Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 130504
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1204 AM EST Wed Dec 13 2017

.SYNOPSIS...
Dry high pressure will build across the region tonight and will
remain through Thursday. Another cold front will push into the
area Friday while low pressure passes offshore. High pressure
will return Saturday and persist into Sunday before a cold
front approaches the area early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
No major changes were made for the early morning update.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
Wednesday and Thursday: The mid/upper levels will consist of a
trough over the eastern half of the country. At the surface,
broad high pressure generally located over the Lower MS Valley
Wednesday morning will move over FL Wednesday night, then
offshore Thursday. The air mass is dry with PWATs no more than
0.5". As for temperatures, despite sunny skies, cold air
advection will lead to below normal temperatures Wednesday and
Wednesday night. Temperatures will moderate closer to normal
Thursday and Thursday night as cold air advection wanes. Also,
expect it to be breezy along the coast Wednesday night due to a
strong gradient.

Friday: The mid/upper levels still consist of a trough over the
eastern half of the country, with a wave/disturbance stretching
from the Great Lakes region into TX in the morning. This
wave/disturbance will move eastward as the day progresses. A
weak low is forecasted to form offshore late in the day. Models
continue to indicate weak lift and little moisture across the
area, increasing slightly further offshore. As a result, we have
slight chance POPs along the immediate coast late in the
afternoon. Very little QPF, if any, is expected. Highs will be
near normal with increasing clouds.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Dry and slightly cooler high pressure will build over the
Southeast Friday night into Saturday, leading to temps in the
low/mid 30s Friday night under clear skies and highs in the
mid/upper 50s Saturday afternoon. High pressure will then become
centered over the area Saturday night, leading to strong
radiational cooling and temps that dip into upper 30s to lower
40s. Conditions will be noticeably warmer on Sunday as a light
southerly wind develops on the west side of high pressure
shifting offshore. Temps should approach the low/mid 60s Sunday
afternoon. The next chance of showers should begin Sunday night
and increase into Monday as a plume of moisture characterized by
PWATs near 1.5-1.75 inches advects over the Southeast
along/ahead of a cold front that shifts through the area Monday
evening. Temps should be fairly warm ahead of the front, peaking
in the upper 60s to near 70 Monday afternoon.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
VFR.

Extended Aviation Outlook: Low chance of MVFR Friday as low
pressure passes offshore.

&&

.MARINE...
Winds are still gusting to gale force at 41004 and to near gale
force at 41008. Winds have likely peaked so it is too late to
issue a Gale Warning for the Georgia offshore leg. Winds will
continue to diminish through daybreak. Will maintain flags for
all legs through the night.

Wednesday through Saturday: High pressure will build towards
the waters Wednesday. A brief increase in the pressure gradient
will lead to elevated winds and building seas Wednesday night.
Small Craft Advisories may be needed for all of the waters at
this time. Thursday, the gradient decreases, allowing winds/seas
to trend downward. Friday, winds/seas will deteriorate as the
pressure gradient tightens along/near a cold front that pushes
over coastal waters by Friday night. Small Craft Advisories will
be possible for most of the coastal waters near and behind the
front Friday evening and night. High pressure should then build
over the waters Saturday with conditions that remain below Small
Craft Advisory levels.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Lake Wind Advisory until 5 AM EST early this morning for
     SCZ045.
MARINE...Small Craft Advisory until 10 AM EST this morning for AMZ350-
     352-354-374.
     Small Craft Advisory until 5 AM EST early this morning for
     AMZ330.

&&

$$


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