Day 4-8 Severe Weather Outlook Issued on Nov 20, 2020
Updated: Fri Nov 20 09:50:03 UTC 2020
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
Mon, Nov 23, 2020 - Tue, Nov 24, 2020
D7
Thu, Nov 26, 2020 - Fri, Nov 27, 2020
D5
Tue, Nov 24, 2020 - Wed, Nov 25, 2020
D8
Fri, Nov 27, 2020 - Sat, Nov 28, 2020
D6
Wed, Nov 25, 2020 - Thu, Nov 26, 2020
(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 200948
SPC AC 200948
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CST Fri Nov 20 2020
Valid 231200Z - 281200Z
...DISCUSSION...
Organized severe thunderstorm potential appears low across the CONUS
on Day 4/Monday as a large-scale upper trough shifts eastward from
the western states to the Plains. Lee cyclogenesis should occur over
the central Plains ahead of the amplifying upper trough, with some
low-level moisture return occurring over the southern Plains. As the
southern portion of the upper trough consolidates and ejects
eastward across the southern Plains into the lower MS Valley and
Southeast from Day 5/Tuesday into Day 6/Wednesday, some severe
thunderstorm potential could materialize across parts of these
regions. At this point, instability appears fairly limited, which
should keep any severe threat isolated/marginal.
The upper trough may outpace the limited low-level moisture by Day
7/Thursday across parts of the eastern states, which suggests that
the severe risk will probably be lower compared to prior days. By
the end of next week, large differences emerge in medium-range
guidance regarding the evolution of another upper trough over the
western/central CONUS. Depending on this trough's amplification and
the degree of low-level moisture return, it appears possible that a
severe threat could develop across parts of the southern Plains
around Day 8/Friday. Regardless, predictability remains very low at
this extended time frame.
..Gleason.. 11/20/2020
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