SPC AC 070713

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0213 AM CDT Fri Aug 07 2020

   Valid 091200Z - 101200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

   ...SUMMARY...
   Strong to severe thunderstorms are expected across parts of the
   northern Plains and Upper Mississippi Valley Sunday afternoon and
   evening. Large hail and wind damage should be the primary threats.

   ...Northern Plains/Upper Mississippi Valley...
   An upper-level trough is forecast to move eastward across the
   northern High Plains on Sunday as a 60 to 80 kt mid-level jet moves
   through the base of the trough. At the surface, a fast-moving cold
   front will advance eastward across the northern Plains. The front is
   expected to reach the eastern Dakotas by afternoon. Ahead of the
   front, surface dewpoints in the upper 60s and lower 70s F will
   contribute to strong destabilization. Thunderstorms are forecast to
   develop along the front in eastern North Dakota during the mid
   afternoon and move eastward across northern and central Minnesota
   during the late afternoon and early evening. Thunderstorms could
   develop southwestward into west-central Minnesota and far
   northeastern South Dakota. Additional thunderstorms will be possible
   eastward across the warm sector into the western Great Lakes region.

   Ahead of the front, model forecasts suggest that MLCAPE could reach
   the 3000 to 4000 J/kg range in parts of the Upper Mississippi Valley
   by late afternoon. Forecast soundings across north-central Minnesota
   at 21Z show supercell wind profiles with 15 kt surface winds veering
   to the west-southwest at 50 kt in the mid-levels. This should be
   favorable for severe storms along the front. Supercells will be
   capable for producing large hail and damaging wind gusts. The
   potential for damaging wind gusts could increase as a line of storms
   organizes along the front during the early to mid evening. At this
   point, the main uncertainty with the forecast is the timing of the
   cold front. A slower or faster frontal speed could result in the
   slight risk being displaced either eastward or westward. The slight
   risk is currently focused on the area where model forecasts are in
   best agreement concerning the positions of the front and instability
   axis near and after peak heating.

   ..Broyles.. 08/07/2020

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