879
FXUS62 KCHS 100253
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1053 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/...
First Half of Tonight: Latest Radar and satellite data shows
scattered showers and thunderstorms well to the northwest of the
region. However, this convection is moving rapidly east-
southeast and may reach the northern portions of Berkeley
counties within the next 1 to 2 hours. Have brought in slight
chance PoPs a little earlier over that area to account for the
recent radar trends. There were some reports of wind damage with
this system well upstream, but conditions are not quite as
unstable over our northern area. Thus, still feel severe
potential is still low for tonight.

Second Half of Tonight: CAMs guidance continues to show that
the convection, currently over northern GA, will move eastward,
possibly reaching our interior and northern SC counties after
08Z tonight/Monday. Have kept slight chance PoPs in the forecast
to account for this. Again, severe potential seems too low to
mention.

Otherwise, a very mild night, with lows in 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 /03Z MONDAY THROUGH FRIDAY/...
Tonight: VFR conditions will prevail at the terminals. A surface
boundary/weak cold front will push southward through the region
late tonight into early Monday. Still concerned that MVFR CIGS
could develop behind the boundary Monday morning, particularly
at KCHS/KJZI. However, given uncertainty, have kept out mention
of MVFR CIGS, but continue to indicate the potential with
scattered 2-3k ft CIGS, generally after 17Z Monday. Have also
now added Prob30 mention for TSRA in the afternoon. There is a
small chance for some storms to become strong to severe after
17/18Z Monday, especially around KSAV.

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

&&

.MARINE...
Rest of Tonight: A cold front is still expected to reach
northern waters by 06Z, pushing through most of the coastal
waters by daybreak Monday morning. Have introduced slight chance
PoPs for the northern waters for isolated showers/thunderstorms,
with the main impact being the potential for cloud to water
lightning and strong/gusty winds. Outside of any thunderstorms,
southwest winds will likely remain a bit gusty much of the
night, with occasional gusts near 20 kt, especially over the
South Carolina coastal waters, as the front approaches later
tonight. 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.

&&

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

&&

$$

NEAR TERM...Adam/RFM
SHORT TERM...
LONG TERM...
AVIATION...Adam/RFM
MARINE...Adam/RFM