SPC AC 230606

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0106 AM CDT Tue Mar 23 2021

   Valid 241200Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE LOWER MISSISSIPPI VALLEY...

   ...SUMMARY...
   Isolated severe thunderstorms are possible over a portion of the
   lower Mississippi Valley as well as the southern Plains mainly
   Wednesday evening into the overnight.

   ...Synopsis...

   A leading shortwave trough will lift northeast through the upper MS
   Valley and Great Lakes region Wednesday. Farther upstream, a
   low-amplitude impulse will move through the southern High Plains
   during the afternoon in advance of the primary high-amplitude
   shortwave trough that will move through northern Mexico before
   reaching the Rio Grande by the end of this period. Primary surface
   low will accompany the leading impulse into the Great Lakes during
   the day. The trailing front will front stall across southern TX but
   will retreat northwestward into northeast TX by early evening. A
   convectively reinforced boundary will also exist near the Gulf coast
   by 12Z Wednesday, and this boundary should weaken an lift slowly
   northward as a warm front during the period.

   ...Lower Mississippi Valley region...

   Thunderstorms may be ongoing along the Gulf Coast region from
   southern LA into southern MS and AL. This activity may pose a
   marginal severe threat early in the period. Mid-level temperatures
   will warm during the day due to advection of warmer air aloft within
   the southwesterly flow regime. While destabilization will occur in
   vicinity of this boundary, a mid-level capping inversion and weak
   forcing might inhibit robust surface-based thunderstorm development
   during most of the day. The low-level jet will strengthen during the
   evening in this region resulting in an increase in destabilization
   and isentropic lift farther north into LA, MS, AR and western TN.
   Thunderstorms will likely develop in this region during the evening
   and overnight. Current indication is that these storms will remain
   at least slightly elevated with 1500-2000 J/kg MUCAPE and 45+ kt
   effective bulk shear supporting a risk for mainly large hail. A
   tornado cannot be ruled out given strength of low-level shear, but
   will be conditional upon surface-based storm development.

   ...Southern Plains...

   Richer low-level moisture will return northwestward through TX as
   the boundary retreats northwestward. At least modest instability is
   expected by early evening across portions of central through north
   central TX with marginal CAPE farther north into OK where moisture
   will be more limited beneath cold temperatures aloft. A secondary
   frontal push will occur in wake of shortwave trough lifting
   northeast through OK. This may contribute to the development of
   isolated storms across TX during the evening where strong deep shear
   will support a threat for locally strong wind gusts and hail. A few
   storms may also occur in OK in association with the shortwave
   trough, and this activity may also produce a few instances of hail
   and locally strong wind gusts during the evening.

   ..Dial.. 03/23/2021

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z