ACUS03 KWNS 130820
SPC AC 130819
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 AM CST Thu Dec 13 2018
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ...MAINLY EARLY
SATURDAY...ACROSS PARTS OF EASTERN NORTH CAROLINA...
Strong thunderstorms may impact portions of eastern North Carolina
early Saturday, accompanied by at least some risk for severe
Models indicate little change to the general large-scale mid/upper
flow through this period, with several amplified waves progressing
through split branches of westerlies emanating from the mid-latitude
Pacific. The wave, including an embedded occluded cyclone, east of
the lower Mississippi Valley may remain the most prominent
perturbation over the interior United States. However, guidance
indicates that this system will be in the process of weakening by
Saturday. It is forecast to generally continue developing
east-northeastward toward the Mid Atlantic Coast region, but there
remains rather large spread among/within the deterministic and
ensemble model output concerning this movement.
It appears at least possible that the warm sector of a secondary
frontal wave/low may still be inland of the North Carolina coast at
12Z Saturday, before the wave migrates offshore by early afternoon.
Otherwise, low-level cooling/drying likely will be well underway
across much of the remainder of the Southeast and northwestern Gulf
...Eastern North Carolina...
The warm sector of the frontal wave appears likely to become fairly
moist, supported by moisture return from both the Gulf of Mexico and
western Atlantic, and this may contribute to weak to modest CAPE in
excess of 500 J/kg. Given this air mass, shear and forcing for
ascent near the wave will provide at least some potential for
organized convective development which may pose a risk for damaging
wind gusts, or perhaps a tornado or two. This may be a continuation
of overnight convection spreading northeastward through the coastal
plain, before advancing off shore early Saturday.