Storm Prediction Center Oct 13, 2021 0730 UTC Day 3 Severe Thunderstorm Outlook

   SPC AC 130724

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0224 AM CDT Wed Oct 13 2021

   Valid 151200Z - 161200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID
   MISSISSIPPI VALLEY NORTHEASTWARD TO THE LOWER GREAT LAKES...

   ...SUMMARY...
   Risk for isolated instances of severe weather may evolve within a
   zone of thunderstorms stretching from the Lower Great Lakes
   southwestward to the Mid Mississippi Friday afternoon and evening. 
   Locally damaging wind gusts would likely be the primary risk.

   ...Synopsis...
   An upper trough crossing the Great Plains region during the day
   Friday will eventually cross the Upper and Middle Mississippi
   Valley, reaching a position stretching from the Upper Great Lakes
   south-southwestward to the Mississippi Delta region Saturday
   morning.  Meanwhile, broad ridges will flank the trough, both west
   and east, as it progresses across the central CONUS.

   At the surface, a low initially over the Illinois vicinity is
   forecast to develop/shift northeastward, entering Canada and
   reaching the Ottawa River Valley overnight.  Trailing from the low,
   a sharpening cold front will advance quickly across the Mid
   Mississippi/Lower Missouri Valleys and southern Plains through the
   day, and then continue eastward to reach the west slopes of the
   Appalachians by the end of the period.  Meanwhile, high pressure
   will prevail across the western half of the country through the
   period.

   ...Lower Great Lakes region southwestward to the Mid Mississippi
   Valley...
   Showers and scattered thunderstorms are forecast to be ongoing at
   the start of the period, from the Lower Great Lakes region
   southwestward to eastern portions of Kansas/Oklahoma/Texas early in
   the period.  This ongoing precipitation and associated cloud cover
   -- continuing through the day -- will act to limit warm-sector
   destabilization.

   As such, the thermodynamic environment is expected to be a limiting
   factor with respect to widespread/robust afternoon and evening
   convection.  Therefore, degree of severe potential remains
   questionable despite favorably strong/increasing deep-layer wind
   field with time.  At this time, it appears that a gradual ramp-up in
   convective intensity near and ahead of the front will occur, with
   the greatest risk for local severe weather -- likely in the form of
   gusty/damaging winds -- to extend from the Mid Mississippi/Ohio
   Valleys into the Lower Great Lakes region, primarily during the
   afternoon and evening hours.  With coverage of risk in question,
   will introduce only 5%/MRGL risk at this time.

   ..Goss.. 10/13/2021

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