006
FXUS62 KCHS 301031
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
631 AM EDT Mon Jun 30 2025

.SYNOPSIS...
High pressure will extend across the region early this week. A
cold front will then approach the area around the middle of the
week, possibly stalling near the coast through late week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today and Tonight: An upper level low will continue to
retrograde west with mid and upper level dry air on the
northwest flank. This mid-level dry air can be clearly seen on
channel 9 of the water vapor this morning and will make slow
progress to the west this morning. At the surface, high pressure
near Bermuda will remain in control with a sea breeze slowly
pushing inland. The best surface convergence actually looks to
be in GA this afternoon due to the inland moving sea breeze and
westerly flow across GA ahead of an approaching mid-level wave.
Have raised PoPs to likely across GA and lowered PoPs towards
Charleston due to the dry air (30% - 40% RH in the 500 to 300 mb
layer). Expect high temperatures in the lower 90s with heat
index values topping out in the 100 to 105 degree range.
Convection will then come to an end late this evening. Expect
low Monday night/ Tuesday morning in the low to mid 70s.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday: The local forecast area will be located within an area of
lower pressure in the upper levels as high pressure resides to the
east over the western Atlantic and to the west over ArkLaTex.
Additionally to the north an upper level trough will be positioned
over the Great Lakes, with the southern periphery over the
southeastern states. At the surface a cold front will begin
approaching from the west, associated with the upper level trough,
while the center of high pressure lingers over the western Atlantic.
Across the local forecast area this surface set up will create a
somewhat pinched pressure gradient, resulting in wind gusts around
25 mph along the Charleston County coastline in the afternoon. Ahead
of the approaching cold front there will be plentiful moisture, with
PWAT values around 1.8-1.9" and CAPE values around 1500-1700 J/kg.
Numerous to widespread showers and thunderstorms will be possible in
the afternoon, with the greatest chances across southeastern GA
where better moisture and instability values will reside. Given the
increase in precipitation coverage high temperatures will only reach
into the upper 80s to around 90.

Wednesday: The upper level trough will shift eastward slightly, with
the southern periphery of the trough reaching the Panhandle of
Florida. The aforementioned cold front will continue its approach
towards the forecast area, likely stalling in the vicinity of the
southeastern coastline between Wednesday and Thursday. Wednesday
will likely see the greatest coverage of showers and thunderstorms
given the proximity of the cold front. PWAT values could approach
2.2 inches, which would be near the daily maximum PWAT value
according to SPC Climatology. CAPE values are forecast to reach
upwards of 2000 J/kg, providing ample instability for convection.
Similar to Tuesday, the increased coverage of precipitation will
limit high temperatures to the upper 80s to around 90.

Thursday: The upper level trough will remain positioned over the
East Coast, while the cold front at the surface lingers in the
vicinity of the southeastern coastline. There is a possibility that
a low pressure could develop along the stalled front, however
confidence in this is low at this juncture. Another afternoon of
scattered to numerous showers and thunderstorms is in the forecast,
with possibly greater coverage if a low pressure is able to develop.
Temperatures will reach into the low to mid 90s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
The upper level trough will shift off the New England coastline on
Saturday, with high pressure centered over ArkLaTex building into
the southeastern states aloft. At the surface high pressure will
build into the region from the north as the weak front slowly pushes
further into the western Atlantic. A low pressure could develop
along the stalled front late this week/this weekend, however
confidence in this is low at this juncture. Precipitation chances
return to near climatology through the weekend, generally around 30%
in the afternoon. Chances could be higher if a low pressure is able
to develop. High and low temperatures will remain near normal
through the period.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
30.12Z TAF Discussion:
An upper level low is slowly retrograding west with dry mid
level air on its northwest flank. During the afternoon today,
the mid and upper level dry air will be over the TriCounty with
southerly winds at the surface. Meanwhile, towards KSAV a sea
breeze will begin to push inland with moisture pooling out ahead
of the upper level low. This will make for an unusual/ non-
climatological favored setup with the highest chance of
convection being across inland/ coastal GA and lower chances
towards Charleston County. Convection will then come to an end
late this evening.


Extended Aviation Outlook: Brief flight restrictions are
possible Tuesday afternoon with convection. Wednesday and
Thursday, more widespread coverage of showers and thunderstorms
are forecast as a cold front approaches from the northwest. This
could provide more frequent periods of ceiling and visibility
restrictions.

&&

.MARINE...
The marine zones will remain between high pressure centered
over the western Atlantic and broad trough across the middle
Carolinas and GA. This pattern should yield southerly winds
generally between 10-15 kts. Seas are forecast to range between
2 to 3 ft.

Tuesday through Saturday: On Tuesday the local marine waters will be
within a pinched gradient with a cold front approaching from the
west and high pressure to the east. This pinched gradient could
produce a period of 25 knot wind gusts in the afternoon hours across
the Charleston County nearshore waters. A Small Craft Advisory may
be required. Otherwise, conditions through the period are forecast
to remain below Small Craft Advisory criteria with winds generally
10 to 15 knots and seas averaging 2 to 4 ft.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$

NEAR TERM...Haines
SHORT TERM...CPM
LONG TERM...CPM
AVIATION...CPM/Haines
MARINE...CPM/Haines