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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

                            
000
FXUS62 KCHS 211134
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
734 AM EDT Thu Mar 21 2019

.SYNOPSIS...
A cold front will move into the region from the west late today
and then offshore tonight. High pressure will then build into
the region and persist through the weekend. Low pressure may
move through the Southeast on Tuesday. 

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: A complex mid/upper level trough will swing through the 
southeast states today. All of the significant moisture will 
head away from the region to the north as surface low pressure 
lifts north along the Mid Atlantic Coast. A dry cold front is 
expected to race into the I-95 corridor by late day. This 
morning we expect the low clouds across SC to scour out by mid 
morning with mostly sunny skies across the region from late 
morning onward. Southwest to west winds are expected to increase
along and ahead of the cold front this afternoon with a brief 
period of 15-25 mph breezes likely, especially across Southeast 
GA and coastal SC. 

Tonight: The cold front is expected to move offshore by early
evening with the atmosphere too dry to expect any brief showers
across northern SC zones. There should be a brief period of mid
clouds then skies will become mostly clear. Low will be in the 
40-45 degree range and most all areas are expected to maintain
a light WNW breeze overnight.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Strong continental high pressure centered over the Plains states 
Friday will move just north of the Southeast region Saturday, then 
offshore by late Sunday. It will bring our area dry conditions with 
mostly clear skies. Temperatures will be within a few degrees of 
normal.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
High pressure will move offshore Sunday night. A coastal trough is 
expected to form Monday while a storm system approaches from the 
west. Models show the system moving through Monday night, then 
perhaps stalling along or just off our coast through Wednesday while 
high pressure prevails inland and to our north. Though, there 
remains uncertainty over the timing, strength, and the track of this 
system.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
As clouds exit the KCHS terminal at 12Z, we now expect VFR 
conditions to prevail through 12Z Friday at both KCHS and KSAV.
The mixed layer deepens this afternoon and forecast soundings 
show large inverted-V type soundings later on, especially at 
KSAV. We continue to forecast wind gusts greater than 20 kt at 
times.

Extended Aviation: VFR through Sunday. There are low probabilities 
of flight restrictions due to an approaching storm system on Monday.

&&

.MARINE...
Lighter offshore flow was tending to diminish sea heights near
shore and we have lowered the SCA in SC waters early this
morning. Offshore flow will back to southwest this afternoon 
becoming shifting west in the wake of a cold front late in the
day GA coast and SC coast early this evening. We may need to 
issue a SCA later today for jetting and surging offshore flow 
in the wake of the cold front tonight over near-shore coastal 
waters. Over the 20-60 NM GA waters, SCA conditions will persist
into Friday morning with elevated seas today and then surging 
offshore flow tonight.

Extended Marine: High pressure will prevail across the region 
through the weekend. Low pressure may move through the Southeast on 
Monday.

Rip Currents: We have a moderate risk for rip currents for today 
as lingering 2-3 ft swell energy which should slowly subside
with time.

&&

.FIRE WEATHER...
A dry cold front will move into Southeast GA this afternoon. Winds
are expected to become gusty with 20-23 kt gusts forecast for at
least 2-3 hours. In addition, RH values will fall to near critical
values. Fuels in this region are the lowest in our forecast area,
but values appear marginal. Per collaboration with SPC Fire Weather,
all of Southeast GA in an elevated potential for fire danger this
afternoon. We have issued a Fire Danger Statement for this region
for anticipated afternoon conditions.

Friday: RH values as low as 25-30 percent and elevated offshore
winds could also cause fire concerns, especially if partners 
report low fuel moisture.

&&

.TIDES/COASTAL FLOODING...
We have issued a Coastal Flood Advisory for the SC/GA coast for
the mid morning high tide cycle. The shallow coastal flooding is
expected to be fairly minor with levels near advisory criteria
due to lingering onshore swell energy which will continue to
diminish throughout the day.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Coastal Flood Advisory until 11 AM EDT this morning for GAZ117-
     119-139-141.
SC...Coastal Flood Advisory until 11 AM EDT this morning for 
     SCZ048>051.
MARINE...Small Craft Advisory until noon EDT Friday for AMZ374.

&&

$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
FIRE WEATHER...
TIDES/COASTAL FLOODING...