Looking for opinions on video of radar on this storm - Weak? Worthy of attention?

[Mike Darling]

{MODS - I apologize if I'm in the wrong category. I do know that events within 48 hours have a rule to go in Target Area. I worry this post isn't worthy of being in there, since my question here is whether it was a notable event, but seems for a more advanced crowd than the intro section. If a mod sees this, please let me know which category this should be in, and if I post videos in the future, if they should be separate threads or responses to this one.}

Anyways, I'm hoping to post videos once and a while of radar imagery, and hear other people's opinions on them. Here's my first:

http://www.youtube.com/watch?v=07Dy9qbxDv0 (For best quality, click the gear, select 1080p, then enlarge to full screen by double clicking video.)

(Alternatively, if someone really wants to load it themselves, level 2 data's still available at this moment at http://mesonet-nexrad.agron.iastate.edu/level2/raw/KDTX/ )

Michigan had practically no chance of a tornado yesterday, so I didn't set out to chase. I was driving 90 minutes way to pick up something in Adrian, MI. Along the drive, there were some nice clouds & storms to look at. Around 19:25Zulu, I pulled off the road, just a bit North of Adrian, to look at my phone's radar. A storm we had been watching seemed to be intensifying, and had a nice (non-rotating) wall cloud. Haven't seen our first tornado yet, and couldn't believe we were in perfect position for something that looked a little visually nasty, just by pure luck. Certainly not the worst storm I've seen, but it is the first one I've been able to both see in person and analyze on professional radar. (Just started w/ gr2analyst a few weeks ago.)

It has a few short lived purple pixels, and a defined velocity scan eye. Then, splits and falls apart. I think 3D volume explorer shows updraft & downdraft rotation, at the very low end of the scale. I think 3D volume explorer reflectivity shows updraft & downdraft rotation, around the 55dbz range. I think 3D volume explorer velocity shows signs of mesocyclone rotation within the storm, at the very low end of the scale.

Tomorrow I'll be getting archival data on thunderstorms that produced tornados to start getting more familiar with those images, but I'd love to hear from those more knowledgable & experienced than me on their thoughts on this storm.


I'm wondering if what's depicted in this video happens all the time and is so weak that without massive intensification would never develop a tornado, or if it was closer to having the potential to develop one if it hadn't fallen apart when it did. Basically, if you were in the field watching this storm, what would your thoughts be?

 

[Joshua Nall]

I don’t have much experience with 3D radar and other stuff, but I’d say that’s just an average none severe storm. If I was out watching it, would hope to get a little bit of lightning out of it, just from what I see on base reflectivity and srv. So it would be interesting if it was dusk and I could open up my shutter for 5 secs or so. I’d assume that many single cell type storms rotate a little bit at certain times in their lifecycle.

There are LP storms that produce tornadoes that don’t have much of a reflectivity signal to indicate there is rotation, but they look a bit different than this. This storm has an oblong shape and even has a slight bow to it at one point. Just based on my experience, all the storms I’ve seen on radar that developed a tornado, you could see it in the reflectivity. There would be a hook or an inflow notch, or evident rotation visible embedded in the different levels of intensity in the reflectivity.

I’m not sure what you mean by defined velocity scan eye, but I’m still learning too. Are you talking about a couplet? A lot of storms will show inbound outbound winds close together, but it is how they set up opposed to one another in a small area in relation to the storm and how the couplet moves as you loop it and how intense it is that would give you clues as to the tornado potential.

 

[Stan Rose]

Looking at the GR2 data it's not a very impressive cell; low-topped and not much vil. Does show some signs of weak rotation, not surprising since there was about 30Kts bulk shear that time/place and 0-3km helicity was maybe up near 100. Just not enough instability--CAPE was probably not more than 500 J/kg. The one thing it has going for it is that it is isolated, little to interfere with it. So worthy of attention? Not from the radar, but who cares? It's how it looks in person that matters.