SPC AC 161723

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1223 PM CDT Thu Sep 16 2021

   Valid 171200Z - 181200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Organized severe thunderstorms appear unlikely across the contiguous
   United States on Friday.

   ...Great Lakes through Midwest and central Plains...

   Scattered thunderstorms will be in progress 12Z Friday along a cold
   front and in association with a northern-stream shortwave trough
   from the upper Great Lakes into the upper Midwest regions. The front
   will continue east and southeast through the Great Lakes and central
   Plains during the day. Weak to modest instability is expected in the
   pre-frontal warm sector with near 500 J/kg MLCAPE over a portion of
   the Great Lakes to 1500 J/kg across KS into northern MO and southern
   IA, where a few strong storms with gusty winds and small hail will
   be possible during the afternoon. Weak vertical shear should limit
   the potential for an organized severe threat from KS to the Midwest.
   Farther northeast across the Great Lakes, vertical wind profiles
   accompanying a northern-stream shortwave trough will be more
   favorable for severe storms, but weak instability should remain a
   limiting factor.

   ...Southern Arizona...

   Gulf moisture will begin to return to a portion of southern Arizona
   contributing to 500-1000 J/kg MLCAPE by late afternoon. Diabatic
   warming will result in inverted-V profiles, and a few storms may
   develop in this regime by late afternoon or early evening. A couple
   of strong convective gusts cannot be ruled out, especially where
   instability will be locally higher across far southern and southwest
   AZ, but the overall threat appears too marginal to introduce severe
   probabilities at this time.

   ..Dial.. 09/16/2021

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z