SPC AC 011257

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0657 AM CST Tue Feb 01 2022

   Valid 011300Z - 021200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Severe thunderstorms appear unlikely over the conterminous U.S.

   ...Synopsis/Discussion...
   A series of shortwaves at various latitudes will contribute to
   amplification of an extensive, yet progressive, trough from Arctic
   Canada across the western Hudson Bay region, then southwestward
   across the northern Plains to UT, southern CA and the Pacific west
   of Baja.  Meanwhile, a southern-stream perturbation is devolving
   from a closed cyclone to open-wave trough over the northwestern
   Gulf.  At the surface, 11Z analysis showed a cold front near a
   DSM-MKC-GAG-CVS line.  By the end of the period, the front should
   extend near a line from DTW-IND-MVN-DAL, then southwestward over the
   Edwards Plateau, Trans-Pecos area of TX, and southeastern/central
   NM.

   Isolated to scattered thunderstorms will remain possible over the
   open Gulf east and southeast of the mid/upper perturbation for much
   of today, until it weakens and passes the area tonight.  Activity
   should occur mainly in an arc of convection immediately ahead of the
   trough, and farther east in a zone of sustained low-level
   convergence, moisture transport and surface-based buoyancy. 
   Isolated thunderstorms are evident moving northward across the
   central/eastern LA shelf waters in the latter regime, and cannot be
   ruled out over nearby coastal areas.  

   Some model soundings' forecast mid/upper-level profiles show enough
   stability inland to cap convection to levels warmer than -20 C, as
   also evident in 12Z LCH/LIZ RAOBs.  However, only 1-2 deg C cooler
   conditions in the 400-500-mb layer above the warm-advection plume --
   or about that much warmer within the plume -- would be needed
   (compared to those models' soundings) to support an areal lightning
   threat over land.  RAP CAPE profiles over land, by contrast, do
   briefly intrude into the bottom of icing layers suitable for
   lightning production, near and east of an MCV now located southwest
   of LFT.  Buoyant layers over the Gulf also are deeper, given 30-40
   kft echo tops observed with isolated cells over shelf waters over
   the past couple hours, with warm advection expected toward land.  As
   such, a small general-thunder area has been added for daylight
   hours.

   ..Edwards.. 02/01/2022

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