SPC AC 040709

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0209 AM CDT Sat Jul 04 2020

   Valid 061200Z - 071200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   NORTHERN HIGH PLAINS EASTWARD ACROSS SOUTH DAKOTA INTO THE UPPER
   MIDWEST...

   ...SUMMARY...
   Isolated strong to severe thunderstorms are possible from the
   northern High Plains eastward across South Dakota into the Upper
   Midwest on Monday.

   ...Synopsis...
   Upper ridging is forecast to still be in place from the
   Southwest/northern Mexico northeastward into middle/lower MO Valley
   early Monday morning. Enhanced westerly/southwesterly flow is
   anticipated north of this upper ridge, from central CA through the
   Upper Midwest and into Ontario. A low-amplitude shortwave trough is
   expected to progress eastward/northeastward within this belt of
   stronger flow, likely reaching the northern High Plains by late
   Monday afternoon. Elsewhere, a weak upper low is expected to drift
   slowly eastward over the lower MS Valley while a convectively
   augmented vorticity maximum moves southward from the TX Panhandle
   towards the TX Hill Country. Farther west, a strong shortwave trough
   is expected to move into the Pacific Northwest Monday evening. 

   ...Northern High Plains eastward into the Upper Midwest...
   Surface feature most related to severe thunderstorm potential will
   be a cold front initially extending from northwestern Ontario
   southwestward into north-central NE and then back northwestward into
   central WY. Central and eastern portions of this front are expected
   to gradually progress southward/southeastward throughout the day
   while the western portion remains largely in place. Thunderstorms
   are anticipated along the progressive portion of the front as well
   as back west across northeast WY and southeast MT. Instability will
   be greatest from central SD eastward into the Upper Midwest while
   stronger vertical shear is anticipated farther west across western
   SD into northeast WY and southeast MT. Isolated strong to severe
   thunderstorms are possible throughout this entire region. A somewhat
   greater risk may exist across the northern High Plains where the
   stronger vertical shear is anticipated, but storm coverage is still
   a bit too uncertain to introduce a 15% area with this outlook.

   ..Mosier.. 07/04/2020

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z