Well... Today's chase didn't get as planned. Despite RUC forecasts of initiation along the OK / TX panhandle border, the forcing/convergence proved too weak to develop convection. Wind shear was strong in that area, and CAPE was likely 800-1500 j/kg. However, none of that mattered as we sat in Hollis, OK, (extreme sw OK) under mostly sunny skies and watched the Cu dissipate. Oh well, I knew it was a big gamble, so it's not a huge disappointment. I'm still frustrated that I haven't been able to get Kim on a successful chase. She's chased with me a dozen or so times, and the vast majority of those have been busts (clear-sky or otherwise). I'm
really hoping that I can get her on a successful chase sometime soon.
The 0z NAM from this evening makes tomorrow look very appetizing! A very strong upper-level trough will eject out of the southwestern US tonight and tomorrow, leading to strong cyclogenesis in eastern Nebraska. The dryline will set up along the I35 by early afternoon, before marching eastward as a very intense vort max slams into central and eastern KS. Forcing from this feature (i.e. DPVA) will be weaker south of I40 in eastern OK (and northern TX). Shear profiles will be more than sufficient for supercells, and low-level shear (
if the winds remained backed as the 0z NAM indicates) will be sufficient for strong tornadoes. The deeplayer shear vectors (which are progged to be >50kts east of the dryline) will be more normal to the dryline south of I40. I'm not sure that we'll see 65-68F Tds near the Red River as the NAM suggests, but we won't know that until morning. Almost all models overforecasted surface Tds
and kept surface flow too backed on 3/12, so I'm a little hesitant to accept this solution.
Currently, I'm favoring the area south of I40 and east of I35 in OK and northcentral/northeastern TX. Shear vector orientation relative to the dryline will be nearly normal here, which should favor discrete activity. Strong shear, as indicated above, will be more than sufficient for intense supercells, and mid-60 Tds (*crossing fingers*) should help boost CAPE to ~2000 j/kg. I'm afraid we'll see rapid squall line development north of Tulsa as intense mid-level UVVs push over the dryline in a strong DPVA regime ahead of the vort max. Farther south, the vort max trails west a bit and is a little weaker, so DPVA should also be a little weaker. NAM does show very strong UVVs along the dryline at 850mb by evening, so we may see squall line development farther south as well. However, I'll take my chances given the shear vector orientation relative to the dryline. In addition, NAM is forecasting Bunkers storm motions of 35-45kts south of I40, with 50-55kts north of I40 into eastern KS.
In the end, I think a lot of what happens tomorrow will depend upon what the surface winds do. If the winds can remained back, moisture will likely not mix out as much (i.e. Tds will remain elevated), and shear profiles will remain in the very strong category. In addition, backed flow in the warm sector will also help provide convergence on the dryline, which may be necessary for this southern target, which is more removed from the intense mid-level forcing that'll occur farther north. On the other hands, if winds veer a bit (such as what happened on 3/12), Tds will mix out a bit, low-level shear will weaken, and we could end up with a faster transition to squall line.
Tornado Central
