Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 110249

Area Forecast Discussion
National Weather Service Charleston SC
949 PM EST Sun Dec 10 2017

High pressure will linger over the region through early
Tuesday. A dry cold front will sweep across the region Tuesday
afternoon, followed by a cool and dry air mass into late week.
A weak cold front will then push through the area on Friday.


Hourly temps can be difficult to pin down due to very minor
"puffs" of wind will cause temps to rise several degrees,
whereas when winds go calm temps will hold steady or continue
their slow decline. Overall the forecast is on track. Keep in
mind that the NWS Charleston Frost/Freeze program ended for the
season on November 30th, and will restart again on March 1,

Clear skies and cold weather will again prevail, with yet
another night of sub-freezing temps to develop across much of
the region near and inland from US-17. However, since the
geostrophic winds are as high as 15-20 kt, ideal radiational
cooling will not occur. Even so, expect lows a good 8-10F below


Monday, H85 winds will remain NW and downsloping across the
foothills of the Carolinas around daybreak. However, winds are
forecast to back from the SW during the daylight hours. A shallow
sfc lee trough is expected to persist through the daylight hours
Monday. The combination of the lee trough to the west and high
pressure to the south should support SW winds over the CWA. The
return flow is expected to result in WAA, with 1000MB-850MB
thickness increasing by 10M from 12Z-0Z. High temperatures in the
mid to upper 50s should be common, remaining around 5 degrees below

Tuesday, short range models indicate that a dry cold front will push
over the southern Appalachians during the early morning hours. The
cold front is expected to slide over the forecast area during the
afternoon hours, resulting in winds to shift from SW to NW and
become gusty. High temperatures in the upper 50s to near 60 should
be reached during the early afternoon, then gradually cool. Forecast
soundings only hint at thin cirrus level moisture associated with
the front. Tuesday night, H85 CAA lowers temps over KCHS from 0C at
0Z to -8C at 12Z. Low temperatures should easily fall below freezing
inland to near freezing along the coast.

Wednesday, sfc NW are forecast to continue through the morning
hours, then shifting from the SW with speeds 5 kts or less. NAM12
indicates that H85 temps will recover steadily during the day,
especially across SE GA. Using a blend of MOS, high temperatures are
forecast to range from the low 50s within the Altamaha River Valley
to the upper 40s north.


Dry high pressure will prevail over the Southeast into late week
with gradually modifying temps under sunny skies well in advance of
a trough of low pressure digging over the Central United States and
Midwest. In general, highs should range in the mid/upper 50s
Thursday, then upper 50s/lower 60s Friday. A cold front could bring
a few showers to the area Friday afternoon/evening before dry high
pressure prevails for the remainder of the weekend. Trends indicate
near normal temps late weekend into early next week ahead of another
cold front approaching the Southeast.


VFR at KCHS/KSAV through 00Z Tuesday.

Extended Aviation Outlook: VFR conditions are forecast to continue
across the terminals through late this week.


Tonight: High pressure centered in southern Texas will extend
east across the local waters. There is decent mixing that occurs
to keep westerly winds as high as 12-18 kt in the Atlantic and
around 10 kt in Charleston Harbor. Seas will be held to no more
than 2-4 ft within the offshore fetch.

The region is forecast to remain between high pressure to the south
and east and a lee trough over the western Carolinas on Monday. This
pattern will support steady SW winds. Wave heights are forecast to
range from 1-2 feet within 20 NM to 2-3 feet closer to 60 NM.

A dry cold front is expected to sweep across the marine zones late
Tuesday afternoon into the evening. Winds in the wake of the front
should increase from the NW, gusts are forecast to reach 25-30 kts
Tuesday night. Seas will increase to 4-6 feet across the outer GA
waters Tuesday night into Wednesday. Small Craft Advisories will
likely be needed outside of the CHS Harbor.

Sfc high pressure should return to the region Wednesday and Thursday,
providing conditions below Small Craft Advisory criteria.




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