SPC AC 250718

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0218 AM CDT Sat Jul 25 2020

   Valid 271200Z - 281200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MONDAY AFTERNOON
   AND EVENING ACROSS PARTS OF THE LOWER GREAT LAKES INTO LOWER OHIO
   VALLEY...

   ...SUMMARY...
   Strong thunderstorms may impact parts of the lower Great Lakes into
   lower Ohio Valley Monday afternoon and evening, accompanied by at
   least some risk for potentially damaging wind gusts.

   ...Synopsis...
   Within the mid-latitude westerlies, a broad mid-level low appears
   likely to gradually evolve within large-scale troughing developing
   eastward across Ontario into western Quebec Monday through Monday
   night.  Contributing to this evolution, at least one fairly
   significant short wave impulse is forecast to dig within the base of
   the troughing, across Upper Midwest, before turning eastward and
   northeastward across the Great Lakes into western Quebec.  

   A cold front associated with the mid-level troughing, likely
   reinforced by outflow associated with considerable thunderstorm
   activity, is forecast to continue to advance southeastward and
   southward through the lower Great Lakes, Ohio and middle Mississippi
   Valleys, and into portions of the southern Great Plains.  This will
   probably mostly remain well south of the stronger westerlies,
   beneath cooling but still rather warm mid-levels, which seems likely
   to limit the risk for severe weather.

   ...Lower Great Lakes into lower Ohio Valley region...
   In association with the progressive short wave impulse, models do
   suggest that strengthening of lower/mid-tropospheric flow is at
   least possible along a corridor of pre-frontal destabilization
   across the lower Ohio Valley into the lower Great Lakes region by
   Monday afternoon.  This may include southwesterly to westerly flow
   in the 850-500 mb layer increasing to 30+ kt, in the presence of
   moderate CAPE on the order of 1500-3000 J/kg.  This environment may
   support upscale growing convection capable of producing potentially
   damaging surface gusts, aided by heavy precipitation loading, late
   Monday afternoon and evening.

   ..Kerr.. 07/25/2020

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