SPC AC 031729

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1229 PM CDT Fri May 03 2024

   Valid 041200Z - 051200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE PERMIAN
   BASIN OF WEST TX...

   ...SUMMARY...
   Scattered severe thunderstorms are expected across parts of west
   Texas from late afternoon through the evening on Saturday. Several
   storms may produce very large to giant hail, and a couple strong
   tornadoes are possible.

   ...Synopsis...
   A shortwave trough over the Upper Midwest will progress largely into
   northern Ontario, while a deep closed mid/upper low moves inland of
   the West Coast and reaches the CA/NV/OR border vicinity by early
   Sunday. A near 100-kt southern-stream upper jet will shift east from
   Baja/Gulf of CA across parts of northwest and north-central Mexico. 

   At the surface, a weak cyclone over the Upper MS Valley will move
   northeast. A trailing cold front will arc southwestward and push
   southeastward, likely from the Ozark Plateau to west TX by Saturday
   afternoon. This boundary should stall for a time in the Permian
   Basin/South Plains vicinity before being reinforced by convective
   outflows Saturday evening. 

   ...West TX vicinity...
   A weak, lee surface cyclone will diurnally deepen in the Trans-Pecos
   vicinity, within the left-exit region of the aforementioned upper
   jet impinging eastward. As the cold front settles south and stalls
   in vicinity of this low, a very rich western Gulf airmass to its
   south will become strongly unstable with MLCAPE of 3000-3500 J/kg
   expected by late afternoon. Convective initiation appears likely
   north of the cold front in southeast NM to the South Plains and
   farther south in the lee of the higher terrain of the Trans-Pecos.
   Several, largely elevated, supercells should become established
   north of the surface front. An elongated and nearly straight-line
   hodograph within the buoyancy profile should foster splitting cells
   with a threat for very large hail. Farther south, a few supercells
   along and south of the front across parts of the Permian Basin will
   also pose a threat for potentially giant hail as well while
   low-level shear is initially modest. But shear will strengthen into
   early evening, posing an increasing threat for a strong tornado or
   two. 12Z HREF members are nearly unanimous in suggesting very high
   updraft helicity values in at least one simulated warm-sector
   supercell during this time frame. 

   Deeper into the evening, convection should increasingly consolidate
   and become more widespread as low-level jet mass response continues.
   This should favor a mix of severe wind gusts with embedded large
   hail and tornado threats. These hazards will subside overnight, but
   should linger on an isolated basis towards parts of central TX.

   ...Mid-MS Valley to the Ozarks/Ark-La-Tex...
   A line of strong thunderstorms should be ongoing at 12Z Saturday,
   just ahead of the aforementioned cold front, from northwest MO into
   southeast KS. This activity should largely wane through the morning,
   but locally damaging winds and marginal hail will be possible until
   it decays. 

   Renewed thunderstorm development is expected during the afternoon,
   especially late along parts of the cold front where adequate
   boundary-layer destabilization occurs in the wake of the morning
   activity. With the Upper Midwest shortwave trough progressing
   northeast, strong mid-level southwesterlies will be displaced north
   of the destabilizing warm sector. Deep-layer shear will be modest,
   largely from 20-30 kts. This would be adequate for some small,
   multicell clusters. Overall severe threat will probably remain
   isolated and marginal with a mix of damaging winds and hail, largely
   peaking in the late afternoon to early evening.

   ..Grams.. 05/03/2024

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