(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.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 190857
SPC AC 190857
Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0257 AM CST Thu Jan 19 2017
Valid 221200Z - 271200Z
CORRECTED TO ADD MISSING WORD
...Southeast Atlantic coast Sunday/day 4...
Substantial cyclogenesis is expected, generally in the immediate lee
of the southern Appalachians, Sunday into Monday morning as a strong
mid-upper shortwave trough traverses the Southeast and Gulf basin.
There are some differences in the details regarding the cyclogenesis
and lingering influences of a lead speed max early in the period.
However, the scenario still appears favorable for a squall line to
form along or in advance of the synoptic cold front which will then
move across parts of FL/GA and the Carolinas. Given an established
moist boundary layer across the Gulf basin already, an unstable warm
sector appears likely in advance of the cold front. Given
weak-moderate buoyancy and very strong low-midlevel vertical shear
in the warm sector, there will be the potential for substantial
severe weather, especially across parts of GA/FL where instability
will be less in question.
...Day 5/Monday and beyond...
In the wake of the strong cyclone/cold front, only limited moisture
return is expected ahead of another cold front that will approach
the Gulf coast days 6-7, along the southern fringe of a
positive-tilt upper trough.
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