Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 171146
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
746 AM EDT Tue Oct 17 2017

.SYNOPSIS...
Strong high pressure will build over the area through next
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: The main upper trough will continue to dampen and shift
off the east coast as the channeled vorticity max associated
with it drags through. The surface pattern will hardly change
through the day as a 1025-1030 mb high over the central
Appalachians shifts towards the Mid Atlantic region. This will
result in persistent cool northeast flow producing a day where
temperatures will actually be below normal for a change. Highs
are forecast to be in the 69-72 degree range across southeast
South Carolina, and in the low 70s across southeast Georgia.
Such values would roughly 6 degrees below normal. The tight
pressure gradient associated with the high will continue to
support breezy northeast winds through the afternoon. Wind gusts
should top out around 20 mph in most areas, with 25-30 mph
gusts possible at the beaches. We will see a good amount of mid
and upper level clouds in the morning, but this should decrease
through the latter part of the day.

Lake Winds: The Lake Wind Advisory for Lake Moultrie will
continue through 8 am due to gusts to 25 knots across the lake.

Tonight: The synoptic setup remains the same as the center of
the surface high sits to the north just in the lee of the
central Appalachians. The forecast is dry and the main story
will be the cool temperatures. The persistent elevated northeast
flow will prevent ideal radiational cooling conditions so
temperatures won`t be as low as they could be under different
circumstance. Forecast lows are in the mid 40s well inland,
ranging to the low to mid 50s closer to the coast.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Strong, dry high pressure will expand southeast across the area
during the period. Weak moisture convergence over the coastal
waters may support isolated showers Wednesday into Thursday. A
building upper ridge Thursday into Friday will yield warming
temperatures and diminishing rain chances over the waters.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A deep layered ridge will maintain mostly dry weather and
seasonable temperatures through Saturday. A southern stream
shortwave will bring increasing moisture and a potential Gulf
surface low into the area early next week. This would be our
next chance for measurable rainfall, potentially Sunday but more
likely Monday into Tuesday.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Gusty northeast winds will persist through the day. Gusts will
mainly be in the 20-25 knot range. Mid/high level clouds will
gradually thin through the day.

Extended Aviation Outlook: VFR.

&&

.MARINE...
Today through Tonight: Strong northeast flow across the local
waters will persist nearly unchanged today through tonight. the
best cold air advection will take place this morning, and
thermal gradients will diminish a bit through tonight. Solid
Small Craft Advisory conditions will remain through the entire
period. Winds today will generally be 20-25 knots with gusts to
30 knots, with modest weakening overnight. The advisory for the
Charleston Harbor will run through this evening, and winds will
diminish overnight dropping off to something more like a solid
15 knots. Seas of 4-7 feet are expected out to 20 nm with 7-10
feet beyond.

A persistent NE gradient will continue into Wednesday night,
gradually weakening late week into the weekend as the surface
high builds overhead. Small Craft Advisory conditions expected
to exist over the nearshore waters into Thursday afternoon,
mainly due to seas, with the offshore GA waters seeing SCA
conditions extend into Saturday.

&&

.TIDES/COASTAL FLOODING...
Strong/persistent northeast winds will push higher water levels
to the coast this week. Minor coastal flooding will be possible
around the times of high tide continuing into Thursday or
Friday. Coastal Flood Advisories will likely be needed.

&&

.EQUIPMENT...
Hourly observations and daily climate data from the weather
sensor along Riley Waterfront Park (KCXM) in Downtown Charleston
will not be available until further notice. The cause of the
senor outage is possibly linked to a bad transmitter at the
site. Technicians continue to evaluate the system for a possible
resolution.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Rip Current Risk through this evening for GAZ117-119-139-
     141.
SC...None.
MARINE...Small Craft Advisory until 5 PM EDT Thursday for AMZ350-352-
     354.
     Small Craft Advisory until 8 PM EDT Friday for AMZ374.
     Small Craft Advisory until 8 PM EDT this evening for AMZ330.

&&

$$

NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH/JRL
MARINE...BSH/JRL
TIDES/COASTAL FLOODING...
EQUIPMENT...


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