233
FXUS62 KCHS 090601
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
201 AM EDT Fri May 9 2025

.SYNOPSIS...
A front will remain stalled near the area through early next
week. Low pressure will move through Monday and Tuesday,
followed by high pressure.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Early this morning: For now, the forecast area is rain-free.
However, radar imagery shows that some rather robust (for this
time of night) convection is making its way across the SC
Upstate and Midlands. Storm motions are west to east but imagery
already shows a southward moving outflow boundary originating
from this convection. So while the ongoing activity might miss
the forecast area to the north, the outflow boundary is expected
to help initiate new showers and thunderstorms as it pushes to
the south. This new activity will likely impact the forecast
area, with the best chances being across southeast SC and
focused across the Charleston Tri-County region. While upstream
NWS offices are still issuing Severe Thunderstorm Warnings on a
few of these storms, current thinking is that when activity
begins in our forecast area the near storm environment will not
support much (if any) severe threat. There could be some
potential for brief locally heavy rainfall though. This activity
is timed to enter the area around 4-5 am and then continue
through ~8 am before dissipating and exiting to the east. The
other forecast challenge through sunrise will be fog and low
stratus. A few observation sites across southeast SC are already
reporting fog and this will likely continue to be at least a
minor issue. We have added patchy fog to the forecast, but don`t
anticipate significant visibility issues.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
Friday: As an upper-lvl low situates itself over the Gulf
States, an associated cold front will pass through the region in
the evening. SBCAPE values around 1500-2000 J/kg and 0-6km
shear in the 30-35 kt range indicate another day featuring
mainly diurnally driven strong- to-marginally-severe
thunderstorms ahead of the approaching front, with damaging
winds and large hail the primary threats. Additionally, PWAT
values ranging ~1.30-1.50 inches and extremely moist
southwesterly flow being advected into the region locally heavy
rainfall is again possible, with flooding threats mainly limited
to urban, low-lying, and poor drainage areas. Uncertainty
remains with respect to coverage however, as some subtle mid
level ridging could abate coverage somewhat, keeping coverage
more scattered through the afternoon. Expect highs to climb into
the low to mid 80s (with temps. cooler along the beaches).

Friday night: As the cold front passes through the region, any
remaining showers and thunderstorms should push offshore. Cloud
cover will keep temperatures warmer than usual with low to 60s
inland and upper 60s along the coast.

Saturday: This upper-lvl low will remain parked across the Gulf
States and push rich moisture into the Southeast. At the
surface, stationary front will linger nearby and promote showers
and thunderstorms throughout the day. Highest confidence in
severe thunderstorm development will be along the sea breeze in
the afternoon. Locally heavy rainfall is once again expected and
WPC highlighted the entire region under a marginal risk for
excessive rainfall again.

Given the overall pattern, temperatures will be below normal
for this time of year with highs only reaching into the low to
mid 70s with pockets of upper 70s in southeast Georgia.
Northeasterly winds will likely become gusty again in the
afternoon as the sea breeze develops and pushes inland.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
The large closed upper low over central Louisiana will continue
to deepen Sunday and Sunday night before beginning to lift
northeast on Monday. Meanwhile a surface front will remain
stalled along the coast until late Monday afternoon before
lifting north as a warm front. Deep tropical moisture will
stream into the area on Sunday with PWs above 1.75" by the
afternoon. A potent shortwave is expected to move into southeast
GA Sunday afternoon, bringing a wave of convection to the area.
Farther to the north, showers and tstms may be more scattered
in nature, primarily driven by isentropic ascent.

Late Sunday night through Tuesday morning still looks like the
wettest period due to the upper low lifting northeast into the
Tennessee Valley while a deep plume of tropical moisture
overspreads the area. A series of strong shortwaves will move
through the area, likely bringing several rounds of widespread
showers and tstms. Rainfall totals during this time could range
from 2-4". Given the ongoing moderate to severe drought
conditions, any flooding issues will likely be where torrential
rainfall occurs over a short time period.

The upper trough will swing through on Wednesday. Although the
deepest moisture will shift east of the area, scattered showers
are possible on Wednesday given the forcing associated with the
trough.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
KCHS and KJZI: There are a couple of forecast concerns through
the next 6-8 hours. First, web cams and surface observations
indicate that patchy fog is around and could drop into the IFR
range at times. A TEMPO group has been added for 06-10z to
account for these IFR conditions. Second, showers and possibly a
few thunderstorms could drop into the area by around 09-10z from
the north. So there could be brief periods of rainfall and lower
ceilings and visibilities due to showers through about 12-13z.
Then for the afternoon, attention turns to the potential for
thunderstorms. Current hi-res model data suggests that
thunderstorm coverage will be isolated this afternoon and
evening. We have maintained the VCTS beginning at 20z.
Confidence in direct impacts from thunderstorms isn`t
particularly high.

KSAV: VFR conditions should prevail through about sunrise. Then
there are indications that a brief period of IFR stratus will
be possible, generally as early as 10-11z and continuing through
about 13z. We have added a TEMPO group to account for this.
Then for the afternoon, attention turns to the potential for
thunderstorms. Current hi-res model data suggests that
thunderstorm coverage will be isolated this afternoon and
evening. We have maintained the VCTS beginning at 20z.
Confidence in direct impacts from thunderstorms isn`t
particularly high.

Extended Aviation Outlook: MVFR or lower ceiling and/or
visibility possible Sunday through Tuesday as a front remains
stalled nearby and several rounds of showers/tstms move through.

&&

.MARINE...
Through Friday Night: Light to moderate S to SW winds prevail
ahead of a cold front that will move over the waters Friday
night. The front will stall nearby through Saturday with
moderate to breezy N to NE winds north of the front. Gusts could
reach to near 20 kt mainly off the SC coast beginning Saturday,
but SCA conditions are unlikely with seas remaining mainly 2-4
ft.

Saturday through Tuesday: Southeast flow will strengthen over
the waters as low pressure moves up the coast. Some 6 ft seas
could move into outer portions of the offshore GA waters Monday
night and Tuesday.

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...
LONG TERM...
AVIATION...BSH
MARINE...