This storm possessed one of the best-defined shelf clouds I've ever seen, and it never produced any known gustnadoes. Gustnadoes are known to occur along the gust front, but I don't think the visual appearance of the shelf cloud has much to do with gustnado potential.
I think how likely you are to see a gustnado depends on the terrain - the drier the soil and the less the amount of vegetation the better. You'll be much more likely to see a gustnado over a dry, freshly plowed field than you would over a waterlogged grassy field. A lot of the gustnadoes I've seen have been along gust fronts that have raced out several miles ahead of the main storm.
My observations are the same as David's... I've seen many more gustnadoes along the RFD gust front or near/under the flanking line than anywhere else... As for the specific question, I would doubt that there'd be much connection between the rigidity of a shelf cloud and the gustnado potential, simply because I don't think they are governed entirely by the same processes.
Then you can have this situation.
June 9th 1993 here in Tulsa County , Creek and Wagoner we had 4 official tornadoes. These actually seemed more gustnadoes though.Spin-ups where occuring all over the place but only a few actually touched the ground
Here is part of the official statement
"Severe thunderstorms moved across northeast and east central Oklahoma
during the afternoon of June 9th. Widespread wind damage occurred with
the storms, and 4 tornadoes occurred within a few miles of Tulsa. A few
locations also received dime to quarter size hail. A fast moving line
of thunderstorms was responsible for most of the wind damage, and 3 of
the tornadoes occurred as this line of storms intersected a southward
moving outflow boundary produced by a severe thunderstorm north of
Here is some video I took during this , I didn't get to witness a touchdown just some of the spinning motion.
I've noticed the more turbulent, and sheared apart gust fronts usually pose the biggest threat of gustnadoes. Usually the more, "well defined" fronts that I've seen havent been associated with any gust nado production.
June 2 of this year I filmed a gustnado here at my work. The gustfront was moving into the OKC metro and as it got closer I started to notice the leading edge of the shelf was moving N.E. and the back end of the shelf was going S.W. (I hope I explained that good enough).
So I got the still camera we have here at work, went outside and this is what I filmed.
Here's a question for you great plains pros. What's the difference between a gustnado and a landspout? I thought they both typically occured under a gust front of some sort? Or is it that landspouts are more like waterspouts in that they typically form under a towering cumulus as opposed to a supercell?
Have you ever encountered RFD gustnadoes and supercell updraft penedent tornadoes at the same time? Do the gustnadoes ever move into the updraft region and become a full fledged tornadoes, or do they always move out away from the storm with the rest of the downdraft?