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Storm Prediction Center Mesoscale Discussion 316

   Mesoscale Discussion 0316
   NWS Storm Prediction Center Norman OK
   0303 PM CDT Tue Apr 06 2021

   Areas affected...Parts of south central Nebraska into western
   portions of central Kansas

   Concerning...Severe potential...Watch possible 

   Valid 062003Z - 062200Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Scattered vigorous thunderstorm development is possible
   across the region by 5-6 PM CDT, with large hail expected to be the
   primary potential severe hazard into early evening.

   DISCUSSION...Seasonably strong boundary-layer heating/mixing is
   ongoing, within a narrow pre-cold frontal corridor wrapping into the
   vicinity of a modest surface cyclone centered west/northwest of Hill
   City, KS.  To the east of this axis, weak to modest low-level
   moisture return on southerly low-level flow continues.  Beneath
   rather steep mid-level lapse rates associated with warm and capping
   elevated mixed-layer air, it appears that this is contributing to
   mixed-layer CAPE up to around 1500 J/kg, east of Dodge City through
   Russell, KS, into the vicinity of Lexington, NE.

   Meanwhile, just to the west, it appears that at least weak mid-level
   cooling is underway in response to the east-northeast progression of
   an initial impulse within larger-scale mid-level troughing
   progressing across and east of the Rockies.  As this begins to
   overspread the vicinity of the ongoing axis of boundary-layer
   destabilization, mid-level inhibition is expected to weaken
   sufficiently to contribute to the initiation of scattered vigorous
   thunderstorm activity within the next few hours. The past several
   runs of the Rapid Refresh and High Resolution Rapid Refresh have
   been suggestive that this may occur as early as 22-23Z.

   Although stronger southerly low-level flow, including 30-40+ kt
   around 850 mb, appears offset to the east of the instability axis,
   deeper-layer shear beneath 40 kt flow near the 500 mb level may
   contribute to sufficient shear for the evolution of supercell
   structures capable of producing large hail.  Locally strong to
   severe surface gusts may also be possible, but a more general
   increase in risk for severe wind gusts probably will await
   interaction of upscale growing convection with a strengthening
   low-level jet later this evening.

   ..Kerr/Hart.. 04/06/2021

   ...Please see for graphic product...


   LAT...LON   40870005 41179909 40719828 39149809 37969829 37609891
               37629962 38789964 40069970 40870005