Day 4-8 Severe Weather Outlook Issued on Dec 12, 2020
Updated: Sat Dec 12 09:05:02 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
Tue, Dec 15, 2020 - Wed, Dec 16, 2020
D7
Fri, Dec 18, 2020 - Sat, Dec 19, 2020
D5
Wed, Dec 16, 2020 - Thu, Dec 17, 2020
D8
Sat, Dec 19, 2020 - Sun, Dec 20, 2020
D6
Thu, Dec 17, 2020 - Fri, Dec 18, 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 120903
SPC AC 120903
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0303 AM CST Sat Dec 12 2020
Valid 151200Z - 201200Z
...DISCUSSION...
Medium-range model output suggests that initially northwest flow
across much of Canada will transition to a more zonal regime, while
a belt of westerlies emanating from the mid-latitude Pacific remains
a prominent influence across much of the U.S. through the middle and
latter portions of next week. As this occurs, it appears that an
initially amplified trough to the lee of the southern Rockies will
lose amplitude, with the most significant embedded perturbation
accelerating toward the Mid Atlantic, where it may support
significant surface cyclogenesis offshore Wednesday into Thursday.
An additional perturbation or two may follow within this stream,
inland across the Pacific coast and through the U.S. by early next
weekend. However, models indicate little in the way of substantive
surface cyclogenesis and inland return flow of moisture off the Gulf
of Mexico, resulting in the maintenance of generally stable
conditions and low convective potential.
..Kerr.. 12/12/2020
CLICK TO GET WUUS48 PTSD48 PRODUCT
weather.gov 
@NWSSPC
