SPC AC 200555

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Wed Sep 20 2023

   Valid 201200Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF
   EASTERN OKLAHOMA...WESTERN ARKANSAS AND FAR NORTHEAST TEXAS...

   ...SUMMARY...
   Thunderstorms, associated with hail and marginally severe winds,
   will be possible across parts of eastern Oklahoma, western Arkansas
   and far northeast Texas late this afternoon and evening.

   ...Eastern Oklahoma/Western Arkansas/Far Northeast Texas...
   A shortwave trough will move slowly eastward into the lower to mid
   Mississippi Valley today. At the surface, south-southeasterly flow
   will help maintain a moist airmass located from east Texas northward
   into eastern Oklahoma. Surface dewpoints will be in the mid to upper
   60 F along this corridor, with moderate instability developing by
   afternoon. As surface temperatures warm during the day, isolated to
   scattered convective initiation is expected across part of this
   airmass. The greatest convective coverage is expected from eastern
   Oklahoma into western Arkansas, where low-level flow is forecast to
   be maximized. RAP forecast soundings in eastern Oklahoma around
   00Z/Thu show moderate deep-layer shear with 700-500 mb lapse rates
   near 8 C/km. This will likely support an isolated severe threat with
   rotating storms possible. Hail and marginally severe gusts will be
   the primary threats. At this time, the stronger forcing with the
   shortwave trough and strongest instability appear to be dislocated
   from one another, with the shortwave trough well toward the east.
   This, combined with the potential for a very small maximized threat
   area, will drive the decision to maintain a marginal risk for this
   outlook cycle.

   ..Broyles/Bentley.. 09/20/2023

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