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David Drummond is very fine, here's the thread

This animation covers one hour, from 2341Z until 0040Z, the period during which the UEX RDA was the luckiest RDA in the world. :-)

Regards,

Mike

BTW, this software is available at http://www.gibsonridgesoftware.com/grw88level2/
Click to expand...

Mike,
Never heard of that software... I've been putzing around with it and I really like it! I have been using IDV, which is a very powerful display program btw, but it's a pain if you (well, I) just want to look at level II data as it is a mega-resource hog. The GibsonRidge software is much easier to use if you just want to view level II data... Additionally, it has a storm motion vector that, assuming you provide a good motion vector, let you convert radial velocity to SR velocity via the application of that user-provided storm motion... I do wish I can apply a better basemap (with at least the interstates), but oh well...
 
Jeff,

I'd encourage you, if you haven't done so already, to join the author's forum and give some input as he is still developing the software. Rob Dale and a few others including myself frequent there and the guy who is developing it is very open and receptive to user comments and suggestions. So far he is doing and outstanding job bringing added features in without making the app a resource hog (especially the smoothing feature.)

As far as map features go, I've inquired about some sort of GIS integration, at least the ability to export a georeferenced geoTIFF file to use in GIS apps and viewers. Of course, being able to import shapefiles (similar to DAWS and NEXRAD3) would be nice as well.

Regards,

Mike
 
David and Melissa,

I finally have the KUEX (Blue Hill NE WSR-88D) images, with co-locations of your van on Clay County street shapefiles.

64fa444cb9a467d27a70cd65cea24c0c.png

The following three images represent the 0.5 degree ground-relative velocity plots at 002944 UTC and the subsequent two volume scans. I've annotated the salient features.

81d6e6b44036cb515eb518fb0ed785ab.png

2191d0babccceeb1b145a7047fefef87.png

46468f6ed9167fff3d8ede6bc03a512f.png

The corresponding 0.5 degree reflectivity plots.

2d42c120d3065f420e3b033192e146b3.png

3122e884ad226cdd621d790f0aefaa2c.png

557c70e07b548657714e92cfb551e50b.png

I've also ran the NSSL "Rotation Tracks" product

7d51e953c3b6aa0114ee9dc1b2b145a2.png

Finally, the 1.45, 2.4, and 3.3 degree ground-relative velocity images which followed the 002944 UTC 0.5 degree image

3e6c3873f94359bdd2b8c21260419ec1.png

1202d9a8f4b80443cf9935922ea8f070.png

9fc8da0527b914b961382c545cab8c3e.png

I'll provide my commentary in the next post.


Greg Stumpf
 
My take

Based on my knowledge and interpretation of the KUEX (Blue Hill NE WSR-88D) radar data, this is my best guess as to what phenomena hit the WX5TVS van.

First, it is clear that the main mesocyclone and possible large tornado passed about 2-3 miles to your NW and N, and that your van had an interaction along the leading edge of the RFD gust front.

Second, based on the velocity data above the 0.5 degree tilt at 002944 UTC, there is an anticyclonic Tornadic Vortex Signature with a delta-V exceeding 85 kts. This appears to pass just N of your location (within 1 mile). That anticyclonic vortex may have developed to the ground just after the 0.5 degree scan, since it appears in the next 0.5 degree scan just NE of Fairfield.

Third, there is an extreme RFD on the right (south) side of the low-level (LL) meso, with sampled ground relative winds at 115 kts at 700 feet above ground level (AGL).

My call:

You were definitely hit by a major RFD gust surge - probably as extreme as they get. The leading edge of the RFD was probably very turbulent, and no doubt there were probably multiple transient gustnado-like vortices that were just as strong as the RFD winds.

You might have also been hit by a developing anticyclonic tornado on the leading edge of the RFD surge, as indicated by the velocity data aloft. Video from the east looking toward your location would be helpful. Anyone?

