SPC AC 260730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Mon Apr 26 2021

   Valid 281200Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   SOUTHERN PLAINS THROUGH THE MID MS VALLEY...

   ...SUMMARY...
   Isolated severe thunderstorms are possible from the southern Plains
   through the Middle Mississippi Valley on Wednesday.

   ...Synopsis and Discussion...
   Southern-stream upper trough is forecast to move eastward throughout
   the day, ending the period extended from southwest KS through
   northern Mexico and phased with a northern-stream upper trough. This
   evolution will allow strong southwesterly flow aloft to persist over
   northern Mexico and the southern Plains while also expanding
   northeastward through the Mid MS Valley and into the middle OH
   Valley.

   Surface pattern early Wednesday morning will feature a cold front
   extending from a low over southern Lower MI southwestward to another
   low over western KS early Wednesday morning. A dryline is forecast
   to extend from the western KS low southward into southwest TX. This
   cold front will move southeastward throughout the day while
   gradually overtaking the dryline from northwest to southeast. 

   A broad area of low severe potential will extend throughout the warm
   sector in the vicinity of the front from central OK into western IN.
   In this region, persistent warm-air advection will likely allow the
   thunderstorm cluster ongoing over OK Wednesday morning to progress
   northeastward throughout the day. Cloudiness associated with this
   cluster will limit destabilization but robust vertical shear could
   still result in a few stronger storms capable of hail.  

   Farther south (from southwest/south-central OK southward through the
   TX Hill County), afternoon storm development appears possible along
   the dryline/cold front as these boundaries move
   eastward/southeastward.  However, evolution of Tuesday night's
   thunderstorms will impact overall likelihood for development as well
   the most probable locations for initiation. Any residual outflow
   boundaries would also play an important role for afternoon storm
   development. Given that these mesoscale details are uncertain at
   this forecast range, only 5%/Marginal probabilities were introduced
   with this outlook. Higher probabilities may be needed in later
   outlooks as these details become more predictable.

   ..Mosier.. 04/26/2021

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z