Day 4-8 Severe Weather Outlook Issued on Nov 20, 2021
Updated: Sat Nov 20 07:59:03 UTC 2021
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 5 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 6 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 7 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 8 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4
Tue, Nov 23, 2021 - Wed, Nov 24, 2021
D7
Fri, Nov 26, 2021 - Sat, Nov 27, 2021
D5
Wed, Nov 24, 2021 - Thu, Nov 25, 2021
D8
Sat, Nov 27, 2021 - Sun, Nov 28, 2021
D6
Thu, Nov 25, 2021 - Fri, Nov 26, 2021
(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 200757
SPC AC 200757
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0157 AM CST Sat Nov 20 2021
Valid 231200Z - 281200Z
...DISCUSSION...
Consensus within the medium-range guidance suggests a deep upper
trough will be in place from central Quebec southward along the
Eastern Seaboard early D4/Tuesday morning. Upper ridging is expected
in the wake of this trough over the central CONUS with upper
troughing over the western CONUS. This trough/ridge/trough is
forecast to progress eastward, with the westernmost trough resulting
in a broadly cyclonic pattern over the western CONUS on D4/Tuesday
and D5/Wednesday. Some deepening/amplification of this troughing is
expected late D5/Wednesday into D6/Thursday, with the latest
guidance suggesting the development of a closed circulation off the
coast of the Baja Peninsula.
Moisture return is anticipated across the southern Plains on
D5/Wednesday and D6/Thursday ahead of a shortwave trough embedded
within the larger parent trough. Showers and thunderstorms currently
appear likely across portions of the southern Plains and on
D6/Thursday as this shortwave and associated cold front interact
with the increasing moisture/buoyancy. Run-to-run variability
limits forecast confidence after D6/Thursday, but the latest
guidance currently indicates low potential for severe storms on
D7/Friday and D8/Saturday.
..Mosier.. 11/20/2021
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