Wednesday/Thursday Deep South Severe Weather Threat (North Texas Focus)

NORTH TEXAS SIGNIFICANT SEVERE WEATHER POTENTIAL:

Severe storms will be an issue over the next 48 hours across North TX and much of the Deep South as a powerful upper level storm system moves east into a region with an expansive unseasonably warm and moist air mass. Wednesday will feature the "warm up" event with localized severe hail and Thursday appears to have a much more high end threat to it--including significant tornadoes for portions of North Texas.

WEDNESDAY (WARM UP EVENT): On Wednesday, isolated to widely scattered storms, potentially a few supercells will develop during the morning hours as Gulf moisture surges north meeting up with an advancing cold front. A jet streak moving in from Mexico and the cold front will serve as subtle forcing mechanisms to allow some isolated convection, but an increasing warm inversion through the day and decreasing forcing will keep the threat isolated. Still--those few storms that develop will be in a strongly sheared environment which will foster updraft/downdraft separation and plenty of CAPE, steep lapse rates will support strong updrafts supportive of large hail. Not concerned with a tornado risk tomorrow due to poor low level directional shear.

THURSDAY:

The main upper level storm system ejects from the Four-Corners region providing large scale forcing. More Gulf moisture surges in from the south into a developing and deepening surface low over the Big Country that will ride northeast toward the Red River during the day. Attached to the surface low will be a west-east oriented warm front and a dry line extending southwest. Expect a widespread region of 63-70 deg dew points and surface temps in the mid to upper 70s which will yield 1500-2500J/kg CAPE in the warm sector.

Thursday could feature some early morning to midday storms as subtle forcing mechanisms ahead of the main upper low trigger storm development. These morning storms will likely organize to the northwest of DFW and ride along the Red River through the midday and afternoon. Initially, storms may start elevated (meaning they will primarily carry a hail threat) but eventually become surface based as the atmosphere destabilizes through the day. The low level winds in this region would be much more backed and supportive of strongly rotating storms with potentially long-lasting mesocyclones. Hodograph shapes in this warm frontal zone, just to the east of the strengthening surface are much more curved, especially with 0-1km segments--meaning the low level winds will be INCREASING AND VEERING STRONGLY with height. Storms that form in this environment would have much larger low level inflow region better supportive of ingesting horizontal spin induced by the large scale wind shear, tilt/stretch into the vertical via updrafts and downdrafts. This in conjunction with low LCLs (cloud bases) would support a strong and potentially long lived tornado threat for locations just northeast of DFW along the Red River into the Ark-La-Tex region. This includes places like Sherman-Denison, Paris, Clarksville, Sulphur Springs, Greenville, Texarkana, Hugo (OK), Idabel (OK) just to name a few.

Additional storm development would occur from north to south by mid afternoon along the dry line and impact more of the DFW area. I expect these storms to start out semi-supercellular, but then become linear fairly quickly as shear vectors will likely favor some storm interactions along the initiating boundary. Very large hail and damaging winds would be the primary threat, but the tornado threat would likely be a bit more reduced (but not zero) from DFW and points south with weaker low level directional/speed shear leading to less favorable hodographs. Note, that if we see any mesoscale boundaries alter the low level wind flow to be more backed farther south, this could raise the tornado threat farther south as well.