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Mesoscale Discussion 511
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   Mesoscale Discussion 0511
   NWS Storm Prediction Center Norman OK
   0838 PM CDT Mon May 03 2021

   Areas affected...Portions of northeast TX...far southeastern
   OK...extreme northwestern LA...much of AR...and far southern MO

   Concerning...Severe potential...Watch likely 

   Valid 040138Z - 040345Z

   Probability of Watch Issuance...95 percent

   SUMMARY...The severe threat will increase this evening as storms
   approach from the west. Damaging winds should become an increasing
   concern. Isolated large hail and a couple tornadoes may also occur.
   Watch issuance is very likely.

   DISCUSSION...The OOZ sounding from LZK showed a very unstable
   airmass is present across much of AR to the south of a front, with
   around 3800 J/kg of MLCAPE observed. Robust, severe storms ongoing
   across north-central TX and eastern OK are expected to move eastward
   this evening into parts of northeast TX, much of AR, and eventually
   far southern MO later this evening. With generally upper 60s to mid
   70s surface dewpoints and steep mid-level lapse rates in place
   across these areas, moderate to strong instability will likely
   persist through much of the evening and early overnight hours, even
   with the loss of daytime heating. Enhanced mid-level flow associated
   with a shortwave trough over the southern Plains will overspread
   this region, with around 35-45 kt of effective bulk shear supporting
   continued storm organization and intensity.

   An ongoing cluster of storms in eastern OK has recently produced a
   measured severe wind gust to 71 mph. Current expectations are for
   this cluster to continue growing upscale this evening as it moves
   into AR, with additional severe storms potentially developing from
   north-central into northeast TX. Both large hail and damaging wind
   gusts will be a concern given the large reservoir of buoyancy
   available. But, scattered to numerous severe/damaging winds will
   likely become the primary concern as the storm mode becomes
   increasingly linear across AR this evening. Given the steep lapse
   rates aloft, there may be some potential for significant severe wind
   gusts (75+ mph) if storms form into a bowing complex. Finally, even
   though low-level flow is not forecast to be very strong, a couple
   tornadoes also appear possible with any embedded circulations given
   around 100-150 ms/s2 of effective SRH forecast. With the overall
   severe threat expected to increase in the next couple of hours,
   watch issuance will be needed.

   ..Gleason/Thompson.. 05/04/2021

   ...Please see for graphic product...


   LAT...LON   32939518 34359493 34459440 35439435 36159450 36639325
               36879169 36879078 36749009 36518976 36068982 34949053
               34359109 33579225 32739413 32289497 32169540 32939518 

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