Hanahan, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

935
FXUS62 KCHS 211904
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
304 PM EDT Wed May 21 2025

.SYNOPSIS...
A cold front will push offshore this evening and be followed by
high pressure through the weekend. A warm front will lift north
through the area Sunday and Monday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Rest of the afternoon: As the cold front begins to move into our
east-central Georgia and west-central South Carolina counties, the
surface pressure gradient will remain elevated which will continue
our breezy southwesterly winds. There is a plume of 850mb moisture
well out ahead of the surface front, and is draped from the southern
CSRA across southern Georgia into northwestern Florida. This will
keep convection chances limited to our southeastern Georgia
counties, mostly likely limited to areas along/south of Long and
McIntosh counties. If storms were able to form, 1500-2000 J/kg of
CAPE along with 30 to 40 knots of bulk shear leads to a limited
threat for large hail (1"+), though given the heat it`d be difficult
to get that down to the surface. The greater threat comes from
strong winds due to 1000-1500 J/kg of DCAPE, which would lead to
storms being able to produce strong wind gusts to 60 mph. However,
vast majority of guidance keeps the region dry for the rest of the
day, even along the cold front as it moves through due to
substantial dry air aloft.

Tonight: As the front slips through, winds will be decreasing as a
more stable airmass moves in behind the front, though we`ll remain
sustained around 5 to 10 mph given the elevated surface pressure
gradient behind the front. Much cooler air than we have been seeing
moves in overnight, dropping temperatures down into the  lower to
mid 60s inland, and mid 60s to upper 60s along the coast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
Cyclonic flow aloft will persist through Friday until the base of
the East Coast Longwave trough shifts offshore. Heights will begin
to slowly rise through the weekend. A weak, reinforcing cold
front will clear the coast Thursday night with high pressure
building in from the northwest and eventually north. The front will
pass through dry with little to no meaningful moisture return noted
ahead of it. Dry conditions will prevail through Saturday. Highs
will warm into the upper 80s/near 90 Thursday with lower-mid 80s
Friday and Saturday with a few upper 80s possible near the Altamaha
River. Lows Friday morning will drop to around 60 inland to the
lower 70s at the beaches and Downtown Charleston with lower-mid 50s
inland to the upper 60s at the beaches and Downtown Charleston for
Saturday morning.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A warm front will approach from the south Sunday and meander to the
north of the area Monday as a storm system organizes over the
middle/southern Mississippi Valley. There are uncertainties on
exactly where the warm front will become quasi-stationary with
signals that a wedge may try and sharpen over parts of the
Carolinas. Rain chances will begin to increase Sunday into early
next week as the warm front meanders near the area and the
atmosphere becomes increasingly more conducive for a more summer-
like convective pattern.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
21.18Z: VFR expected for the vast majority of the region, with
scattered showers and thunderstorms possible for areas along and
south of the Altamaha River adjacent to Long and McIntosh counties
into the early evening hours. Otherwise, southwest winds 15 to 20
knots with gusts to 25 knots will continue out ahead of an
approaching cold front, with winds decreasing into the evening and
overnight hours as they shift to become out of the northwest. Likely
won`t fully decouple from the boundary layer, which will keep winds
sustained around 5 knots.

Extended Aviation Outlook: There are no concerns with a >50%
confidence level.

&&

.MARINE...
Rest of today and tonight: Small Craft Advisory in effect for
near- shore southeastern South Carolina waters. Southwest winds
15 to 20 knots with gusts to 25 knots will continue out ahead of
an approaching cold front along the near-shore South Carolina
waters, a touch weaker for the near and off shore Georgia
waters. Expect a brief lull in wind activity as the front pushes
through this evening, with northwest winds picking up later
this evening into the overnight period. Strongest winds are
again expected along the near- shore South Carolina waters, with
speeds of 15 to 20 knots with gusts to 30 knots. Southeast
Georgia near and offshore waters will likely also be in the 15
to 20 knot range, with gusts to 25 knots...currently expected to
remain just shy of Small Craft criteria. However, if confidence
increases in the strength of the winds overnight, both near and
offshore southeastern Georgia waters may need to be added to
the Small Craft Advisory.

Thursday: Offshore winds in the wake of a cold front will quickly
veer to the southwest during the day. Another gusty day is expected
over the waters with winds potentially getting as high as 15-20 kt
in both the Charleston Harbor and the South Santee-Edisto Beach
nearshore waters. Gusts to 25 kt will be possible. A Small Craft
Advisory may be needed if those gusts to 25 kt are expected to
become more frequent. Winds will turn offshore late as a secondary
cold front pushes offshore. Seas will average 1-3 ft.

Friday through Monday: Offshore winds will prevail Friday with
northerly winds developing Friday night into Saturday as high
pressure noses in from the north. Southerly winds quickly return
Sunday into Monday as a warm front lifts to the north. Speeds will
generally remain 15 kt or less through the period, but could surge
as high as 15-20 kt Sunday night as a little nocturnal jetting takes
shape. Seas will generally average 4 ft or less through the period,
but get close to 5 ft by Monday, especially in the South Santee-
Edisto Beach nearshore leg and the Georgia offshore leg.

&&

.CLIMATE...
Record High Minimum Temperatures:

May 21:
KCHS: 74/2022
KCXM: 78/1998
KSAV: 74/2017

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for AMZ330-350-
     352.

&&

$$

NEAR TERM...APT
SHORT TERM...0
LONG TERM...0
AVIATION...APT/0
MARINE...APT/0