Dec 22, 2021 0700 UTC Day 2 Convective Outlook
Updated: Wed Dec 22 06:00:10 UTC 2021 (20211222 0700Z Day 2 shapefile | 20211222 0700Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20211222 0700 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20211222 0700 UTC Day 2 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 2 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20211222 0700 UTC Day 2 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 2 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20211222 0700 UTC Day 2 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 2 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 220600

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1200 AM CST Wed Dec 22 2021

   Valid 231200Z - 241200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Isolated lightning is possible early in the day across coastal parts
   of the Oregon and California, and late overnight near the WA
   coastline.

   ...Synopsis/Discussion...
   In mid/upper levels, the CONUS subset of the large-scale to synoptic
   pattern will deamplify through the period, except for persistent
   troughing near and offshore from the Pacific Coast.  Within that
   troughing, a strong shortwave perturbation and accompanying/compact
   cyclone are apparent in moisture-channel imagery west of the central
   BC coastline, northwest of Vancouver Island.  This feature should
   move southeastward as an amplifying open-wave trough, phasing with
   an initially separate, positively tilted trough/low now located well
   west of northern CA/OR.  By 23/12Z, the combined trough should
   extend from southern BC across the Olympic Peninsula.  

   This trough will split back into two branches through the period, as
   another approaches from the eastern Gulf of Alaska.  The northern
   branch will pivot eastward over the northern Rockies, ID and
   northern Great Basin, weakening considerably.  The southern branch
   should move southeastward over the Pacific west of CA, with the
   strongest vorticity and large-scale DCVA/lift remaining well
   offshore.  Meanwhile, the upstream perturbation -- currently located
   east of the Kamchatka Peninsula -- will approach the WA coastline
   with cooling midlevel temperatures atop the marine layer.  The main
   change for this outlook cycle was to extend the coastal thunder line
   -- already covering isolated potential with the first perturbation
   -- northward toward a regime of late-period low/middle-level
   destabilization ahead of the second Pacific trough.  Forecast
   soundings in both regimes indicate only around 50-250 J/kg MUCAPE,
   some of which may extend into suitable icing layers for lightning
   generation, with greatest buoyancy offshore.

   ..Edwards.. 12/22/2021

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z