Day 4-8 Severe Weather Outlook Issued on Nov 18, 2021
Updated: Thu Nov 18 09:02:03 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
Sun, Nov 21, 2021 - Mon, Nov 22, 2021
D7
Wed, Nov 24, 2021 - Thu, Nov 25, 2021
D5
Mon, Nov 22, 2021 - Tue, Nov 23, 2021
D8
Thu, Nov 25, 2021 - Fri, Nov 26, 2021
D6
Tue, Nov 23, 2021 - Wed, Nov 24, 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 180900
SPC AC 180900
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CST Thu Nov 18 2021
Valid 211200Z - 261200Z
...DISCUSSION...
A large-scale upper trough should quickly amplify from Day 4/Sunday
into Day 5/Monday across the central/eastern CONUS. Moisture return
ahead of this feature is still expected to remain too meager to
support meaningful instability, and the potential for organized
severe thunderstorms should remain low. The consensus of latest
medium-range guidance continues to suggest that this upper trough
will become a closed low along/near the Mid-Atlantic Coast by Day
6/Tuesday. Regardless, a strong cold front associated with this
system will likely have moved well offshore from both the Atlantic
and Gulf Coast regions, with negligible severe potential evident.
Around the middle of next week, another upper trough may develop
over the western CONUS and advance towards the Rockies. Some
guidance indicates that substantial low-level moisture may return
northward across parts of the southern Plains (mainly parts of TX)
by Day 8/Thursday. If this occurs, then there may be enough
instability to support robust convection and potentially a severe
threat across this region. Regardless, confidence in the evolution
of this upper trough and in sufficient low-level moisture return
remains limited at this extended time frame, suggesting overall low
predictability.
..Gleason.. 11/18/2021
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