Day 4-8 Severe Weather Outlook Issued on Dec 8, 2020
Updated: Tue Dec 8 09:49:02 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
Fri, Dec 11, 2020 - Sat, Dec 12, 2020
D7
Mon, Dec 14, 2020 - Tue, Dec 15, 2020
D5
Sat, Dec 12, 2020 - Sun, Dec 13, 2020
D8
Tue, Dec 15, 2020 - Wed, Dec 16, 2020
D6
Sun, Dec 13, 2020 - Mon, Dec 14, 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 080947
SPC AC 080947
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CST Tue Dec 08 2020
Valid 111200Z - 161200Z
...DISCUSSION...
A large-scale upper trough with several embedded shortwave troughs
will slowly migrate across the Plains and central U.S. Days
4-5/Fri-Sat. Strong southwesterly flow amid height falls will result
in a strengthening surface low developing northeast from the
southern Plains early on Friday to the lower Great Lakes vicinity by
Day 6/Sun morning. Low level Gulf return flow will spread moisture
northward ahead of a cold front attendant to the low. Better-quality
moisture will be confined to the TX Gulf Coast eastward to the lower
MS Valley and thunderstorms are likely to increase by Friday
afternoon along the front. Some low-end severe threat could develop
from east TX into the lower MS Valley through Saturday, but
uncertainty remains regarding how much destabilization will be able
to occur whether moisture return will be ill-timed with the frontal
passage/strongest forcing.
Beyond Day 5/Sat, medium range guidance varies greatly in the
evolution of the larger-scale trough over the central U.S. and
predictability is low.
..Leitman.. 12/08/2020
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