Dec 24, 2021 2000 UTC Day 1 Convective Outlook
Updated: Fri Dec 24 19:59:19 UTC 2021 (20211224 2000Z Day 1 shapefile | 20211224 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20211224 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20211224 2000 UTC Day 1 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 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20211224 2000 UTC Day 1 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 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20211224 2000 UTC Day 1 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 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 241959

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0159 PM CST Fri Dec 24 2021

   Valid 242000Z - 251200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Isolated thunderstorms are possible over parts of the Pacific Coast
   States, eastern Great Basin and Colorado Plateau.

   ...20Z update...
   Limited changes to current overall thinking regarding western CONUS
   thunderstorm potential. The previously depicted thunderstorm area
   across the interior valleys of California has been removed owing to
   post-wave diminishing potential.

   Regarding the Midwest, a couple of lightning flashes could occur
   late tonight/early Saturday (prior to 12Z) across parts of Missouri
   into downstate portions of Illinois/Indiana. However, given the
   marginality of the thermodynamic environment, current expectations
   are for thunderstorm probabilities/coverage to remain below 10
   percent across this region.

   ..Guyer.. 12/24/2021

   .PREV DISCUSSION... /ISSUED 1014 AM CST Fri Dec 24 2021/

   ...Western States...
   Morning water vapor imagery shows two strong shortwave troughs
   affecting the western US today.  One system is currently moving
   ashore over southern CA, and has produced scattered lightning
   flashes during the past few hours offshore and just inland.  Radar
   and IR satellite imagery suggest that the main lift associated with
   this feature is beginning to shift eastward, with the prospects for
   more lightning over southern CA waning rapidly.  Have therefore
   removed that thunderstorm area with anticipated coverage now below
   10%.  This same system will move eastward and result in isolated
   thunderstorms today over the southern Sierras, and from northwest AZ
   into parts of UT/CO.

   A second shortwave trough is approaching the WA/OR coast.  Isolated
   thunderstorms are expected to occur along the coast through the
   afternoon, with lesser chances farther inland into parts of ID. 
   Present indications are that the eastern areas will see minimal
   coverage of flashes, so have opted to leave those areas below 10%
   threshold.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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