SPC AC 240534

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1234 AM CDT Wed Mar 24 2021

   Valid 241200Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHERN PLAINS AND ARKLATEX...

   ...SUMMARY...
   Severe thunderstorms with isolated large hail and wind damage will
   be possible over parts of the southern Plains into the Arklatex,
   mainly this evening into tonight.

   ...Southern Plains/Arklatex...
   An upper-level low will move eastward across the Desert Southwest
   today as a mid-level jet rounds the base of the trough. Ahead the
   system, moisture advection will take place across the southern
   Plains. A dryline is forecast to become better defined in the Texas
   Hill Country with this feature extending as far north as
   north-central Texas by early evening. To the east of the dryline,
   surface dewpoints in the lower to mid 60s F will contribute to the
   development of a pocket of moderate instability in the Texas Hill
   Country. Weak instability is forecast to extend northward across the
   Red River into southern OKlahoma.

   As the upper-level trough moves into the southern High Plains,
   large-scale ascent will first increase across southern Oklahoma and
   north Texas. Lift will be aided by the exit region of the mid-level
   jet. The lift combined with increasing low-level convergence should
   result in the development of a north-to-south band of convection to
   the west of the Dallas/Fort Worth Metroplex during the late
   afternoon and early evening. The southern part of the band is
   forecast to move across the Texas Hill Country. The models differ on
   how much instability will develop across the Texas Hill Country. The
   NAM suggests MLCAPE could increase to 2000 J/kg by early evening but
   the RAP and HRRR are considerably less. If the NAM verifies, then
   supercell development would be possible or even likely in the
   strongly sheared environment. Large hail and wind damage would be
   the primary threats as cells move from near the I-35 corridor at
   Waco east-northeastward across northeast Texas during the evening.

   Further north across north-central Texas into southern Oklahoma,
   instability is forecast to be less, but still sufficient for a
   severe threat. A cluster of storms is forecast to organize across
   north Texas and southern Oklahoma, moving into the Arklatex around
   midnight. The primary threat would be isolated large hail. This
   cluster of storms, along with cells further to the south, may
   continue to have a severe threat during the overnight period.

   ...Lower Mississippi Valley/Central Gulf Coast States...
   Southwest mid-level flow will be in place today across the lower
   Mississippi Valley and central Gulf Coast region. A strong
   upper-level system will move into the southern High Plains as
   low-level moisture advection occurs across much of the western and
   central  Gulf. In response to the approaching system, a low-level
   jet will strengthen across the lower Mississippi Valley. Convection
   is expected to develop near the nose of the low-level jet and move
   northward across parts of Louisiana and Mississippi during the
   evening. Although the convection will be elevated in nature,
   forecast soundings from New Orleans to Biloxi
   increase MUCAPE into the 1000 to 2000 J/kg range. This combined with
   effective shear of 70 to 80 kt will support an isolated threat of
   hail and strong wind gusts. But due to the elevated nature of the
   storms, any threat will remain marginal.

   ..Broyles.. 03/24/2021

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