-- Discussion containing changed information from previous version are highlighted. --
202
FXUS62 KCHS 071115
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
715 AM EDT Tue May 7 2024

.SYNOPSIS...
Atlantic high pressure will remain across the region through
mid week. A cold front will move through the area Friday
bringing cooler conditions heading into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
At daybreak, KCLX detected a cluster of showers and isolated
thunderstorms was located just north of the Santee River, track
to the east. This convection should remain just outside the
forecast area. Temperatures will begin the day in the upper 60s
to around 70.

The axis of a broad mid-level trough will ripple off the coast
during the early daylight hours this morning. H5 heights will
increase through the day as a ridge axis approaches from west,
positioned over the forecast area tonight. The combination of mostly
sunny conditions and rising 1000-850 mb thicknesses should support
high temperatures in the low 90s across SE GA to around 90 across
the SC Lowcountry. Recent runs of the HRRR indicates that a weak sea
breeze will develop late this afternoon, possibly traveling one or
two counties inland before sunset this evening. It is possible that
isolated showers may develop along the sea breeze across portions of
the SC Lowcountry late this afternoon, highlighted with SCHC PoPs.

Tonight: Conditions should remain dry as the H5 ridge axis passes
over the forecast area. Conditions tonight will feature partly
cloudy sky with light WSW winds. Low temperatures should favor
values around 70 degrees.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
Wednesday: The Southeast U.S. will still be positioned on the
western grip of Atlantic high pressure as a series of surface lows
pass across the northern CONUS. Conditions will remain dry with a
mix of clouds and sun. The main focus for the day is on
temperatures, with an unseasonably hot day forecast. Highs will
reach the low 90s, with areas in southeast Georgia reaching the mid
90s. The beaches however will be cooler, topping out in the mid 80s.
Record setting high temperatures are possible Wednesday (see Climate
section below). The good news is that dew points should mix out in
the afternoon, keeping heat index values only a few degrees higher
than the ambient air temperatures. Overnight temps will remain mild
with mins in the upper 60s/low 70s.

Thursday and Friday: A strong cold front will approach the area from
the northeast Thursday bringing a round of showers and thunderstorms
ahead of the front. While the bulk of the day Thursday appears to be
dry, thunderstorms could develop in the early evening and begin to
move into the forecast area. Guidance shows signals of a MCV
developing upstream, which complicates the forecast due to much
dependence on its evolution and propagation. Additionally, the
timing of the severe potential remains a bit uncertain with the NAM
depicting storms to move through late Thursday night, meanwhile the
global models trend toward an earlier evening arrival. Nonetheless,
the environment could be supportive of a notable severe weather
threat with another day of above normal temperatures, resulting in
SBCAPE values in excess of 2,000 J/kg. Deep layer shear looks to be
on the order of 35-45 knots. Temperatures Thursday will reach the
low/mid 90s, with heat indices a few degrees higher, but below the
100 degree mark. Similarly, overnight we expect lows in the upper
60s/low 70s.

Guidance depicts another round of showers and thunderstorms Friday
associated with a shortwave swinging across the northern Gulf states
and the actual passage of the cold front. Timing is rather
uncertain, but activity could be ongoing from the previous night,
with deeper convection developing as early as late morning. Signals
of yet another MCV approaching from the upstream Deep South/Gulf
convection makes this forecast particularly tricky, especially in
terms of the severe threat. Regardless, we will likely see
convection at some point during the day Friday with deep moisture
and forcing in place. Temperatures will be slightly cooler due to
convection and the FROPA, with highs in the mid to upper 80s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
High pressure will gradually build in the wake of the front,
bringing dry, rain-free conditions and cooler temperatures through
the weekend and into early next week.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
12Z TAFs: The terminals should remain VFR through the TAF
period. Terminals will remain dry with southwest winds peaking
during the heat of the afternoon around 10 kts.

Extended Aviation Outlook: Primarily VFR. Chances of showers and
thunderstorms will increase late Thursday through Friday.
-- End Changed Discussion --

&&

.MARINE...
High pressure will remain centered south of the region today and
tonight. Winds should generally remain from the SSW between 10-15
kts through today and tonight. Seas are forecast to range between 2-
4 ft.

Wednesday through Sunday: Atlantic high pressure will maintain hold
over the local marine waters. Southeasterly winds around 10-15 kt
with seas 2-4 ft are forecast through Wednesday night. Winds and
seas will increase/build Thursday into Friday as a cold front
approaches. Small Craft Advisories are possible Thursday/Thursday
night as gusts approach 25 kt, and again Friday night behind the
FROPA. Conditions will improve over the weekend with high pressure
gradually building in from the west. W/SW winds will drop to 10-15
kt and seas will diminish to 3 ft or less.

&&

.TIDES/COASTAL FLOODING...
The upcoming New Moon (May 8) and recent Perigee (May 5) will lead
to elevated astronomical tides over the next few days. Minor
coastal flooding is possible along Charleston and coastal
Colleton Counties, including Downtown Charleston, during the
evening high tides Tuesday through Thursday.

&&

.CLIMATE...
May 7:
KCHS: 93/1977
KSAV: 94/1977

May 8:
KCHS: 93/1986
KSAV: 96/1986

May 9:
KCHS: 95/1963
KSAV: 95/1962

&&

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

&&

$$

NEAR TERM...NED
SHORT TERM...BRM
LONG TERM...BRM
AVIATION...BRM/NED
MARINE...BRM/NED