Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 030315

Area Forecast Discussion
National Weather Service Charleston SC
1015 PM EST Fri Dec 2 2016

High pressure will prevail through Saturday. A storm system will
affect the area Sunday through Tuesday. A strong cold front will
sweep through late next week.


Tonight: The area will remain positioned between a mid/upper lvl trough
off the Northeast coast and a mid/upper lvl ridge centered over the
Caribbean. At the sfc, dry high pressure centered to the northwest
will continue to expand over the region through the overnight period.
The pattern will result in modest radiational cooling under a light
northerly or calm wind. Given the setup, temps should dip into the
mid/upper 30s away from the coast. However, temps could stay a degree
or two warmer should cirrus continue to expand across the Southeast
late tonight. Closer to the coast, marine influences will help keep
temps in the low 50s.


Overview: The pattern will begin to become more active and unsettled
toward the later part of the weekend and early next. Deep layer
ridging will hold on for Saturday, then begin to shift eastward
Sunday as the next upper low and associated surface low take shape
over northwest Mexico.  This system will make its way east-northeast
later Sunday and Monday, which is expected to significantly increase
rain chances.

Saturday...Deep layer ridging will be over the area, which will
continue the cool, dry conditions for one more day. Skies will start
off mostly sunny, then there will be increasing mid/high clouds
late. Temperatures a little below normal, in the lower to mid 60s
with light northeast winds.  Saturday night...Deep layer moisture
will continue to slowly increase from the west ahead of the strong
upper low over northwest Mexico. Have continued trend of slight
chance to low end chance pops, mainly extreme west, by late in the
night. Lows still quite cool, in the lower to mid 40s most areas.
Lows could be a tad warmer if clouds come in thicker and faster than
currently forecasted.

Sunday...Models are in a bit of disagreement by this period
concerning the exact placement and timing of the deep moisture and
rain chances. Consensus would indicate that the first part of the
day would be mostly dry, then a more significant increase in rain
chances/pops later in the day. Have kept increasing trend into
chance level pops for later in the day. Think precip will be
generally in the form of light rain, but there could be some heavier
pockets. Lows ranging from upper 40s north to mid 50s south. Again,
lows could be a tad warmer depending on how much southerly low level
flow develops. Have gone likely pops most areas except over the
Atlantic waters.

Monday...A very tricky forecast as this point. Global models show a
strong surface low will move into the lower MS River Valley by late
day. However, ahead of it, they are also indicating that a weak
wedge could redevelop north of the area, which will cause winds to
back to east-northeast. Either way, expect rain/showers to be around
most of the day and have kept likely pops. Temperatures will be
difficult given the potential for a wedge. Have kept a sharp
north/south gradient, with lower 60s north to lower 70s south.

Rainfall totals: GFS and ECMWF Model QPF leaning toward relatively
significant rainfall amounts for much of the area through Monday.
Could see as much as 1/2 to 1 inch north and western zones, and less
over the extreme southeast. However, confidence on QPF values are
not high at this point, but looking like a reasonable chance to get
more than we have received in nearly two months.


The primary shortwave will lift northeast through the TN Valley
Monday night, pushing a cold front through the area on Tuesday
and bringing an end to the ongoing precipitation. A fairly mild
high pressure airmass will prevail Tuesday night into Wednesday
before a cold front approaches late week. There are considerable
model differences with the late week front, especially concerning
precip amount/coverage. Potential exists for a marked cooldown
on Friday.


VFR conditions are expected at both CHS and SAV terminals through
00Z Sunday.

Extended Aviation Outlook: VFR through Saturday. A storm system
and associated precipitation will likely produce periods of
flight restrictions Sunday through Tuesday.


Tonight: High pressure will expand across the coastal waters through
the overnight period with a pressure gradient that supports below
Small Craft Advisory level conditions. However, a modest surge
should occur as cooler air advects over northern waters tonight.
Winds should peak between 10-15 kt with gusts up to 20 kt, highest
beyond 15 nm in northern South Carolina waters and offshore Georgia
waters. Seas will build no higher than 2-3 ft in nearshore waters
and 3-4 ft in offshore Georgia waters.

High pressure is expected to remain over the waters through Saturday.
High pressure will begin shifting offshore Sunday and early next week
as another storm system takes shape over northwest Mexico and potentially
tracks northeast across the Gulf Coast states and west of the area
early next week.

No highlights expected through Sunday. Increasing southerly winds
later Monday and Tuesday ahead of a cold front could result in Small
Craft Advisory criteria conditions for at least the offshore GA
waters. A more significant cold front may move through the water
beyond the period, later next week.




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