SPC AC 032000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Fri May 03 2024

   Valid 032000Z - 041200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN A PART OF
   WEST TX...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH NE TO
   THE SOUTH-CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Giant hail, a few tornadoes, and severe wind gusts are possible over
   parts of west to central Texas through this evening. Scattered
   severe wind and hail are also possible over parts of the central
   Great Plains, mainly this evening into tonight.

   ...20Z Update...
   Across parts of west to central TX, initial supercell development is
   underway along the I-20 corridor between MAF/ABI. Despite modest
   lower-level shear, the large buoyancy and favorable elongation of
   the mid to upper portion of the hodograph should foster a few
   intense supercells. While left-splits will move northeast,
   slow-moving right-movers should progress south-southeast towards the
   Concho Valley per recent WoFS and early afternoon CAM guidance.
   Giant hail will be the primary threat with some upscale clustering
   into the evening promoting potential for significant severe wind
   gusts as well. Given the relative early initiation this afternoon
   relative to the nocturnal increase in the low-level jet, have
   refrained from higher tornado probabilities, although a sub-10%
   strong tornado risk remains evident. 

   Across the south-central High Plains into southern NE, buoyancy
   recovery is well underway ahead of the lower-amplitude shortwave
   impulse cross the southern WY/northern CO portion of the Rockies.
   Primary change with this outlook is to increase the areal extent of
   the cat 2-SLGT risk somewhat to the east and south. This is driven
   by higher confidence in strong to isolated severe wind gusts
   accompanying multiple potential clusters and QLCSs evolving east
   from ongoing convection from the NE Panhandle to the Raton Mesa.

   ..Grams.. 05/03/2024

   .PREV DISCUSSION... /ISSUED 1137 AM CDT Fri May 03 2024/

   ...Southern Great Plains...
   Visible satellite imagery and morning surface analysis shows a very
   moist airmass across the Edwards Plateau northward to a residual
   effective boundary draped northwest to southeast across the TX South
   Plains into central TX.  Near and south of the boundary, low-level
   moisture approaching the daily climatological maximum for several
   raob sites (reference 12z DRT, BRO, CRP) will contribute to a large
   moisture reservoir across west TX by mid-late afternoon.  A
   north-south dryline intersecting the differential heating
   zone/residual boundary will help focus thunderstorm development
   later this afternoon/evening.  Insolation through peak heating will
   contribute to very large to extreme buoyancy (3000-4000+ J/kg
   MLCAPE) across the Enhanced Risk area.  The nose of a westerly
   250-mb speed max (70-90 kt) will move into west TX later this
   afternoon/evening acting to elongate hodographs.  Expecting heating
   and weak convergence in the vicinity of the aforementioned surface
   boundaries to contribute to a weakened cap by mid afternoon.  Widely
   scattered to scattered storms are expected to develop through the
   early evening according to the latest model guidance.  Large to
   giant hail (max size 3-4+ inches in diameter), a few tornadoes, and
   severe gusts are possible across the TX South Plains extending
   southeastward into portions of the Big Country.  Depending on
   storm-scale interactions and local augmentation of the low-level
   wind profile, a strong tornado cannot be ruled out, but uncertainty
   at these scales precludes a delineated risk area.  Some upscale
   growth into a severe cluster is expected across west-central TX this
   evening with severe gusts perhaps becoming the primary hazard late.

   ...Central Plains...
   No change in forecast thinking for a large hail/severe gust risk
   area across the central Plains.  Though nowhere nearly as moist as
   the TX outlook area, a diurnally destabilized plume of moist
   advection should support a secondary relative max in severe
   potential along/ahead of the cold front and dryline from parts of
   eastern CO to western/northern KS and southern NE.  Convection
   should develop by mid/late afternoon in a regional convergence
   maximum near and northeast of the surface low, with MLCINH weakened
   by favorable diurnal heating.  Surface dewpoints in the 40s to low
   50s F should be common, with steep surface-500-mb lapse rates,
   500-1000 J/kg MLCAPE and well-mixed subcloud layers. 
   Effective-shear magnitudes around 40-50 kt indicate potential for
   organized convection -- both in quasi-linear form near the front and
   initially discrete (but later merging upscale) off the dryline. 
   Though activity will encounter a more-stable boundary layer with
   time and eastward extent across KS/NE, at least marginal severe-gust
   potential may last overnight as far eastward as parts of the
   Missouri Valley region.

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