Storm Prediction Center ..SUMMARY... Widespread severe wind gusts are forecast from the Ozark region to the lower Ohio Valley today. Additionally, very large to giant hail and tornadoes will be possible from the Red River Valley northeastward to the Ozark Plateau. Damaging winds, large hail, and a couple tornadoes will also be possible across the Tennessee Valley, middle Ohio Valley, and portions of the Mid-Atlantic.
Very steep midlevel lapse rates will overlie a richly moist and strongly heated boundary layer containing upper 60s to mid 70s F surface dew points and 15-18 g/kg mean mixing ratios. This yields MLCAPE locally exceeding 6000 J/kg in forecast soundings southeast of the cold front and outflows, and east of the dryline, from the western Ozarks across eastern OK to the Red River, amidst effective-shear magnitudes of 45-55 kt. Such extreme instability is near record levels, based on historic soundings. The CAPE-shear parameter space appears comparable to a fast-developing, dryline-initiated supercell/tornado event on 26 May 1997 in eastern OK, but with the added risk this time of a derecho on the northeast side. Such extreme instability will support explosive growth of thunderstorms that do break the cap -- whether through forced ascent on a cold pool or front, or in any discrete to semi-discrete cells that can move off the dryline. Dryline-storm risk is conditional and more isolated due to the strong EML and related CINH, but also potentially dangerous with giant hail of 3-5 inches in diameter and significant tornadoes possible. By late evening, a swath of convection should extend from the Ohio Valley into southern OK and perhaps north TX, with the overall severe threat diminishing overnight. more here
Severe Weather *Click pics to make larger and for loops.. SPC and GOES16