SPC AC 231010

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0410 AM CST Tue Nov 23 2021

   Valid 231300Z - 241200Z

   ...NO THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Severe thunderstorms are not expected.

   ...Synopsis/Discussion...
   A progressive, well-amplified synoptic pattern will continue over
   the CONUS through the period, as one trough exits the East and
   another traverses the West.  Intervening ridging will shift eastward
   from the Plains States across the Ohio and Tennessee Valleys. 
   Within the western troughing, a strong northern-stream shortwave
   trough is moving inland over the Pacific Northwest, while an
   initially separate, slow-moving, southern-stream perturbation is
   evident in moisture-channel imagery off the southern CA and western
   Baja coastline.  These two features will become increasingly
   well-phased through the period as they move eastward toward the
   Rockies and over northwestern MX.  

   By 00Z, the southern-stream trough should reach from central AZ to
   central Baja.  Large-scale lift to its east, and weak but sufficient
   low/middle-level moisture, will support widely scattered rain and
   snow showers (elevation dependent) amidst small, shallow buoyancy
   over eastern AZ and the Four Corners region.  While a rogue
   lightning flash cannot be ruled out, forecast soundings reasonably
   suggest CAPE will be too shallow and weak for a general thunderstorm
   threat (coverage less than 10%).  Elsewhere, surface cold-frontal
   passage has rendered the air mass east of the Rockies too stable for
   thunderstorms.  Trailing Gulf return flow will be too incomplete for
   enough buoyancy to support thunderstorms until day 2.

   ..Edwards.. 11/23/2021

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z