You were not hit by the main cyclonic tornado of that storm, nor were you hit by a new tornado following a cycling of a new mesocyclone.

Other opinions are welcome. But in the end, glad you are alive!


Greg Stumpf
 
You might have also been hit by a developing anticyclonic tornado on the leading edge of the RFD surge, as indicated by the velocity data aloft. Video from the east looking toward your location would be helpful. Anyone?
Click to expand...

Wow, what an insightful analysis Greg! Do you mind if I use that when I am able to finally get a chase account of it up? I can confirm that we saw multiple anticyclonic vortices around the van at various points, so that would associate well with your assessment there. In fact I think I made a comment on video about seeing something anticyclonic which I recall at the time surprising me. I also think we may have seen the results on the ground of either the occluded meso, or the developing new one when we were further west. It was shrouded in rain and there was tremendous inflow into that area so much so that telephone poles were rocking on the verge of breaking, it was at that point we started east and found the trees down and things got worse.

You were definitely hit by a major RFD gust surge - probably as extreme as they get. The leading edge of the RFD was probably very turbulent, and no doubt there were probably multiple transient gustnado-like vortices that were just as strong as the RFD winds.
Click to expand...

So essentially, even though this wasn't the main tornado (thank god!) there were still "gustnado" vortices in the 115 knt range? That is more than enough tornado for me to experience in one lifetime! :shock:
 
From the video, it definitely appeared to be more RFD related rather than a true cyclonic, supercell tornado...

I've seen several anti-cyclonic gustnadoes in association with the rfd that did considerable structural damage and definitely gave me a scare.

Glad you guys are okay...there will probably be similar situations to this tomorrow and Sunday I bet.

Good luck to all who are chasing this weekend.
 
I've been in indirect contact with someone at the SPC who has viewed a much longer version of the video whom thinks he see clear tornadic vortices and we were in the beginning stages of a multivortex anti cyclonic tornado. We are lucky to have not come in contact with any suction vortices.
Whatever it was dirt, rocks, sticks, grass and glass hitting you in the face and back at 107 mph doesn't feel good. I'd rather not do that again.

If someone was out east with a video camera I'd love to see it. I would really like to know for sure exactly what dropped on top of us and why the windows blew out the way they did.
 
yeah that must not have been fun...

We actually ran into three people about 2 miles east of Hallam who were locals and abandoned their car for a ditch and were pelted by debris and hail...I would guess they were just on the south side of the gigantic wedge as it exited Hallam. Hopefully there will be some more photogenic storms this weekend.
 
yeah that must not have been fun...

We actually ran into three people about 2 miles east of Hallam who were locals and abandoned their car for a ditch and were pelted by debris and hail...I would guess they were just on the south side of the gigantic wedge as it exited Hallam. Hopefully there will be some more photogenic storms this weekend.
Click to expand...

Now THAT scares me after seeing some of the ditches around that town packed with all manner of debris. After what I saw last weekend I can say, at least for me, I would never leave me vehicle for a low lying area. I would either try to run or find a building. I know if it gets bad enough I would die either way but after looking at that I can say I think I would die sooner in a ditch than in my vehicle.
 
Absolutely right about the ditches Dave.

One of the things which really struck me yesterday as we toured the damage path from Hallam up to Bennet was the prescence of corregated metal siding in many of the ditches and riparian stream valleys in the area. I don't think I need to bring up any gory reminders of what would happen if someone got hit with something like that while travelling at 200 mph.

As I've been able to witness more damage over the years, the more my belief is reinforced that getting out of the path if possible is preferential to "lying in a ditch."

Regards,

Mike
 
BTW, this thread I will save on my computer, is TOO "historic" to loose it.

[semi OT]

Does Stormtrack think to keep a room in the forum with the most important topics saved there ? We are doing the same in Italy in our forum, so not to loose these precious threads.

[/semi OT]

:wink:
 
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