SPC AC 030730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Fri Aug 03 2018

   Valid 051200Z - 061200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   HIGH PLAINS TO THE UPPER GREAT LAKES...

   ...SUMMARY...
   Strong/locally severe storms will be possible Sunday from the
   central High Plains region east-northeast to the Upper Great Lakes.

   ...Synopsis...
   Large-scale ridging aloft will persist over the southern half to
   two-thirds of the U.S. Sunday.  The most pertinent feature with
   respect to deep moist convection appears likely to be a short-wave
   trough crossing the northern Plains, which should gradually become
   absorbed within the southern fringe of a broader cyclonic flow field
   surrounding a central Canada upper trough.

   At the surface, a southwest-to-northeast baroclinic zone is forecast
   to extend from the central High Plains northeast to the upper Great
   Lakes, is expected to sharpen a bit with time, as it drifts very
   gradually southward.  A second/weak front may follow, shifting south
   across the Canadian Prairies toward/across the International Border
   with time.  Elsewhere, high pressure should largely prevail over the
   eastern states, with a weak/nondescript pattern over much of the
   West.

   ...Central High Plains east-northeast to the Upper Great Lakes...
   Scattered thunderstorms will likely be ongoing over portions of the
   north-central U.S. early in the day, near a weak/southward-drifting
   cool front.  Though the free warm sector south of the front should
   remain capped, destabilization near the boundary -- and possibly in
   the post-frontal upslope airmass evolving over the central High
   Plains -- is expected, which should fuel an afternoon increase in
   storm coverage/intensity near the slowly advancing front.  

   With a belt of moderately strong flow west-southwesterly flow aloft
   expected to the cool side of the front, shear in the vicinity of the
   boundary should prove sufficient for a few of the developing storms
   to become severe.  Primary threats would be locally damaging winds
   and hail, though somewhat a somewhat anafrontal scenario may
   ultimately evolve, with storms developing either just north of the
   front or else becoming quickly undercut -- which would tend to limit
   severe risk.  As such, only a MRGL/5% will be introduced at this
   time.

   ..Goss.. 08/03/2018

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