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Storm Prediction Center Mesoscale Discussion 2155

Published Date and Time: 2026-08-27 18:34:00



Mesoscale Discussion 2155
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   Mesoscale Discussion 2155
   NWS Storm Prediction Center Norman OK
   0533 PM CDT Thu Aug 27 2026

   Areas affected...portions of southern South Dakota and central
   Nebraska

   Concerning...Severe Thunderstorm Watch 633...

   Valid 272233Z - 272330Z

   The severe weather threat for Severe Thunderstorm Watch 633
   continues.

   SUMMARY...A cluster of supercells will remain capable of large to
   very large hail this evening. With time, upscale growth into a
   cluster could promote an increasing risk for severe wind gusts.

   DISCUSSION...As of 2230 UTC, regional radar imagery showed a cluster
   of well-developed supercells ongoing over far southern SD and
   north-central NE. 3000 J/kg of MLCAPE and 40-50 kt of northwesterly
   deep-layer shear should continue to promote supercell structures
   with strong updrafts. Steep mid-level lapse rates (8-9 C/km) and 500
   mb temps of -10 to -11C will support hail with these storms. Some
   hail could be 2+ inches in diameter, especially with the more
   discrete storms on the western end of the ongoing cluster.

   Numerous storm interactions with storm splits are being observed
   over Cherry County, NE and far southern SD. Continued clustering and
   upscale growth appear likely over the next couple of hours and is
   also supported by short term model guidance. Further upscale growth,
   the strongly buoyant environment and sufficient deep-layer shear may
   favor an increasing risk of damaging gusts. A few gusts of 75+ mph
   are possible over central and possibly southern NE later this
   evening if a sufficiently strong cold pool is able to become
   established.

   ..Lyons.. 08/27/2026

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...LBF...UNR...CYS...

   LAT...LON   43070341 43610083 42860025 42159987 41899986 41780026
               41570114 41520201 41580234 41810270 42050311 43070341 

   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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