SPC AC 131945

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0145 PM CST Mon Dec 13 2021

   Valid 132000Z - 141200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   A few thunderstorms will be possible across the eastern Florida
   Peninsula, and over parts of the West Coast and northern California.

   ...Discussion...
   Aside from a few minor tweaks to the southern portion of the western
   U.S. thunder area, no changes appear necessary to the outlook at
   this time.

   ..Goss.. 12/13/2021

   .PREV DISCUSSION... /ISSUED 1020 AM CST Mon Dec 13 2021/

   ...Northern CA...
   Upper pattern will amplify today across the western CONUS as heights
   rise from the central High Plains into British Columbia ahead of a
   strong shortwave trough approaching the northern/central CA coast.
   Surface low associated with this shortwave trough is currently
   centered just off the central/southern OR coast. This low is
   expected to deepen throughout the day while gradually moving
   north-northeastward. A strongly forced frontal band associated with
   this system is forecast to move southeastward throughout the day,
   moving first through southwest/south-central OR and adjacent far
   northern CA later this morning before then moving through more of
   northern CA and the Bay Area later this afternoon/evening. 

   Buoyancy will be modest and relatively shallow, keeping updraft
   depth limited and likely precluding anything but isolated lightning
   flashes. Even with the limited buoyancy and updraft depth, strong
   low-level flow accompanying the frontal band could contribute to
   storm-scale cyclonic shear/rotation. This is particularly true
   across portions of Sacramento Valley east of the Bay Area, where
   channeled low-level flow will be more southerly, contributing to
   strong low-level vertical shear. Even so, given the weak buoyancy
   and limited low-level moisture, the overall threat appears too
   low/conditional to outlook any areas.

   ...Elsewhere...
   Dry and stable conditions are anticipated elsewhere across the
   majority of the central and eastern CONUS. The only exception is
   over the east-central FL coast, where a few westward moving
   thunderstorms may reach the coast.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z