Charleston, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

784
FXUS62 KCHS 191109
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
709 AM EDT Sat Jul 19 2025

.SYNOPSIS...
High pressure will prevail in the Atlantic through early next
week, with surface troughing inland. A front could stall nearby
towards the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early morning satellite water vapor indicated a deep ridge across
the Southeast U.S. Near term guidance shows that the center of the
H5 596 dm ridge will remain over northern FL through this afternoon.
At the sfc, broad high pressure is forecast to remain across the
western Atlantic to the Gulf, inland a lee side trough will develop
across the western Carolinas by this afternoon. This pattern should
support light WSW winds across the forecast area this morning. By
this afternoon, high resolution guidance times a slow-moving sea
breeze will begin to slide inland late this afternoon. The
combination of late sea breeze timing, very warm llvl thicknesses,
and strong insolation should result in high temperatures generally
in the upper 90s. Forecast soundings indicate that mixing heights
across inland GA/SC will peak around 6 kft this afternoon. The deep
mixing should result in dewpoints to lower to around 70 degrees
across the far inland zones during the heat of the afternoon. Closer
to the coast, moisture pooling along the sea breeze should keep sfc
dewpoints in the mid to upper 70s. The combination of the hot
temperatures and dewpoints in the mid to upper 70s should yield heat
index values between 108 to 110 along and east of the I-95 corridor.
In fact, some pockets across the coastal counties may see heat index
values reach 113 degrees. A Heat Advisory will be in effect for all
counties along and east of I-95 through early this evening. Latest
HREF indicates that shower and thunderstorm activity will remain
along the immediate coast this afternoon, coverage should support a
thin area of isolated convection. The afternoon convection should
provide little to no relief from the afternoon heat.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
The mid-levels will consist of a 595 dam ridge over the Southeast
U.S. on Sunday. It`ll shift westward as time progresses, becoming
located over the Lower MS Valley by Sunday. This will lead to
gradually lowering heights over our area. At the surface, a typical
summertime pattern will be in place with High pressure prevailing in
the Atlantic, with surface troughing inland. A cold front could
approach from the north late Monday, possibly stalling over or just
to our north on Tuesday. Deep moisture will be in place throughout
the short term, with PWATs upwards of 2".

The main forecast highlight continues to be the heat. High
temperatures will be in the mid to upper 90s Sunday and Monday, with
some spots possibly reaching triple digits. Combined with dew points
in the low to mid 70s, heat indices should peak in the 105-110
degree range, with some spots higher along the immediate coast where
there is more moisture pooling. A Heat Advisory will likely be
needed Sunday and Monday for most of the area. High temperatures
trend lower on Tuesday (ranging from around 90 degrees to the middle
90s), so it`s more uncertain if an advisory will be needed, as heat
indices may barely reach 108 degrees in some spots.

The convective potential varies each day. The NBM keeps most of our
area dry on Sunday. Monday it raises POPs into the 30-50% range.
Then, by Tuesday it drastically raises POPs into the categorical
range. We`ll see how well that pans out with future forecasts. But
given the instability in place, a strong to marginally severe
thunderstorm cannot be ruled out any day, with damaging winds being
the main concern. Locally heavy rainfall is also a concern,
especially if there is slow storm motion and/or back-building.

Any convection should wane with nightfall. Overnight lows will
remain mild, in the mid to upper 70s, warmest along the beaches.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Models are in good agreement keeping a mid-level ridge in place
through Thursday, then breaking it down on Friday. At the surface, a
weak stationary front is expected to sag into our region midweek,
then dissipate towards the end of the week. While the forcing
mechanism will be weak, expect a wetter pattern through the end of
the week, with diurnal convection forecasted each afternoon.
Temperatures will remain near normal.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
12Z TAFs: VFR. At the sfc, broad high pressure is forecast to
remain across the western Atlantic to the Gulf, inland a lee
side trough will develop across the western Carolinas by this
afternoon. This pattern should support light WSW winds across
the terminals this morning. By this afternoon, high resolution
guidance times a slow-moving sea breeze will begin to slide
inland late this afternoon. The TAFs will include change groups
to highlight the wind shift timing. Latest HREF indicates that
shower and thunderstorm activity will remain along the immediate
coast this afternoon, coverage should support a thin area of
isolated convection. Coverage appears too low to mention in the
TAFs at this time.

Extended Aviation Outlook: Mainly VFR through Sunday. There could be
brief flight restrictions due to afternoon/evening showers and
thunderstorms starting Monday.

&&

.MARINE...
Today and tonight, at the sfc, broad high pressure is forecast to
remain across the western Atlantic to the Gulf, inland a lee side
trough will develop across the western Carolinas by this afternoon.
This pattern should support light WSW winds across the terminals
this morning. By this afternoon, high resolution guidance times a
slow-moving sea breeze will begin to slide inland late this
afternoon. This pattern will generally support SW winds 5 to 10 kt,
becoming S 10 to 15 kt late. Seas should favor values between 2 to 3
ft today, increasing to 2 to 4 ft tonight.

Extended Marine: High pressure will prevail in the Atlantic through
Monday, while surface troughing is inland. This will yield a typical
summertime wind pattern. During the day, expect backing winds with
the formation of the afternoon sea breeze. The highest gusts will be
along the land/sea interface and across Charleston Harbor (with its
passage). During the night, expect veering of the winds as a
nocturnal jet tries to set up close to shore. Winds will shift to
the NE Monday night as a front approaches and stalls nearby,
possibly remaining in place through the middle of next week. The
typical summertime wind pattern may return towards the end of next
week. Seas should average 2-3 ft for most of the extended. Though,
there are indications that seas could approach 5-6 ft towards the
middle of next week. This seems a bit overdone, so we clipped them
lower than what the pure model data was showing for now.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for GAZ101-116>119-138>141.
SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for SCZ043>045-047>052.
MARINE...None.

&&

$$

NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...NED