861
FXUS62 KCHS 092038
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
438 PM EDT Sun Jun 9 2024

.SYNOPSIS...
A cold front is expected to sweep across the forecast area on
Monday, followed by an unsettled pattern mid to late week.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Stacked low pressure will slowly advance through New England
with suppressed heights and stronger westerly mid level flow
pressing down into the Carolinas. Aforementioned surface
boundary will also sag down into and through the region during
the overnight hours into early Monday morning. There are some
showers and thunderstorms ahead of the boundary slipping into
Tennessee although that activity may largely bypass our area to
the north.

Bigger question remains with whether or not we see renewed
convection in the lower Mississippi River Valley later this
afternoon into this evening...as most high resolution guidance
solutions have shown throughout the day. Associated convectively
induced wave could press eastward along the boundary and
support showers and thunderstorms spreading through northern/
central Georgia and across South Carolina...largely during the
overnight hours. 12Z/18Z HRRR solutions continue to suggest that
most of the activity just skirts the northern part of the CWA
late overnight into Monday morning. We plan to more or less
maintain our current forecast with isolated to scattered pops
overnight. Given the the late arrival of convection and poor
environment, no severe weather is expected at this time. Low
temperatures should range from the low 70s inland to the mid to
upper 70s along the coast.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Monday: The mid-levels will consist of a positively tilted trough
amplifying over the East Coast as time progresses. Additionally, a
weak impulse is expected to pass over our area towards the evening.
There also may be a jet streak to our north overnight. At the
surface, a cold front located approximately over our northernmost
counties at daybreak will slowly shift southeast during the day,
likely becoming located offshore to our southeast by the afternoon,
and then transitioning to a stationary front during the evening and
overnight. There will be a plume of moisture with the front, with
PWATs peaking around 2" during the afternoon. The models even hint
at higher values in some locations. Either way, these values are
above the 90% mark for CHS per SPC sounding climatology. While NAEFS
PWATs seem a little lower, there are signs that if the values were
similar, then this would be nearly 2 standard deviations above
normal. Lift around the vicinity of the front and the afternoon sea
breeze will combine with the moisture to generate convection. The
highest POPs will initially be across our coastal and inland GA
counties, then spread north into our SC counties during the later
afternoon and evening. Convection should decrease a bit towards
midnight, remaining closer to the coast afterwards. The highest
instability is along our GA coast, where MLCAPEs could reach 2,000
J/kg. There is a decent amount of shear there, with DCAPEs exceeding
1,000 J/kg. So a few marginally severe thunderstorms with damaging
winds cannot be ruled out in the afternoon and evening. SPC has most
of our area under a Marginal Risk and this seems reasonable. While
severe is the main concern, rainfall potential is also up there.
Depending on how the front, sea breeze, and boundaries interact,
there could be training and backbuilding storms. Heavy rainfall is
possible, with some spots getting 1-2", locally higher. This will
mainly be along our coast, especially our GA coast. Temperatures
will range from the mid/upper 80s across our northernmost locations,
to the mid 90s closer to the Altamaha. Lows will range from the mid
60s far inland to the lower 70s near the coast.

Tuesday: The positively tilted trough prevails over the East Coast
during the day, shifting offshore overnight. The surface stationary
front will meander just off our coast during the day and into the
night. Additionally, High pressure will be centered to our northwest
and gradually building into our region. Even though the highest
PWATs will remain offshore, values should still generally range
between 1.25-1.75" during the day. It appears there will be enough
moisture and instability to generate scattered convection along the
sea breeze. Though, more drier air later in the day could somewhat
limit this potential. The convection will diminish during the
evening, with it being dry just about everywhere overnight. Highs
will peak in the upper 80s to lower 90s. Lows will range from the
mid 60s far inland to the lower 70s near the coast.

Wednesday: Weak mid-level troughing will approach from the Lower MS
Valley. At the surface, weak High pressure will remain to our north
while a stationary front will be located just to our south and
southeast. There appears to be enough moisture across our area to
support diurnal isolated to scattered convection across our GA
counties, while our SC counties should have little, if any
convection. Temperatures should remain slightly above normal.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The general pattern remains unsettled and uncertain. A large,
unorganized area of Low pressure could potentially develop somewhere
in the Gulf of Mexico. Most models indicate that at least some of
the deep layer/tropical moisture associated with this feature could
spread northeastward toward our region, especially by late in the
week. This would support diurnal convection, with the potential for
locally heavy rainfall. Temperatures should be near to slightly
below normal.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Tonight: VFR conditions will prevail at the terminals this
afternoon and tonight. Surface boundary will slip down through
the region late overnight into Monday. MVFR cloud cover could
develop at the terminal sites behind the boundary Monday
morning particularly at KCHS/KJZI, although we will indicate
just SCT lower cloud layers for now.

Otherwise, west-southwesterly winds this afternoon into tonight
will veer northerly late overnight into Monday behind the
boundary.

Extended Aviation Outlook: Convection will bring the chance for
periodic flight restrictions later Monday through Tuesday, and then
again Thursday and Friday.

&&

.MARINE...
Tonight, a cold front is forecast to reach the coast by 6Z,
pushing across most of the coastal waters by daybreak Monday
morning. As the front approaches, SW winds may surge with gusts
around 20 kts. Winds are time to veer from the northwest during
the pre-dawn hours. Seas are forecast to build to 2-4 ft during
the wind surge ahead of the cold front.

Extended Marine: A cold front will slowly move through our waters on
Monday, then become a stationary front to our southeast Monday
night, possibly meandering through the middle to end of the week.
Despite potentially unsettled weather, conditions are expected to
remain below Small Craft Advisory criteria.

&&

.CLIMATE...
Record High Temperatures
June 9:
KCHS: 99/1986

&&

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

&&

$$

NEAR TERM...Adam
AVIATION...Adam
MARINE...Adam