SPC MD 686

MD 0686 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEAST/COASTAL TEXAS Mesoscale Discussion 0686 NWS Storm Prediction Center Norman OK 0246 PM CDT Sat May 09 2026 Areas affected...portions of southeast/coastal Texas Concerning...Severe potential...Watch unlikely Valid 091946Z - 092145Z Probability of Watch Issuance...20 percent SUMMARY...A conditional risk for isolated large hail and damaging wind gusts exists across portions of southeast Texas this afternoon. DISCUSSION...Latest regional radar/satellite imagery depicts ongoing attempts at convective initiation along and south of a weak/remnant surface boundary across portions of southeast Texas, with an isolated thunderstorm noted near the Austin Metro. This activity is occurring immediately downstream of a mid-level shortwave trough, with cool temperatures aloft and a moist low-level air mass supporting moderate to locally strong buoyancy (2000-3000 J/kg MLCAPE per latest mesoanalysis and regional ACARS soundings). Enhanced southwesterly flow aloft ahead of this feature (as sampled by the POE/LCH VAD profiles) is contributing to 40-50+ kts of effective bulk shear, supportive of supercells; however, this greater shear is largely displaced towards the eastern portions of the discussion area (well ahead of the shortwave trough axis) with much weaker shear farther west. Should a thunderstorm develop/persist within the more favorable environment farther east, the resultant elongated hodographs coupled with modestly steep mid-level lapse rates will support an attendant risk for large hail. Infiltrating dry mid-level air (evident on latest GOES water vapor imagery) will also support greater evaporative cooling potential with stronger downdrafts (DCAPE of 900-1100 J/kg per latest mesoanalysis). The close proximity of the mid-level shortwave and its eastward progression along with the potentially unfavorable spatial overlap of better deep-layer shear and low-level convergence will likely yield a very narrow window for severe potential, with veering winds aloft and subsidence behind the shortwave tempering development/severe risk. Thus, while the ambient environment remains conditionally favorable for large hail/damaging winds across portions of far southeastern Texas, watch issuance appears unlikely at this time owing to uncertainty regarding the development/persistence of sustained storms within this better environment. Trends will continue to be monitored, however. ..Chalmers/Gleason.. 05/09/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LCH...SHV...HGX...FWD...EWX... LAT...LON 30509369 30189367 29849375 29639394 29459442 29449481 29449534 29539613 29649677 29899720 30189764 30409774 30589760 30709731 30919656 31009614 31079577 31139546 31129495 31009426 30769383 30509369 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more