(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 160834
SPC AC 160834
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0234 AM CST Sun Dec 16 2018
Valid 191200Z - 241200Z
...DISCUSSION...
Latest medium-range models continue to suggest a very active pattern
will develop over the CONUS during the upcoming day4-8 time frame.
One significant mid-level speed max/short-wave trough is forecast to
eject across TX into the lower MS Valley region Wednesday. This
feature may induce weak convection near the central Gulf coast day4.
However, models are in general agreement that a much deeper upper
trough is forecast to develop over the Gulf States by Thursday with
substantial height falls expected to 25N latitude which may allow
for air mass recovery downstream across portions of FL into coastal
Carolinas by day6. While large-scale pattern is generally agreed
upon, significant disruptive convection is likely to evolve over the
central/eastern Gulf basin prior to the trough's influence over FL.
Will not introduce 15% severe probs at this time over FL owing to
some degree of uncertainty regarding buoyancy; although,
strengthening shear profiles in advance of this strong trough do
warrant some concern for potential organized severe.
..Darrow.. 12/16/2018
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