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Mesoscale Discussion 668
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   Mesoscale Discussion 0668
   NWS Storm Prediction Center Norman OK
   1255 PM CDT Fri May 22 2020

   Areas affected...Portions of North-Central Texs

   Concerning...Severe potential...Watch likely 

   Valid 221755Z - 221930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorm initiation is expected within the hour
   somewhere near Young County, TX.

   DISCUSSION...Towering cumulus have persisted along the western
   portion of an outflow boundary from the morning MCS. This boundary
   currently extends from near Childress to the northern suburbs of
   Dallas/Fort Worth. Temperatures south of this boundary have warmed
   into the mid to upper 80s with dewpoints in the upper 60s to low 70s
   yielding MLCAPE around 3000 J/kg per SPC mesoanalysis. This boundary
   has slowed its southern motion recently and may start to lift back
   north slightly within the next hour or two as it encounters stronger
   southerly flow ahead of the boundary. 

   The combination of short residence time along the boundary and dry
   air entrainment have stunted storm development along the boundary
   thus far with evidence of a few orphaned anvils. However, SPC
   mesoanalysis indicates MLCIN has eroded near the boundary.
   Therefore, it shouldn't be long before storms start to develop. The
   most likely area for initial storm formation is in Young County, TX
   where convergence is maximized along the outflow boundary. This is
   further supported by the 17Z WoFS which shows a maturing storm in
   this area between 18Z and 19Z. The strong instability, combined with
   effective shear around 35-40 knots per SPC mesoanalysis supports
   some supercellular structures. Mid-level lapse rates around 8-9 C/km
   per 12Z FWD sounding will support the threat for very large hail
   with these storms, especially initially. 

   Stretching of low-level vorticity in the region of the outflow
   boundary may provide a brief tornado threat this afternoon, but
   weakening low-level flow (per FWS and FDR VWP) will be a limiting
   factor to the overall tornado threat this afternoon. However, later
   this evening, the low-level jet is expected to strengthen
   substantially which will enlarge hodographs and lead to an
   increasing tornado threat.

   ..Bentley/Hart.. 05/22/2020

   ...Please see for graphic product...


   LAT...LON   33570019 33949994 34139947 33759830 33319763 32659758
               32539908 32619996 33090048 33090048 33570019 

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