SPC AC 280717

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0217 AM CDT Sun Jun 28 2020

   Valid 301200Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE DAKOTAS AND NEBRASKA...

   ...SUMMARY...
   A few severe storms will be possible across portions of the northern
   and central Plains on Tuesday.

   ...Synopsis...
   An upper low over the Northeast is progged to remain essentially
   stationary through the period, while gradual eastward progression of
   the western upper trough continues.  Despite an overall advance of
   this trough, a broad zone of cyclonic flow will remain over much of
   the West as disturbances continue digging southeastward along the
   back side of the trough.  Meanwhile, the eastward-advancing portion
   of this trough is progged to take on an increasingly negative tilt
   as it impinges on persistent central U.S. ridging.

   At the surface, a cold frontal advance across the northern High
   Plains into the Dakotas is expected, while farther south a low is
   forecast to linger over the Kansas vicinity.  Elsewhere, a generally
   weak/somewhat nondescript pattern will prevail.

   ...Portions of Colorado/Kansas northward across the Dakotas...
   Strong capping is forecast over the Dakotas and Nebraska during the
   day, given large-scale subsidence on the western fringe of a stout
   upper ridge.  As the surface cold front/trough advances, persistent
   capping may limit potential for development near and to the warm
   side of this boundary.  However, though any frontal convection may
   remain isolated, more widespread storm development appears likely in
   an elevated manner on the cool side of the boundary.  Storm
   development also may occur north of the Kansas surface low -- again
   most likely above a low-level inversion.  

   In any case, with steep lapse rates aloft resulting in substantial
   most-unstable CAPE, and moderately strong -- though meridional --
   flow through a deep layer, isolated severe storms are expected. 
   Along with risk for large hail, locally damaging winds will be
   possible with any storms developing within or near the warm sector. 
   Some severe potential will likely continue into the overnight hours
   as the upper trough continues to advance across the High Plains.

   ..Goss.. 06/28/2020

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