Mesoscale Discussion 0373
   NWS Storm Prediction Center Norman OK
   0554 PM CDT Wed Apr 17 2019

   Areas affected...south-central OK into northern and central TX

   Concerning...Severe potential...Watch likely 

   Valid 172254Z - 180100Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Convection will likely develop in the next 1-2 hours and
   watch will likely be needed by 00z. A localized tornado threat may
   develop in the vicinity of the Red River from north Texas into
   south-central OK in the short term with additional severe convection
   expected later this evening into central TX.

   DISCUSSION...Latest visible satellite imagery shows an increasingly
   agitated cu field across the Red River Valley into north TX along a
   sharp dryline extending southward from a surface low near CDS, and
   to the south of a warm front oriented west to east across
   south-central OK. Latest water vapor imagery also shows some deeper
   updrafts beginning to develop in the vicinity of Jack, Montague,
   Cooke, Wise and Denton Counties in north Texas. Furthermore, the
   increase of midlevel clouds further southwest across the Trans-Pecos
   and Permia Basin regions of western TX indicate that stronger
   forcing is now beginning to shift eastward into the region. This
   should support convective initiation in the next couple of hours
   across the MCD area. 

   In the short term, should isolated cells develop in the vicinity of
   the triple point in the Red River Valley, supercells capable of very
   large hail, damaging winds and tornadoes will be possible. While low
   level flow isn't particularly strong across this region, the warm
   front will enhance low level SRH. Mean mixing ratios between 12-14
   g/kg also will be more than sufficient for tornado production.
   Additionally, midlevel lapse rates between 8-9 C/km as sampled by
   the 20z OUN RAOB and 0-6 km shear greater than 45 kt will favor very
   large hail.

   Eventually, as forcing for ascent increases and the surface cold
   front begins to catch up to the dryline, additional, vigorous
   convection is expected to develop southward into central Texas this
   evening. This convection may initially pose a threat for very large
   hail before growing upscale into bowing line segments and
   transitioning to a damaging wind threat.

   ..Leitman/Hart.. 04/17/2019

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...FWD...OUN...SJT...

   LAT...LON   33199867 34369823 34339755 33689672 32789677 31899724
               31209802 30939883 31079932 31969954 33199867