SPC AC 221244

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0744 AM CDT Sun Sep 22 2019

   Valid 221300Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF OK
   TO IL THROUGH THIS EVENING...

   ...SUMMARY...
   Isolated damaging winds, and perhaps a tornado or two, will be
   possible through this evening from parts of Oklahoma to Illinois.

   ...OK to IL through this evening...
   A midlevel shortwave trough with embedded perturbations over the
   central/northern High Plains will progress eastward to the MS Valley
   and Great Lakes by tonight.  In advance of an embedded speed max
   over the central High Plains, an associated weak surface cyclone in
   KS this morning will develop northeastward along a front toward
   Lower MI by early tonight.  A narrow corridor of richer low-level
   moisture, ranging from upper 60s dewpoints into IL to lower 70s in
   OK, will be maintained immediately in advance of the weak low and
   cold front today.

   A somewhat complex scenario will evolve today with widespread
   ongoing rainfall and some embedded thunderstorms from OK to WI. 
   Outflow from overnight convection and differential heating today
   will maintain the effective boundary from northern IL into central
   MO.  An embedded MCV is moving northeastward over southeast KS this
   morning, and per local VWPs and model forecasts, a 50 kt low-level
   jet will develop northeastward today with the weak frontal wave and
   ejecting midlevel trough.  Though widespread rainfall will continue
   to limit lapse rates, the rich low-level moisture and pockets of
   surface heating in cloud breaks will support MLCAPE ranging from 500
   J/kg this afternoon in IL to 1500 J/kg in OK.  Enhanced low-midlevel
   flow/shear along the effective surface boundary, potentially
   augmented by the remnant MCV moving from KS to MO, may support some
   embedded rotating storms and/or small bowing segments.  The threat
   for isolated damaging winds and a tornado or two will begin the
   first half of the day from southeast KS into OK, and continue into
   late afternoon/evening into IL.

   ..Thompson/Leitman.. 09/22/2019

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