Greensburg, KS Tornado Track Twirl

UPDATE:5/17/2007 7 AM: I woke up in the middle of the night last night and wondered if maybe the "appendage" which gets wrapped into the Greensburg supercell and tornado was an outflow boundary (see Phoenix Dust Storm blog for a tutorial on OB's). If there were high winds at the "bow" of the outflow boundary, that would explain the velocity data, which wasn't really a couplet, but just high winds, and the reflectivity data, which didn't show much. I had cut off the radar data at 30 dbZ on the loop below, to cut out the clutter, but I might have also cut out the signs of an outflow boundary. I'll look up some additional radar data and get back to you on this one.

ORIGINAL BLOG: 5/16/2007:

The NWS has released their initial track analysis of the Greensburg F5 tornado, and as I pointed out the following day in my video blog, that the storm on radar appeared to be "rotating into itself", which I had never seen before. It turns out was actually two large tornadoes. The track from the first twister loops counter-clockwise inwards while weakening, then the second tornado drops down.

I'm no tornado track expert, but I've never seen this before. The 1999 Oklahoma City Tornado, oft-compared against the Greensburg F5, did not have a curly track, though it did begin to curl cyclonically (counter-clockwise) near the end. In theoretical conditions, the tornado should track from southwest to northeast but curve slowly cyclonically with the storm. Nature doesn't usually provide these perfect conditions; perhaps that fateful night in May, it did. If you've ever seen something like this, please let me know. I've looked at various tornado track graphics on the web and haven't found anything similar. Taking another look at the radar animations below in an annotated video blog, I find something interesting.

I wonder what effect the velocity couplet to the west had on the Greensburg supercell. It seems that, when that mesocylcone (or whatever it was) merged into the supercell, the second large tornado formed, and I wonder whether that is coincedence. But hey, I'm no radar expert, I just work here. I'd love to hear from any chasers or radar experts out there. The blog from the radar operator at the NWS that night did not mention the second velocity couplet, though he confirmed that the storm was "the most steady-state cyclic significant tornadic supercell I had ever seen."