Day 4-8 Severe Weather Outlook Issued on Dec 20, 2020
Updated: Sun Dec 20 09:46:02 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
Wed, Dec 23, 2020 - Thu, Dec 24, 2020
D7
Sat, Dec 26, 2020 - Sun, Dec 27, 2020
D5
Thu, Dec 24, 2020 - Fri, Dec 25, 2020
D8
Sun, Dec 27, 2020 - Mon, Dec 28, 2020
D6
Fri, Dec 25, 2020 - Sat, Dec 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 200944
SPC AC 200944
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CST Sun Dec 20 2020
Valid 231200Z - 281200Z
...DISCUSSION...
Deep upper troughing is expected to be in place over the western and
central CONUS early D4/Wednesday. This upper troughing is then
expected to progress eastward as an embedded shortwave trough moves
across the central Plains. Another shortwave is forecast to follow
quickly in the wake of the first, moving across the southern Plains
D4/Wednesday night.
By early D5/Thursday, a deep upper trough will likely extend from
Ontario southward into the southern Plains, with strong flow aloft
surrounding it. Continue eastward motion is expected into D6/Friday,
with further deepening/maturing of the system.
Some severe potential appears possible across central/east TX into
the Lower MS Valley on D4/Wednesday as the cold front moves through,
and the Carolinas/southern VA late D5/Thursday or early D6/Friday.
However, in both cases, instability is expected to be modest, which
will limit coverage. Additionally, differences in timing within the
guidance results in uncertainty regarding location. These factors
limit predictability. Stable conditions are currently forecast after
D6/Friday.
..Mosier.. 12/20/2020
CLICK TO GET WUUS48 PTSD48 PRODUCT
weather.gov 
@NWSSPC
