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000
FXUS62 KCHS 070331
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1031 PM EST Fri Dec 6 2019

.SYNOPSIS...
A weak disturbance will move through today. High pressure will
build from the northwest tonight through Sunday. A warm front
will lift north of the region Monday, before a cold front
sweeps through the area late Tuesday. Strong high pressure will
then return Wednesday through Friday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/..
As of 1025 PM: An isolated thunderstorm was tracking east about
50 nm off the Charleston County, over AMZ370. Returns across
Berkeley County were steadily decreasing. I will update the
forecast to adjust PoP and sky trends over the next several
hours. Temperatures are forecast to only cool by another 3-4
degrees before sunrise.

As of 850 PM: KCLX detected light returns across the I-26
corridor of the SC Lowcountry. Sfc observations indicate that
the returns were not associated with rainfall. However, I would
not be surprised to hear of a few sprinkles in the area. I will
maintain SCHC PoPs over the next couple of hours, then will drop
the mention of showers through the rest of the night.

As of 7 PM: KCLX detected several patches of light returns
across SE GA. Observation stations under the returns did not
observe rainfall at the sfc. I assume that the returns were
associated with wet mid-level clouds. I will update the
forecast to adjust sky and temperatures through this evening.

Previous Discussion:
This Evening: A mid-level short wave will move overhead while
deamplifying. Closer to the surface, lift associated with this
feature combined with a plume of PWATs stretching from the ocean
towards the Charleston Tri-County area will lead to scattered
showers in the evening. Models are in good agreement showing the
"heaviest" precipitation early, with both intensity and areal
coverage decreasing as the evening progresses. QPF should
generally be <0.01".

Tonight: The mid-level wave will quickly shift offshore. At the
surface, a weak cold front will approach from the north.
Though, models have it weakening/dissipating as it crosses
through our area. What may end up being more noticeably is
surface high pressure building behind the front late tonight.
Clouds should generally decrease, especially late. Temperatures
may be somewhat tricky, depending partly on the cloud cover.
Lows should generally be in the 40s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Dry high pressure will expand across the area from the
northwest on Saturday. The upper shortwave will be far enough
east initially to keep any inverted trough development well off
the coast. Therefore we do not anticipate any precipitation
Saturday.

A secondary shortwave will move into the Southeast Saturday
night and Sunday. The surface ridge will shift farther to the
east, pushing an inverted trough closer to the coast before it
lifts north Sunday night and Monday. A few rain showers could
skirt through northern areas Sunday night and Monday though most
areas will remain dry. A warm front will lift north on Monday.

Temps in the 60s Saturday and Sunday will warm well into the 70s
on Monday as a southerly flow develops.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The mid and upper trough will amplify to our west early next week,
allowing for a cold front to approach from the west late Tuesday,
which will likely pass through Tuesday night. There remain enough
timing differences between the global models to not show anything
higher than chance PoP ahead of the front, but higher chances will
be required at we draw closer to the event. Any t-storm risk is too
low to include this far in advance. Confidence is excellent that
it`ll be unseasonably warm, with H85 temps as great as 12-13C
Tuesday.

Behind the cold front a large and robust high pressure system with
dry and colder weather will dominate the local vicinity Wednesday
and Thursday, before it gives way to another upstream cold front
late in the week. An extended period of breezy to windy conditions
will prevail through the period with large pressure rises and a
tight gradient around the high.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Prior to the 0Z TAFs, KCLX detected several patches of light
returns across SE GA. Observation stations under the returns did
not observe rainfall at the sfc. I assume that the returns were
associated with wet mid-level clouds. High pressure centered
over the mid-Atlantic states will build south across the
forecast area late tonight through Saturday. Dry low levels will
support a VFR forecast. Winds will remain light to calm
tonight, then winds will become steady from the NE after sunrise
Saturday and remain through the day.

Extended Aviation Outlook: Overnight stratus will be possible
Sunday night through Wednesday night, possibly resulting in
flight restrictions.

&&

.MARINE...
Tonight: Initially, their won`t be much of a pressure gradient
across the waters, which will lead to light and variable winds.
However, later tonight, high pressure building in from the
north should increase the pressure gradient, causing winds to
turn to the north and increase to around 10 kt. Seas initially
1-2 ft could build a foot by daybreak Saturday.

A pinched northeast gradient on Saturday will result in the
onset of Small Craft Advisory conditions for all Atlantic waters
outside Charleston Harbor. We have SCA headlines beginning at
varying times Saturday or Saturday night. Conditions will
improve late Sunday across the nearshore waters due to a warm
front lifting through and southerly flow returning. SCA
conditions will persist over the offshore GA waters through much
of next week due to a combination of winds/seas.

Sea Fog: Conditions still point to at least a chance of sea fog on
Monday as temps and dew points climb greater than the underlying
waters. Should this occur the most likely time frame would be Monday
within a favorable S-SW fetch and before winds increase too much.
Confidence is not yet supportive of adding mention to the forecast,
nor to the Hazardous Weather Outlook.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from 6 PM Saturday to 5 PM EST Sunday for
     AMZ352-354.
     Small Craft Advisory from 8 AM Saturday to 6 AM EST Thursday
     for AMZ374.
     Small Craft Advisory from 8 AM Saturday to 5 PM EST Sunday for
     AMZ350.

&&

$$
NEAR TERM...NED
SHORT TERM...JRL
LONG TERM...
AVIATION...NED
MARINE...JRL