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.
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