SPC AC 300545

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1145 PM CST Mon Nov 29 2021

   Valid 021200Z - 031200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   A couple of weak thunderstorms are possible near the Rio Grande
   River and higher terrain of southwest Texas, but the risk of
   thunderstorms appears negligible elsewhere across the U.S. Thursday
   through Thursday night.

   ...Discussion...
   Aside from some suppression due to a significant digging short wave
   impulse to the lee of the Canadian Rockies, strong mid/upper flow is
   forecast to persist in a broadly anticyclonic belt across the
   eastern mid-latitude Pacific through the northern U.S. Great Plains
   and Mississippi Valley, into the Mid Atlantic Coast vicinity by late
   Thursday night.  The leading edge of this jet is forecast to dig 
   southeast of the Mid Atlantic coast, to the south of a strengthening
   mid-level perturbation, which may support substantive further
   deepening of a surface cyclone across southern Quebec through the
   lower St. Lawrence Valley.  At the same time, a developing
   perturbation emerging from persistent weak mid/upper troughing in
   the subtropical westerlies is forecast to overspread parts of the
   southern Rockies, Rio Grande River and higher terrain of southwest
   Texas, and adjacent southern Great Plains.  As this occurs, surface
   ridging initially encompassing much of the Gulf Coast and Gulf of
   Mexico may begin to slowly weaken.  However, low-level moisture
   return likely will remain generally modest, and confined to the
   lower Rio Grande Valley into portions of south central Texas through
   this period.

   Lower/mid-level moisture return emanating from the subtropical
   eastern Pacific likely will accompany the upper impulse, across the
   Rio Grande Valley into parts of the southern Great Plains.  In the
   presence of modestly steep lapse rates across the higher terrain of
   southwest Texas, it is possible that this may contribute to
   sufficient instability to support a couple of thunderstorms late
   Thursday afternoon.  Weak destabilization rooted in mid-levels
   (roughly around 700 mb) is possible farther northeastward, across
   parts of the Texas South Plains and Edwards Plateau into central
   Texas by late Thursday night.  However, it is not yet clear that
   this will support a risk of convection capable of producing more
   than occasional, very isolated lightning flashes.

   ..Kerr.. 11/30/2021

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z