Storm Prediction Center Mesoscale Discussion 858

   Mesoscale Discussion 0858
   NWS Storm Prediction Center Norman OK
   0158 PM CDT Sun May 18 2025

   Areas affected...Northwest to west-central Texas

   Concerning...Severe potential...Watch likely 

   Valid 181858Z - 182130Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorm development along the dryline is expected
   roughly between 20-22 UTC across northwest to west-central Texas.
   The convective environment will support supercells capable of large
   hail, severe gusts, and a few tornadoes. Watch issuance is likely as
   storms begin to develop.

   DISCUSSION...Recent GOES visible imagery shows shallow, but slowly
   deepening, cumulus along and just ahead of a sharpening dryline as
   it continues to mix east and boundary-layer depth increases amid
   filtered diurnal heating. Latest RAP/HRRR forecast soundings suggest
   any lingering MLCIN will be minimized as surface temperatures warm
   into the 92-95 F range over the next few hours within the warm
   sector. Regional VWPs show flow within the lowest 2-3 km AGL
   oriented roughly along the dryline, which should promote adequate
   residence times for parcels to reach their LFCs and initiate deep
   convection. Latest high-res solutions suggest this should occur
   generally between 20-22 UTC. Thunderstorms will mature within a very
   unstable air mass with MLCAPE values exceeding 4000 J/kg and
   effective shear on the order of 40-50 knots. Limited directional
   shear will initially promote splitting supercells with an attendant
   very large hail threat (most probable max hail size may be 2-3
   inches in diameter). Southeasterly low-level winds across northwest
   TX may support adequate low-level veering for some tornado threat.
   Further south (roughly south of I-20), 1.5 to 2.5 km LCL heights and
   more backed low-level flow will modulate the initial tornado
   potential. After 00 UTC a strengthening low-level jet will increase
   low-level hodograph curvature and support an increasing tornado
   threat with any remaining discrete right-moving supercells across
   much of central/northern TX. Watch issuance will likely be needed as
   thunderstorm initiation becomes more imminent.

   ..Moore/Hart.. 05/18/2025

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

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

   LAT...LON   30980132 31340102 32480013 32860000 33250004 33760012
               34079996 34279965 34239910 34149872 33989849 33609835
               33029840 32379865 31779894 31059956 30879979 30480066
               30370100 30450133 30660147 30980132 

   MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN