SPC AC 112003

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0303 PM CDT Sat Apr 11 2020

   Valid 112000Z - 121200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHWEST
   OKLAHOMA INTO WESTERN AND CENTRAL TEXAS...

   ...SUMMARY...
   Severe thunderstorms are expected across parts of the southern Great
   Plains, with the greatest threat during the late afternoon through
   early morning from southwest Oklahoma into western and central
   Texas. Very large hail, tornadoes, and scattered damaging winds will
   be the primary hazards.

   ...Discussion...

   Only minor adjustments to previous forecast have been made for this
   update. Thunderstorms developing from northwest TX into southern OK
   this afternoon will continue to pose a risk for a few tornadoes,
   large hail and damaging wind.

   Later tonight additional storms will likely develop from southwest
   and western TX in association with an ejecting lead shortwave trough
   and as an accompanying Pacific front merges with the dryline. These
   storms will rapidly become severe as they move northeast and
   intercept richer low-level moisture. The shear/instability parameter
   space will favor for all severe hazards.

   ..Dial.. 04/11/2020

   .PREV DISCUSSION... /ISSUED 1124 AM CDT Sat Apr 11 2020/

   ...Synopsis...
   A closed mid-level low along the AZ/Sonora border will evolve into
   an open wave as it reaches the TX Trans-Pecos and northeast
   Chihuahua by early morning, in response to an upstream trough
   digging southeast into the northern Rockies. At the surface, a lee
   cyclone is expected to consolidate near the KS/CO border this
   afternoon/evening. The lee cyclone will induce strengthening
   southerly low-level flow and northward moisture transport across the
   southern Great Plains, as the remnant front near the TX coast
   advances north through tonight.

   ...North TX/southern OK to the Ark-La-Miss...
   Elevated convection is ongoing across parts of north-central TX, in
   a zone of low-level warm advection with increasing low-level
   moisture from the west and southwest. This activity will have the
   potential to produce isolated severe hail along the eastern edge of
   the expanding buoyancy plume, as it continues east through the rest
   of the period, eventually reaching the Ark-La-Miss region.

   Farther west, pockets of greater boundary-layer heating within the
   plume of upper 50s to mid 60s surface dew points will support a
   broad swath of moderate buoyancy with MLCAPE reaching 1500-2500
   J/kg. At least a few supercells are expected to develop across
   northwest TX and spread into southwest OK and western North TX this
   evening. The greatest coverage of severe should be from large hail,
   but a couple tornadic supercells and isolated severe wind gusts will
   be possible as well.

   ...Southern Edwards Plateau to central/east-central TX...
   Severe storm development is expected across the southern Edwards
   Plateau between 03-06Z as increasing height falls/forcing for ascent
   encounter the strong buoyancy along the west edge of rather rich
   low-level moisture. A couple intense supercells are expected roughly
   from the Del Rio to San Antonio vicinity where all significant
   severe hazards are possible. Upscale growth into a broader cluster
   is likely into east-central TX through early morning. Very large
   hail, a few tornadoes, and a swath of damaging winds will all be
   possible from late evening through daybreak.

   ...Interior south FL...
   A few thunderstorms are possible this afternoon as sea breeze
   circulations interact with the remnant front. Isolated large hail
   and damaging gusts may occur in an environment with MLCAPE of
   1000-1500 J/kg and effective bulk shear near 50 kt.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z