"Rolling fog banks" reminds me of some Tri-State descriptions, "boiling, rolling clouds" or "barrels", perhaps spawned from low-hanging cloud bases and rain-wrapped? Not sure.Yeah, based on witness descriptions, several of the tornadoes appear to have had horizontal vortices at times. It's a shame there aren't more videos from that day because it sounds like many of the tornadoes underwent pretty fascinating evolutions. Some of the descriptions of the Saegertown-Centerville F3 (which was probably an F4, but anyway) make me picture something almost like Cullman. The Corry F4 expanded from ~150-200 yards to about 3/4 mile in the span of basically a few minutes. People described both the Atlantic and Tionesta F4s as being like some variation of "rolling fog banks." Some pretty interesting descriptions of the Albion tornado, too. One person said it very quickly grew and shrank multiple times, almost like the funnel was "breathing."
I'm always been curious as to what made Cullman's appearance the way it was when it was going through the city, at many times it lacked a clear condensation funnel and the interior structure of the vortex was sometimes visible.
The Albion tornado description is fascinating; could have been an optical illusion based on how much debris the funnel picked up or maybe it was undergoing vortex breakdown? Again, not sure.