369
FXUS62 KCHS 031357
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
957 AM EDT Thu Apr 3 2025

.SYNOPSIS...
Strong Atlantic high pressure will prevail into this weekend,
then a cold front will move through Monday. High pressure will
then rebuild.

&&

.NEAR TERM /THROUGH TONIGHT/...
Morning composite analysis reveals a broad upper level ridge
axis extending from Bermuda across the Florida Peninsula and
southeast region. Large area of surface high pressure sits off
the US Atlantic coast providing S/SE flow across the region as
well as an unseasonably warm and somewhat humid start to the
day. Meanwhile, satellite imagery shows a decent amount of lower
stratocu across the region underneath thicker high cloud cover
leading to partly-mostly cloudy skies.

Pattern changes very little today with upper level ridging
further expanding into the southeast, while surface high
pressure dominates off the coast. Despite anticipated slightly
warmer surface temps and dewpoints, warmer temperatures aloft
will provide a degree of convective capping as well as less
afternoon instability (500-1500 J/Kg MLCAPE) compared to
Wednesday. That said, a few pop-up showers are not completely
out of the question where low-level convergence and instability
is locally maximized (i.e. inland southeast Georgia). But probs
are too low to include explicit pops at this point.

With 850 hPa, 700 hPa, and 500 hPa temperatures in excess of
the 90th or 95th percentile per the ESAT, highs look to reach
the mid and upper 80s inland, with even some places across
interior Georgia touching 90F. Due to the formation of the sea
breeze, coastal temperatures will be down mainly in the 70s.

Tonight: Very little change to the synoptic pattern, other than
the mid-level ridge strengthens even more. The associated
subsidence will negate any chance for rain. Within a southerly
low level flow, and moisture getting stuck beneath the nocturnal
inversion, low stratus will again form. With less wind in the
boundary layer, there might be some chance for fog. But
condensation pressure deficits and FSI aren`t particularly
favorable. So no fog has been included at this time. It`ll be
another warm night with dew points in the 60s, and winds never
fully decoupling in many places. Thus lows will only be able to
drop to the middle and upper 60s.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Upper level ridging along with a surface high pressure to our
east will continue the warm/hot conditions into the weekend.
Afternoon highs for Friday will be in the mid 80s to lower 90s
for inland areas, and upper 70s to mid 80s along the coast,
remaining similarly warm on Saturday as the upper ridge begins
to move eastwards. Sunday may end up marginally cooler as
clouds begin to increase ahead of an approaching cold front.
Each day will see some marginally breezy winds which will be
mixing down the warmer temperatures, along with a daily
afternoon sea-breeze to help cool off. Record high daily
maximums may occur on Saturday, though the current forecast
falls about 3 degrees shy at both Charleston and Savannah
airport. Record high daily minimums look much more likely each
day, with the current forecast within 1-2 degrees Friday-Sunday.

A strong cold front will be moving towards the region overnight into
Monday, with chances for scattered showers and isolated
thunderstorms out ahead of the front starting late Sunday afternoon
and continuing into the overnight hours on Monday. Per the latest
CIPS analogues and CSU MLP`s, severe weather cannot be ruled out
with chances remaining low (~10%), with SPC showing a 15% chance for
far inland southeastern South Carolina and Georgia.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
A strong longwave trough moves towards the region on Monday, pushing
the aforementioned cold front through southeastern SC and GA. This
will continue chances (60-80%) for shower and thunderstorms
throughout the day, while also bringing along with it some cooler
temperatures. Mondays highs will actually be closest to the coast in
the mid 70s, while areas inland will "only" reach up into the lower
70s. The front passes through overnight into Tuesday, bringing
overnight lows into the mid 40s inland to mid 50s along the coast.

Strong cold air advection continues into Tuesday, resulting in
afternoon highs in the upper 60s to lower 70s, with overnight lows
into Wednesday falling into the upper 30s inland to upper 40s along
the coast as a fresh push of cold air arrives with a southward
heading surface high pressure to our north. Wednesdays highs
expected to be in the mid 60s across the region.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
KCHS/KJZI/KSAV: Areas of low stratus/stratocumulus will be at or
near the terminals this morning, leading to MVFR ceilings. A
return to VFR isn`t expected until 16-17Z when mixing heights
finally climb enough. S winds will steadily increase this
morning and become strongest this afternoon during the heating
of the day. Gusts around 20 kt or so will occur, before gusts
diminish by sunset. Flight restrictions will return late
tonight, with the development of the inversion.

Extended Aviation Outlook: Generally quiet aviation conditions
are expected through Sunday, although patchy overnight fog
can`t be ruled out. Monday into Tuesday may bring the return of
MVFR or lower flight rules as chances for scattered showers and
thunderstorms return.

&&

.MARINE...
Today and tonight: Strong Atlantic high pressure covers the
local maritime community, with SE and S winds around 15 kt or
less. The exception will be in Charleston Harbor, where sea
breeze influences could generate some gusts around 20 kt at
times this afternoon. Spectral Density Plots from the nearby
buoys show that the bulk of the wave energy will be in the form
of 9-10 second period swells. The resulting seas reach 3-4 feet
within 20 nm, and up to 5 ft further offshore.

Friday - Saturday: Surface high pressure off to our east, with
generally quiet marine conditions forecasted into the weekend, with
winds around 10 knots. However, with seas averaging 3 to 4 ft waves
in the near-shore waters, coming in every 9-10 seconds, moderate
risk current is expected for Friday. For the Georgia offshore
waters, fairly consistently waves near 4 feet, though those
closer to the 60nm out there will is a slight chance for some 5
footers.

Sunday: The surface pressure gradient begins to rise overnight into
Sunday, remaining elevated throughout the day. Currently have winds
just above small criteria for the Charleston harbor, remaining
below small craft criteria in the near and offshore waters. In
addition, 6 foot waves may begin to move into the offshore
Savannah to Altamaha Sound Georgia waters, possibly reaching 6
foot waves 20nm out in the nearshore Charleston zone. Something
to keep an eye on as we get closer to the weekend. Lastly,
chances for scattered showers and isolated thunderstorms return
overnight into Monday.

Monday: Elevated surface pressure will continue the breezy
conditions, though as the cold front moves into the waters the wind
direction becomes westerly leading to lower wave heights. Small
craft advisories can`t be ruled out this far, with winds currently
below criteria. In addition, scattered showers and isolated
thunderstorms are expected throughout most of the day.

Rip Currents: Onshore winds of 10-15 mph and gusty, plus swells
around 3 feet, equates to a Moderate Risk of Rip Currents at all
beaches today and Friday.

&&

.CLIMATE...
Record High Temperatures:

April 5:
KSAV: 90/1988

April 6:
KSAV: 90/1967


Record High Minimum Temperatures:

April 3:
KCHS: 67/2012
KCXM: 68/2012
KSAV: 68/2012

April 4:
KCHS: 70/1974
KCXM: 69/1974
KSAV: 69/1974

April 5:
KCHS: 65/2017
KCXM: 67/2023
KSAV: 66/1957

April 6:
KCHS: 68/2023 KSAV: 68/2023

&&

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

&&

$$

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