Day 4-8 Severe Weather Outlook Issued on Dec 19, 2020
Updated: Sat Dec 19 09:53:03 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
Tue, Dec 22, 2020 - Wed, Dec 23, 2020
D7
Fri, Dec 25, 2020 - Sat, Dec 26, 2020
D5
Wed, Dec 23, 2020 - Thu, Dec 24, 2020
D8
Sat, Dec 26, 2020 - Sun, Dec 27, 2020
D6
Thu, Dec 24, 2020 - Fri, Dec 25, 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 190951
SPC AC 190951
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CST Sat Dec 19 2020
Valid 221200Z - 271200Z
...DISCUSSION...
Medium-range guidance continues to forecast significant
amplification of a shortwave trough moving out of the Pacific
Northwest D4/Tuesday. Forecast guidance suggests this shortwave
deepens as it moves over the Plains on D5/Wednesday and continues
maturing over the eastern CONUS on D6/Thursday. Very strong
mid-level flow will develop around this upper trough, with a very
deep surface low and strong cold front also anticipated.
Main uncertainties are the speed of the system's eastward
progression and the quality of the moisture return ahead of the cold
front. Current guidance would suggest some low-probability severe
potential does exist on D5/Wednesday and D6/Thursday, but limited
moisture return is forecast to limit a more widespread severe
threat.
..Mosier.. 12/19/2020
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