Nov 20, 2021 0600 UTC Day 1 Convective Outlook
Updated: Sat Nov 20 05:47:12 UTC 2021 (20211120 1200Z Day 1 shapefile | 20211120 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20211120 1200 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
20211120 1200 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
20211120 1200 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
20211120 1200 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 200547

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1147 PM CST Fri Nov 19 2021

   Valid 201200Z - 211200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Severe thunderstorms are not forecast across the contiguous United
   States on Saturday.

   ...Discussion...
   Modest amplification of the upper flow field over the U.S. will
   occur today, as a weak/positively tilted trough over the
   Intermountain West shifts eastward, and eventually begins to
   interact/phase with a stronger feature within the polar stream
   digging southeastward across the Canadian Prairie.

   At the surface, high pressure will continue to prevail over the
   east, while a reinforcing cold front -- at the leading edge of a
   cold Canadian airmass -- moves into the north-central U.S.
   overnight.

   Thunder potential across most of the country remains negligible.  A
   lightning flash or two may occur over the Colorado vicinity as the
   upper trough passes, and a few flashes could occur late, over the
   Ozarks/mid Mississippi Valley vicinity in a zone of weak low-level
   warm advection.  The area where thunder appears most likely remains
   confined to portions of the southern half of Florida, where a higher
   theta-e boundary layer airmass will remain in place through the
   period.

   ..Goss/Weinman.. 11/20/2021

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