Severe thunderstorm watch has been issued across the entire southern half of Oklahoma including OKC, as it appears likely supercells will initiate shortly across western OK and move SE along moisture nose and differential heating boundaries. TVN storm chasers are watching a WNW to ESE line of “towering cumulus” from Clinton to Vici through north of Lawton to south of Norman, including a few towers in the McAlester area.
The most favorable environment for updraft rotation and massive hail-producing supercells resides over the southwest quarter of Oklahoma as per latest RAP analysis, and the short-term forecast shows this environment holding steady state through evening. With easterly surface flow and SSE storm motions with right movers, effective helicities are already in excess of 150 m2/s2 south of I40 and west of I35. If a storm develops to the northwest of this region, it likely will quickly become supercellular and produce hail possibly larger than baseballs - depending on how strong any mesocyclones can persist. Here is the latest RAP analyzed effective helicity field:
It also looks like most of the capping inversion has eroded across most of southern OK, with subtle upper-level impulse approaching from TX Panhandle looking like the needed trigger mechanism for rapid supercell initiation over the next hour or two across W OK.
Another target is due south of OKC and north of Ardmore, as it seems the cap has eroded from E to W throughout the day, but it seems that low-level wind fields are little “messy” farther east. What are your thoughts?
Active few days ahead with N KS/S NE target interesting tomorrow, but will reserve posts on tomorrow for the appropriate thread. About to go live from the Dominator at http://tvnweather.com/live