SPC AC 300530

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1130 PM CST Mon Nov 29 2021

   Valid 011200Z - 021200Z

   ...NO THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   The risk for thunderstorms appears negligible across the U.S.
   Wednesday through Wednesday night.

   ...Discussion...
   Although one significant short wave trough accelerating inland
   across the British Columbia coast may suppress its amplitude, strong
   flow is forecast to persist in a broadly anticyclonic belt across
   the mid-latitude eastern Pacific through the northern U.S. Great
   Plains and upper Mississippi Valley during this period.  It appears
   that the leading edge of this jet will continue to gradually nose
   into the base of broad downstream troughing, with one strengthening
   embedded mid-level perturbation digging southeast of the Canadian
   Prairies through the upper Great Lakes region, accompanied by a
   modestly deep surface cyclone.  

   At the same time, though, potentially cool surface ridging appears
   likely to be maintained across much of the Gulf Coast and Gulf of
   Mexico vicinity, beneath a persistent confluent regime to the
   west/southwest of the Eastern mid/upper troughing.  This will
   continue to inhibit boundary-layer moistening over the northern Gulf
   of Mexico, and preclude a substantive inland return flow of
   moisture.

   Various model forecast soundings, and other output, do suggest that
   mid-level moistening and lift, driven by warm advection in advance
   of the digging short wave impulse, will develop across and
   east-southeast of the lower Ohio Valley, through the Cumberland
   Plateau and adjacent portions of the Appalachians Wednesday
   afternoon and evening.  It appears that this may contribute to very
   weak destabilization supportive of convective development, but it
   remains unclear whether thermodynamic profiles will become conducive
   to charge separation supportive of lightning.

   In lower latitudes, (to the south of the mid-level ridging) broad
   weak mid/upper troughing, with a number of embedded perturbations,
   will also linger across the subtropical eastern Pacific into
   northern Mexico.  Models suggest that moistening and destabilization
   along the Sierra Madre Occidental into the northern Mexican plateau
   region will become supportive of scattered thunderstorms Wednesday
   afternoon and evening.  However, it currently appears that any
   appreciable risk for thunderstorms will remain well south and west
   of the international border.

   ..Kerr.. 11/30/2021

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