SPC AC 291240

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0740 AM CDT Sat May 29 2021

   Valid 291300Z - 301200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTH-CENTRAL HIGH
   PLAINS...

   ...SUMMARY...
   Scattered large hail, brief tornadoes, and isolated severe wind
   gusts are possible after about 2 PM MDT across the south-central
   High Plains.

   ...Central/Southern High Plains...
   Slowly intensifying storm development is expected during the early
   to mid-afternoon focused on the Palmer Divide vicinity along a
   surface trough, the Raton Mesa vicinity near a diurnally deepening
   surface cyclone, and in a upslope flow regime to the Sacramento
   Mountains. Low-amplitude upper-level ridging and modest-strength
   westerlies suggest both storm movement and updraft organization
   should be initially subdued. But the presence of moderate buoyancy
   with MLCAPE reaching 1500-2000 J/kg by late afternoon amid steep
   mid-level lapse rates will support a risk for a few supercells with
   a primary threat of large hail. Brief hybrid landspout-supercell
   tornadoes are possible along the surface trough and with any
   slow-moving supercell in southeast CO. 

   Longer-duration supercells should be maintained in the Raton Mesa
   vicinity aided by strengthening of the low-level jet this evening.
   This renders concern for a continued brief tornado risk in this
   region through about 02Z. Otherwise, slow-moving clusters with
   regenerative upshear convection should persist through most of
   tonight, particularly focused in the Raton Mesa vicinity. While an
   isolated severe wind threat is apparent, a greater risk for severe
   wind gusts should be curtailed by substantial MLCIN across much of
   western KS and the Panhandles. 

   ...Carolinas and far southeast VA...
   Afternoon thunderstorm development will be focused along a
   convergent southward-moving surface cold front. Despite weak
   mid-level lapse rates, pockets of stronger boundary-layer heating
   should boost MLCAPE to around 1000 J/kg MLCAPE. While a transient
   supercell may develop immediately along the portion of the frontal
   zone near the southeast VA/northeast NC border, multicells capable
   of isolated wind damage should be the most common mode/threat
   through early evening.

   ...Deep South TX...
   A decaying MCS should spread across the rest of Deep South TX
   through midday, and will likely continue to weaken overall.
   Nevertheless, steep mid-level lapse rates and abundant buoyancy
   sampled in the 12Z Brownsville sounding suggest a brief flare-up of
   isolated severe hail and wind is still possible until the MCS fully
   decays.

   ...Southeast TX...
   On the backside of a drifting MCV near the mouth of the Sabine
   River, scattered afternoon thunderstorms are possible along a weakly
   convergent surface boundary. Modest deep-layer shear within a
   west-northwest flow regime may be adequate for a few cells producing
   small hail and locally gusty winds.

   ..Grams/Gleason.. 05/29/2021

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