I had a look at Old Blaggards Tornado and thought I start a new approach. Just so my mind doesn't fall asleep.
I simulated the Tornado vortex via an expanded very dense helix with a slight sine wobble. (See image tbasics) which is again the helixed to a slight degree
Biggest problem is that the density of the helix fizzles out at lower cloud densities see 1 and 2 and lighting the thing is a nightmare.
30 mins on making the nodes. 3 days lighting..
But a nice rope tornado and not one of the big ones maybe got a step closer.
In the moment the basic shape comes from a circle image and the ground thing is a doughnut.
I haven't tried yet to make the warper eat instead of the image Mr Lampposts reverse cone.
I tried that but couldn't displace it and went back to my approach.