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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 181830
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
130 PM EST Fri Jan 18 2019

.SYNOPSIS...
High pressure will move offshore through tonight. A storm
system will impact the area Saturday night into Sunday,
followed by cold and dry high pressure early next week. A
strong cold front will affect the area Wednesday night into
Thursday. 

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: High pressure will prevail under a zonal flow aloft 
well ahead of a strengthening low pressure system tracking over the 
Central United States. Soundings indicate some moisture in the low-
lvls, sufficient to produce broken to overcast clouds this afternoon 
when combined with high clouds associated with an h25 jet aloft. 
However, breaks in cloud cover are occurring, which will allow
temps to warm more than the previous day. Moisture supply will 
struggle to deepen substantially throughout the day, but a 
subtle warm front should develop west of the region and potentially
help produce a few showers well inland across Southeast Georgia
late. Temps will gradually warm, especially with breaks in 
cloud cover. In general, high temps should range in the low/mid 
60s. Temps could approach the upper 60s south of I-16 in Southeast
Georgia.

Tonight: The center of low pressure west of the region is expected 
to track northeast across Arkansas, lifting the warm front north 
across the area. Near term guidance indicates that weak isentropic 
lift will develop in the vicinity of the warm front. CAMs generally 
show very sparse coverage of showers during the overnight hours. 
However, the operational guidance and WPC support SCHC PoPs across 
the inland counties. Low temperatures are forecast to range in the 
low to mid 50s.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
A potent storm system will move through the area Saturday night
with the cold front quickly sweeping offshore Sunday morning.
Ample moisture advection ahead of the front and considerable 
upper level divergence will support widespread showers 
accompanying the front with most areas picking up 0.25-0.50". We
maintained a slight chance of thunderstorms across coastal
southeast GA and the Atlantic waters where weak instability is
expected. Prior to the front's arrival, Saturday looks mainly
dry other than perhaps a few morning showers associated with the
warm front lifting north. Despite extensive cloud cover, strong
warm air advection will push high temps into the low 70s.

Cooler, drier conditions expected from late Sunday morning through 
Monday. Breezy conditions will develop on Sunday, potentially 
requiring a Lake Wind Advisory for Lake Moultrie. Highs on 
Sunday will be in the 50s while Monday will only be in the 40s.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
High pressure will prevail Monday night through Tuesday night,
then another system will likely bring another round of
precipitation to the area Wednesday night into Thursday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Tempo MVFR cigs are possible at both CHS and SAV for the next couple 
hours. Otherwise, VFR conditions should prevail mid afternoon into 
the evening before MVFR cigs return around 04-05z tonight with a 
warm front passing near the area. MVFR conditions should then persist
through 14z Saturday at both terminals, before winds become more
southerly and gust to 15-20 kt by 18Z Saturday.

Extended Aviation Outlook: MVFR, potentially IFR, expected 
Saturday evening into Sunday morning as numerous to widespread 
showers shift over the region with a cold front. Also, 
breezy/gusty winds expected Saturday afternoon through Sunday
morning.

&&

.MARINE...
This Afternoon and Tonight: High pressure will prevail over the 
coastal waters for much of the day, before a warm front approaches 
the coast late, then slowly lifts north across the area tonight. 
Conditions will remain well below small craft advisory levels 
through tonight. In general, west winds will turn more southerly 
late today and generally peak between 5-10 kt while seas range 
between 1-2 ft.

A strong southerly low-level jet will develop Saturday ahead of
a cold front. Small Craft Advisory conditions will become likely
by Saturday evening, continuing into the overnight hours. There
is a potential for brief Gale conditions over the offshore GA
waters late Saturday evening or early Sunday morning, primarily
in gusts. Another wind surge is expected Sunday afternoon
through Monday morning as cold air advection spreads over the
waters behind the cold front. Small Craft Advisories look nearly
certain, and there could be another brief period of Gale force
wind gusts beyond 15 nm from shore. High pressure will build
over the waters later Monday into mid/late week, resulting in
quiet conditions.

&&

.TIDES/COASTAL FLOODING...
Tide levels will be increasing this weekend through the middle
of next week due to astronomical factors. A positive tidal
anomaly is also possible due to wind forcing, potentially 
leading to minor coastal flooding with the morning high tides. 
The greatest chance for this to occur will be Saturday morning 
and Tuesday morning.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$
NEAR TERM...DPB
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...DPB/JRL
MARINE...DPB/JRL
TIDES/COASTAL FLOODING...