Day 4-8 Severe Weather Outlook Issued on Nov 26, 2020
Updated: Thu Nov 26 09:02:02 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
Sun, Nov 29, 2020 - Mon, Nov 30, 2020
D7
Wed, Dec 02, 2020 - Thu, Dec 03, 2020
D5
Mon, Nov 30, 2020 - Tue, Dec 01, 2020
D8
Thu, Dec 03, 2020 - Fri, Dec 04, 2020
D6
Tue, Dec 01, 2020 - Wed, Dec 02, 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 260900
SPC AC 260900
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CST Thu Nov 26 2020
Valid 291200Z - 041200Z
...DISCUSSION...
It appears increasingly probable that a closed upper low over the
southern Plains will merge with a northern-stream upper trough over
the eastern CONUS on Day 4/Sunday, likely forming a highly amplified
upper trough/low by Day 5/Monday. Medium-range guidance is in
reasonably good agreement in depicting a deepening surface low
developing from coastal LA Sunday morning northeastward to the
Mid-Atlantic vicinity by Day 5/Monday.
As greater low-level Gulf moisture advances inland across parts of
the Southeast and Mid-Atlantic in tandem with the deepening surface
low, weak instability may develop across the warm sector of this
cyclone. Rapidly strengthening low and mid-level wind fields suggest
that organized severe storms capable of producing at least isolated
damaging winds may occur over parts of the Deep South into the
Carolinas on Day 4/Sunday, and from the Carolinas into eastern
portions of the Mid-Atlantic on Day 5/Monday.
At this point, it remains very uncertain how much surface-based
instability will ultimately develop across these regions, which will
have a large impact on overall severe potential. This uncertainty
precludes the introduction of 15% severe probabilities for now.
However, the severe potential for this system will be reevaluated in
later outlook updates. Once the cold front associated with this
cyclone clears the East Coast, severe thunderstorm potential appears
minimal across the CONUS on Day 6/Tuesday and Day 7/Wednesday.
..Gleason.. 11/26/2020
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