Nov 27, 2021 1630 UTC Day 1 Convective Outlook
Updated: Sat Nov 27 16:21:27 UTC 2021 (20211127 1630Z Day 1 shapefile | 20211127 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20211127 1630 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
20211127 1630 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
20211127 1630 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
20211127 1630 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 271621

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1021 AM CST Sat Nov 27 2021

   Valid 271630Z - 281200Z

   ...NO THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Thunderstorms are not expected across the contiguous United States
   through early Sunday.

   ...Synopsis...
   Within the southern stream of the mid-level westerlies, a weak upper
   low over northern Mexico and West Texas will transition to an open
   shortwave trough as it moves east and is absorbed by a larger
   synoptic trough over the northeastern CONUS. At the surface, a cool
   post-frontal airmass over central and southern Texas will undergo
   minimal modification through the day, with widespread showers and
   cloud cover limiting diurnal heating north of the remnant coastal
   front. Regional observed and model soundings show generally weak
   lapse rates, less than 6.5 C/km, through the column despite cooling
   temperatures aloft. The net effect will be insufficient buoyancy
   available for updrafts capable of lightning as the core of the
   shortwave trough moves over south Texas this afternoon and evening.
   A secondary cold front and weak cyclogenesis along the coastal front
   will reinforce offshore flow as cold air ahead of strengthening
   surface high pressure over the interior CONUS will scour remaining
   moisture late tonight into early Sunday, precluding thunderstorm
   development over the CONUS.

   ..Lyons/Grams.. 11/27/2021

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z