It would appear that we’re on the cusp of having our first severe weather watch of the night/event. The Storm Prediction Center indicates a severe thunderstorm watch may need to be issued in the coming hours for the eastern Permian Basin, Big Country, Concho Valley, and Edwards Plateau. Thunderstorm development is expected to increase after 12-1AM as upper-level lift arrives. Most storms will be ‘elevated’ above a more stable layer near the surface and north of a warm front. That’ll keep the threat of damaging winds and tornadoes very low. Hail, on the other hand, will be quite possible given instability aloft. Those storms will move northeast and could eventually be organized into line segments or clusters as they move toward western North Texas by 5-7AM. There is a conditional risk of surface-based storms later several hours from now in the Edwards Plateau and south of the warm front. If that development were to occur we’d have to watch for the potential for an isolated tornado. However, most storms tonight will be hailers.

03Z HRRR simulated weather radar from 1 AM to 8 AM this morning.

   Mesoscale Discussion 0311
   NWS Storm Prediction Center Norman OK
   1140 PM CDT Fri Apr 12 2019

   Areas affected...Southwest TX

   Concerning...Severe potential...Watch possible 

   Valid 130440Z - 130645Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Thunderstorm coverage is expected to increase across
   southwest TX over the next few hours. Some severe hail is possible
   with these storms.

   DISCUSSION...Strong moisture advection throughout the evening has
   significantly modified the low-level air mass across the region.
   Dewpoints across the area have increased 10 to 15 degrees over the
   last 3 hours with much of the region now characterized by dewpoints
   in the upper 40s and low 50s. At the same time, ascent attendant to
   the shortwave trough moving through northern Mexico continues to
   increase, resulting in both an increase in high-level cloudiness
   over the region and a deepening of the surface low centered near
   FST. Continued moisture advection amidst this ascent, surface
   convergence, and increasing instability is expected to result in
   eventual convective initiation. 

   Current expectation is for most of these storms to be elevated north
   of the warm front, although surface-based development cannot be
   entirely ruled out later tonight across portions of the Edwards
   Plateau. Vertical shear supports updraft rotation, with hail
   possible within the more persistent and robust updrafts.

   ..Mosier/Guyer.. 04/13/2019