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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 180855
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
355 AM 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/...
As of 350 AM: Weak sfc high pressure will remain centered over 
FL today. To the west, low pressure is forecast to organize and 
deepen across the southern Great Plains. An associated warm 
front is expected to slowly lift north across the Deep South 
this afternoon and evening. As the front approaches, a few 
showers may develop across portions of SE GA late this 
afternoon. Using a blend of MOS, I will forecast high 
temperatures to range from the low to mid 60s across the SC 
Lowcountry to the upper 60s across the southern Altamaha River.

Tonight: The center of low pressure is expected to track NE across 
Arkansas, lifting a warm front across the forecast area. Near term 
guidance indicates that weak isentropic lift will develop in the 
vicinity of the warm front tonight. 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 /09Z FRIDAY THROUGH TUESDAY/...
Prior to the 6Z TAFs, IR satellite detected a wide area of
stratus approaching the terminals, greater coverage upstream of
KCHS. Patchy fog developed along many coastal areas prior to the
6Z TAFs. I would imagine that the arrival of the stratus will
make fog at the terminals less likely. I will maintain a TEMPO
between 9Z-13Z for 5SM BR. The rest of the TAF period should
feature BKN VFR cloud cover and SW winds. 

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...
Today and tonight: A warm front will approach the coast waters 
today, then slowly lifting across the area tonight. Winds will 
remain from the south between 5-10 kts. Seas will remain between 1 
to 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...NED
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...NED/JRL 
MARINE...NED/JRL 
TIDES/COASTAL FLOODING...JRL