Day 4-8 Severe Weather Outlook Issued on Dec 1, 2017
Updated: Fri Dec 1 07:40:03 UTC 2017
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 04, 2017 - Tue, Dec 05, 2017
D7
Thu, Dec 07, 2017 - Fri, Dec 08, 2017
D5
Tue, Dec 05, 2017 - Wed, Dec 06, 2017
D8
Fri, Dec 08, 2017 - Sat, Dec 09, 2017
D6
Wed, Dec 06, 2017 - Thu, Dec 07, 2017
(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 010738
SPC AC 010738
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0138 AM CST Fri Dec 01 2017
Valid 041200Z - 091200Z
...DISCUSSION...
The mid/upper pattern will amplify considerably next week, as a deep
trough develops across the eastern US and heights build over the
western US. This transition will bring a cold, continental air mass
to many locations east of the Rockies during the second half of the
week, significantly reducing severe potential from D5/Tuesday
onward. However, before then, some potential exists for a strongly
forced band of convection along the cold front, perhaps from
portions of the southern Plains / Ozarks northward to the mid
Mississippi Valley. While surface-based buoyancy is unlikely to be
higher than 500-750 J/kg in any one location, northward moisture
return should be sufficient for at least weak buoyancy. Medium-range
guidance depicts differences in the amplitude of a shortwave trough
advancing across the central US though, such that mid-level lapse
rate forecasts remain uncertain, considerably impacting forecast
CAPE. Therefore, while no highlights are introduced at this time for
D4/Monday, considering the strength of the wind field, buoyancy on
the higher end of the forecast spectrum would likely necessitate
severe probabilities in later forecasts.
..Picca.. 12/01/2017
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