orientation of things more than it actually being "reversed".

We've all seen the normal way of handoffs. First tornado occludes west in the rain and new circulation develops out ahead, maybe at the apex of the old rfd cut. Sometimes the two are quite close and can appear as one damage track.

What happened on Dupree was a bit different. The most significant tornado of the day was pretty much the first full fledge tornado. It turned into the wedge or near wedge deal. It barely moved at first. Then it began to steadily push eastward and curl north. It moved ahead of where the next tornado would form, another wedge. It doesn't seem very often such a hand off takes place with the old one dying ahead of the next beast.

But the more I thought about the orientation to do all that, the more I realized that stationary storm was just turned and wrapped so much that the apex for the new area was just ending up behind the first one. Like the very stationary and wound up nature was just allowing the occlusion to get flung around ahead of the next tornado. After those and then during the next shorter lived ones I remember noting how odd the front of the storm structure looked. Looked like you just had this big open area wrapping way back west and then southwest behind the leading rfd/base. So it still was having that very torqued orientation of things compared to more normal processes.

Just thought it was quite interesting. Any others anyone can think of acting like that having the significant hand off ending up behind the previous one? Not just a different tornado that forms while a bigger one is behind it, but a shrinking previously main tornado ending up ahead of where the next main big tornado forms. I went through all the tornadic storms I've seen in my head and was failing to come up with something similar. It really showed how one could have very long continous damage tracks if it was doing stuff like that. More so than just your typical close handoff.

 

[Shane Adams]

Can't be sure, but from our location on April 22 it seemed as if the second tornado near Groom developed NNW of where the first one roped out just seconds before. As the second one roped out, it too got shunted well south-southeast of the next developing circulation.

On May 3, 2003 near Haskell, TX we saw a new tornado develop west of an ongoing one, buried in wrapping rain, while the eastern one was in clear air. Another tornado was also ongoing further east of the original one, also in clear air.

 

[Simon Brewer]

I haven't looked at all the data from the Dupree,SD storm, but when I study supercell storms in hindsight, especially when looking at storm-relative-shear, I first focus on storm motion. Storm motion can be tricky especially when a person may be looking at base reflectivity alone. A great example would be the Sharon/Attica/Harper,KS tornadic supercell of May 12, 2003; by looking at base reflectivity on radar it would appear the storm motion was east at 10-15 mph, but each mesocyclone was nearly stationary. The FFD of the storm only moved on base reflectivity due to the process of occlusion, but each mesocyclone was virtually stationary from start to finish, so when analyzing a hodograph I placed the storm motion at 0. The Jerrell,TX tornadic supercell is another example of a supercell, which moved due to the process of cycling.

To understand the Dupree,SD storm it would be best to begin studying the direction of movement of each mesocyclone and then determine the process of new mesocyclone development. It might be helpful to look at some examples of cyclic supercells that had a stationary or maybe northwesterly storm motion. I think there was a supercell in the Texas Panhandle in 2007 that acted in a very similiar fashion to the dupree storm until the outflow from the FFD finally undercut the updraft and forced the storm eastward.

Simon