If storms can get going across SE Texas, a tornado threat will undoubtedly evolve. The SPC has an enhanced risk of tornadoes that runs from Houston to the west near San Antonio.
The bottom two graphics show the 0-1km storm-relative helicity — where values of over 100 are widespread on the bottom left. On the bottom right, you can see the expected location of storms on a percentage basis. Both of these are what have forecasters so concerned.
The caveats I’m seeing this morning are a lack of low-level instability onshore, and the possibility high-resolution models are right and we might be looking at a widespread/very crowded storm mode. In a limited instability environment, this tends to prevent any one updraft from taking over. Thus, those are the two things to watch and are the obvious ‘failure modes’ of today’s event.
The potential for several tornadoes, including the Houston metro area, is certainly there though. Expect the threat to ramp up by late morning and it will peak sometime in the early-mid afternoon. We’ll be keeping an eye on it.