236
FXUS62 KCHS 072226
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
626 PM EDT Mon Apr 7 2025

.SYNOPSIS...
A cold front will impact the region through this evening,
followed by high pressure building into the region through the
middle of the week. Another cold front will move through late
in the week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Main convective line is pressing through the western reaches of
the forecast area...best looking storms of the day. Convective
parameters are still not shabby with a narrow axis of 500-1000
J/Kg...effective bulk shear of 50 knots plus and 2-4 units of
SCP. Given that, tornado watch was extended until 8 pm.

Latest surface obs place the location of an approaching cold front
across central South Carolina southward into central Georgia and the
FL Panhandle. Convection will continue to push eastward across the
forecast area ahead of the front, with showers and storms clearing
the coast by evening. A few strong, perhaps severe, thunderstorms
are possible with the leading edge of convection. Damaging wind
gusts will remain the primary hazard within these storms. Limiting
factors exist, such as poor mid-level lapse rates, keeping a lid on
widespread deep convection. Additionally, forecast soundings at KCHS
have trended toward limited instability and SBCAPE values peaking
around 900 J/kg. lastly, a Tornado Watch remains in effect for the
majority of the southeast GA counties and the southeast SC counties
bordering the Savannah River through 6PM this evening for the
possibility of an isolated tornado in those counties.

Overnight, cold air advection will ramp up behind the front with
850mb temperatures dropping to 5-8C by daybreak Tuesday, with the
NAM showing even colder values around 3-6C. A dry air mass will
filter into the area from the west and cloud coverage will begin to
clear after midnight, especially inland. The pressure gradient will
keep surface winds elevated through midnight, and becoming light a
few hours prior to daybreak Tuesday. With that, low temperatures are
forecast to range from the upper 40s across the interior counties to
the low to mid 50s closer the coast. Upper 50s could be present
along the beaches and Downtown Charleston where in close proximity
to the relatively warm waters.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Southern stream short-wave energy will be advancing through the Deep
South and southeast region on Tuesday helping to push a secondary
surface boundary down through the southeast Tuesday afternoon
into the evening. Forecast is looking to remain dry, although
some lingering cloud cover will persist across the region.
Certainly a cooler and much more comfortable day on tap with
highs dipping back into the lower to middle 70s and surface
dewpoints falling back through the 40s.

Surface high pressure builds into the region in earnest Tuesday
night into Wednesday and dominates through Thursday, with modestly
gusty northeasterly surge developing heading into midweek. This will
deliver reinforcing cooler and drier air with highs Wednesday in the
upper 60s to lower 70s. Temperatures rebound by Thursday back to
around if not slightly above normal (mid to upper 70s). A couple of
cool nights ahead as well with lows spanning the 40s Tuesday and
Wednesday nights (warmer at the beaches), back into the 50s Thursday
night.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Pacific short-wave energy will be diving down through the central
CONUS through midweek and into the eastern/southeastern U.S. at the
end of the week. This is expected to drive another area of low
pressure through the mid Atlantic region and surface cold front
through the local forecast area...currently slated for the daytime
hours on Friday. This will bring our next chance for showers
although for now...keeping PoPs capped at chance/scattered. Recent
guidance depicts somewhat meager instability ahead of the front, a
few to several hundred J/Kg MUCAPE, with the greater amounts across
southeast/southern Georgia. Suppose some TSRA is possible but for
now the forecast will not include thunder.

Behind the front, quiet and rain-free weather returns along with
another push of cooler air spreading into the region for next
weekend. Highs only in the middle 60s to lower 70s on Saturday,
lower to middle 70s on Sunday, before warming back into the 80s on
Monday.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
A solid band of showers and thunderstorms is timed to arrive at
KCHS, KJZI, KSAV between 20-24Z, highlighted with TEMPOs. Some
of these leading thunderstorms could become strong to severe
and produce damaging wind gusts. Behind the leading edge, a
period of stratiform rain or showers with embedded thunderstorms
should continue into the evening, along with a wind shift from
the west dropping to around 10 kt. MOS guidance indicates IFR
to MVFR stratus will spread across the terminals as the rain
ends and remain through the first half of the night. Dry air
should increase across the region a few hours after midnight,
yielding VFR conditions just before daybreak Tuesday.

Extended Aviation Outlook: VFR conditions are expected through
much of the week. Flight restrictions are possible Friday as a
cold front moves through.

&&

.MARINE...
Tonight, the cold front should sweep east of the marine zones this
evening. In the wake of the front, winds will veer from west-
northwest, with gusts below 25 kts. Wave heights should gradually
subside to 3 to 5 ft by late tonight. All Small Craft Advisories
are scheduled to end before daybreak Tuesday.

Tuesday through Saturday: Marine conditions improve on Tuesday,
although another wind surge is expected late Tuesday night into
Wednesday as high pressure builds. Gusts near 25 knots could support
Small Craft Advisories over portions of the waters. In addition, 6
ft seas over the outer Georgia waters could return and persist into
Thursday. The next cold front will move through on Friday, with
conditions currently below advisory levels. No marine concerns are
anticipated for Saturday.

Rip Currents: Monday and Tuesday: Gusty south winds ahead of a cold
front into this evening in combination with 7-8 second swells
supports a High Risk at all beaches. With the winds shifting to the
NE and diminishing on Tuesday post-FROPA, a Low Risk of rips will
return to the forecast.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents until 8 PM EDT this evening for GAZ117-
     119-139-141.
SC...High Risk for Rip Currents until 8 PM EDT this evening for
     SCZ048>051.
MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ330.
     Small Craft Advisory until 6 AM EDT Tuesday for AMZ350-374.
     Small Craft Advisory until 11 PM EDT this evening for AMZ352-
     354.

&&

$$

NEAR TERM...Adam/BRS
SHORT TERM...Adam/ETM
LONG TERM...Adam/ETM
AVIATION...Adam/BRS
MARINE...Adam/BRS