Day 4-8 Severe Weather Outlook Issued on Dec 18, 2020
Updated: Fri Dec 18 09:29:03 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, Dec 21, 2020 - Tue, Dec 22, 2020
D7
Thu, Dec 24, 2020 - Fri, Dec 25, 2020
D5
Tue, Dec 22, 2020 - Wed, Dec 23, 2020
D8
Fri, Dec 25, 2020 - Sat, Dec 26, 2020
D6
Wed, Dec 23, 2020 - Thu, Dec 24, 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 180927
SPC AC 180927
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CST Fri Dec 18 2020
Valid 211200Z - 261200Z
...DISCUSSION...
Latest medium-range guidance is in relatively good agreement that
upper ridging over the western CONUS on D4/Monday will move eastward
across the central and eastern CONUS on D5/Tuesday and D6/Wednesday.
Deep upper troughing is expected to develop across the Plains on
D6/Wednesday in the wake of the upper ridging. Further deepening is
anticipated as this upper trough continues eastward over the eastern
CONUS on D7/Thursday.
A strong cold front is forecast to accompany this upper trough. This
front is currently expected to move through much of the Plains on
D5/Tuesday, the MS, TN, and OH Valleys on D6/Wednesday, and off the
East Coast D7/Thursday. Moisture return ahead of the upper trough
and attendant cold front is currently expected to be modest and
confined to central/east TX and the Lower MS Valley. This limited
moisture return will temper severe potential. However, subtle change
in timing could result in higher potential, particularly given the
anticipated strength of the system.
..Mosier.. 12/18/2020
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