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Mesoscale Discussion 506
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MD 506 graphic

   Mesoscale Discussion 0506
   NWS Storm Prediction Center Norman OK
   0828 PM CDT Wed May 23 2018

   Areas affected...NE Panhandle....West-central
   NE...Southwest/South-central SD

   Concerning...Severe Thunderstorm Watch 117...

   Valid 240128Z - 240300Z

   The severe weather threat for Severe Thunderstorm Watch 117

   SUMMARY...Potential for damaging wind gusts and hail will persist
   across the remaining portions of Severe Thunderstorm Watch 117.
   Convective trends will be monitored closely to determine the need
   for a downstream watch.

   DISCUSSION...Ongoing supercell in Oglala Lakota county is strongest
   storm of day across the region thus far. Recent MRMS MESH suggests
   hail around 3 inches possible with this storm. Large hail will
   remain possible with this storm during the next hour or so before a
   transition to a more linear mode reduces the potential for very
   large hail. Recent reflectivity surge northeastward as well as the
   influence of the approaching line segment farther southwest and
   interaction with an outflow boundary suggest upscale growth is
   probable with this currently discrete storm.

   To the south/southeast of this storm (i.e. across west-central NE),
   convection has recently increased along a residual outflow boundary
   in Cherry and Grant counties while the supercell that recently moved
   through Garden county appears to have become more outflow dominant.
   All of these signs point toward eventual cool pool amalgamation and
   eventual upscale growth into a linear MCS. 

   However, the downstream airmass will soon experience nocturnal
   stabilization and there is some question as to whether or not the
   MCS will be strong/mature enough to produce damaging wind gusts in
   the resulting stable low-level environment. Even if damaging wind
   gusts are not realized, steep mid-level lapse rates, sampled well by
   regional 00Z soundings, and increasing low-level flow will remain
   supportive of severe hail. Convective trends will be monitored
   closely to determine the need for a downstream watch.

   ..Mosier.. 05/24/2018

   ...Please see for graphic product...


   LAT...LON   42240409 43560354 44540104 44329968 42689943 41380102
               41090296 42240409 

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