SPC AC 021242

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0742 AM CDT Tue Nov 02 2021

   Valid 021300Z - 031200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   The risk for severe thunderstorms appears minimal through tonight.

   ...Synopsis...
   The large-scale mid/upper pattern this period will be characterized
   by mean eastern troughing and western ridging, with amplification of
   the mean ridge through the period.  For now, a belt of westerlies
   across the Great Basin and Intermountain West is located south of
   the strongest part of the ridge over Canada.  An embedded shortwave
   trough -- evident in moisture-channel imagery from southern UT to
   northern Baja -- is forecast to move east-southeastward through the
   period.  This trough should reach the TX Panhandle, southeastern NM
   and the ELP/LRU area by 00Z, then weaken as it crosses the southern
   Plains in advance of a trailing perturbation now near the ID/UT/NV
   border confluence.

   Preceding that feature, elevated low-level warm advection, moisture
   transport, and marginally favorable lapse rates will enable buoyancy
   in icing/lightning-production layers over much of central/southern
   OK and west-central to north TX through the period.  This will
   support episodic and mostly isolated thunderstorms, mainly poleward
   of a surface frontal zone now located from the Arklatex to west-
   central TX and southeastern NM.  Isolated thunder also may occur
   from convection moving eastward to southeastward over a corridor
   from south-central WY to central CO, in a zone of large-scale lift
   ahead of the current ID/UT/NV perturbation.  A few lightning strikes
   also may be noted with convection that will be relatively shallow,
   but still potentially accessing steep low/middle-level lapse rates
   and suitable lightning-generation layers in the lee of parts of the
   Great Lakes.

   ...TX Davis Mountains/Big Bend region...
   A conditional and isolated convective/severe threat may develop this
   afternoon just downshear from the Davis/Chisos Mountains corridor
   this afternoon.  Strong veering of wind with height near the front
   contributes to effective-shear magnitudes of 40-50 kt in forecast
   soundings, which also show a brief period of minimal MLCINH during
   mid/late afternoon's warmest period.  Any convection that can
   develop off the higher terrain and sustain itself east-northeastward
   over or near the Big Bend area may evolve into a supercell. 
   However, given that the mid/upper perturbation times slowly with
   respect to this area, with related large-scale lift lagging to the
   north/northwest, and the very localized, uncertain potential for
   convection to mature into stronger capping to the east, the
   potential appears too conditional for a categorical outlook area at
   this time.  Mesoscale diagnostic and prognostic trends will be
   monitored for a more-confident storm genesis/maintenance scenario.

   ..Edwards.. 11/02/2021

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