Posted this on Twitter but will copy over to here if anyone wants to chime in
I think some post-storm analysis is in order for this system, specifically looking at the lack of many tornadoes today. In Georgia/Alabama specifically, the question all week was “will deep convection form?”… and the answer to that was yes. Very deep convection formed across the warm sector and manifested as a strong QLCS, yet, *thankfully*, there weren’t many tornadoes.
This QLCS was ingesting inflow with high CAPE (>1500-2000 SBCAPE) and intense streamwise vorticity (ESRH >900!!).. overall an extremely environment (STP 9+).. we saw the line kink and saw mesocyclogenesis occur; there were several embedded supercells within the QLCS especially around 20-22z in west Georgia into Tennessee. These storms had *intense* inflows and appeared to be structurally sound; in fact, I witnessed 3 or 4 fully developed rotating wall clouds today and saw several weak & broad rotations on radar in these storms.
The one thing we didn’t see, which I would expect from a broken supercellular QLCS ingesting 9+ STP, was widespread tornadoes. It’s a great thing that we avoided having many tornadoes because these storms moved very quickly across densely populated areas. It is still curious, however, as to why we had such robust mesocyclogenesis with limited tornadogenesis.
I don’t think that the warm nose around 600mb was to blame for this. We still had robust deep convection form despite that warm nose. Perhaps that warm nose prevented discreet supercell formation ahead of the line, but it doesn’t explain the QLCS’ features itself. Only explanation I can really think of is the dryness of the atmosphere leading to downdrafts that were just too cold & stable to sustain tornadogenesis. I’m guessing we had many instances of failed tornadogenesis as a result of this. Studies have shown that QLCS tornado risk increases as PWAT increases, and these factors may be related. There are some notable exceptions, however.. Jan 12 of this year featured relatively low pwats and yet produced several sig tors.
Thoughts on this? We had mesocyclogenesis happen along the QLCS. We had decent separation at times between individual updraft regions. We had kinks, inflow notches, reflectivity drops.. only lacked, in general, successful tornadogenesis.