National Weather Service Raw Text Product

169 
FXUS62 KCHS 251449
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
1049 AM EDT Wed Jun 25 2025

.SYNOPSIS...
Hot and humid conditions are expected to continue with rain
chances increasing today into late week as surface troughing
begins to form near the region and a few upper disturbances
pass through. A few thunderstorms may become strong to severe
on Wednesday. 

&&

.NEAR TERM /THROUGH TONIGHT/...
Late this morning: Overall, a very similar setup to yesterday.
The upper ridge and anticyclone will remain centered across
KY/TN, placing the forecast area within a region of northeast
flow. At the surface, the subtropical high remains the primary
feature but the gradient is quite weak along the coast. The
first order of business concerns hot and humid conditions and
elevated heat index values. Currently, temperatures and
dewpoints are running a bit ahead of where they were 24 hours
ago. Also, low-level thickness off the 12z KCHS RAOB is just a
touch higher than yesterday. So, we expect to at least equal our
temperatures from yesterday with slightly higher dewpoints. This
should yield heat index values of 105-110 degrees for most of
the forecast area, highest across the Charleston Tri-County
region down through Colleton, Beaufort, Jasper, Chatham, and
Bryan counties. The counties inland of this tier might not reach
the explicit Heat Advisory criteria of 108 degrees, but it will
be equally as hot and humid as yesterday. So we have issued a
Heat Advisory for most of southeast GA and southeast SC,
excluding McIntosh, Long, and Liberty counties. 

Second order of business concerns thunderstorm potential this
afternoon. Model guidance continues to favor most of the day
remaining convection-free, with some hints of isolated
initiation occurring late this afternoon. However, severe
weather concerns continue to be concentrated in the evening
hours and there are no changes to that thinking as of yet. 

This Evening: A broad mid-upper lvl low centered off the 
Southeast Coast will slowly nudge eastward with time, forcing 
the large-scale ridge to retreat further inland. Vort energy 
wrapping around the north/northwest periphery of the low could 
play a key role in the development of showers/thunderstorms 
developing across a broad region of sfc troughing over the 
Carolinas (starting across North Carolina), with a bulk of 
global and hires models suggesting activity to congeal/broadly 
organize into a cluster within a modestly sheared environment, 
then tracking south-southwest, primarily just inland to the 
local area near the arriving sea breeze. However, cold pooling 
could easily allow activity to reach inland counties of 
Southeast South Carolina and Southeast Georgia in a severe 
state, and to a lessor degree coastal counties, mainly across 
Southeast Georgia. Locally, environmental conditions are rather 
impressive across inland areas ahead of this activity, with 
SBCAPE around 3500 J/kg, low-lvl lapse rates around 8.5 C/km, 
DCAPE near the 1200-1400 J/kg range and inverted-v soundings 
suggestive of thunderstorms with damaging wind potential should 
they occur locally. There is even some risk for small hail, but 
this will be secondary concern. The primary time-frame for 
severe weather remains between 6PM to 12AM this evening.

After Midnight: Weak shear and loss of diurnal heating will 
eventually take a toll in regards to cold pooling and 
thunderstorm intensity. However, showers and general 
thunderstorms remain in the forecast across southern areas into 
late night. Temps will remain very mild prior to 
shower/thunderstorm activity, but should eventually dip into the
lower 70s inland to mid 70s near the beaches.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
The upper-lvl ridge situated over the Mid-Atlantic that has 
been sitting across the Southeastern CONUS the last couple of 
days will continue to break down throughout Thursday and Friday 
as it moves offshore over the weekend. With this transition, 
expect a more typical summertime pattern to finally setup for 
the next couple of days. Remnant vorticity from an MCS on 
Wednesday combined with a weak upper-lvl low meandering across 
Florida might yield the chance for showers and thunderstorms to 
form in the afternoons on Thursday through Saturday. At the 
surface, an extensive field of moisture will remain over the 
Southeast with PWAT values ranging from 1.50 to 1.75 inches 
throughout the period. This will be more than enough moisture to
spark up some showers and thunderstorms each afternoon as the 
sea breeze pushes inland. In addition, SPC has most of the 
region highlighted by a level 1 out of 5 risk for severe weather
on Thursday with the primary concern being locally damaging 
wind gusts. Overnight lows will remain mild and only dip into 
the low to mid 70s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
This weak upper-lvl low will continue to meander across Florida
before eventually dissipating on Sunday. A more zonal pattern 
will setup over the Southeast and ensembles continue to indicate
daily chances of rain through early next week. Temperatures 
will remain slightly above normal for this time of the year.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will prevail at CHS/JZI/SAV terminals through 
12Z Thursday. However, there is some risk for an afternoon 
shower or thunderstorm impacting the terminals with a sea breeze
shifting inland, followed by another risk for showers and 
thunderstorms during evening hours. At this time, probabilities 
remain too low to include mention of SHRA/TSRA at the terminals 
this afternoon, and the bulk of convection during evening hours 
appears to remain inland to the terminals. Future TAF issuances 
could need to include mention of this activity.

Extended Aviation Outlook: VFR will mainly prevail throughout 
the period, however brief flight restrictions are possible 
within showers and thunderstorms that develop in the afternoon 
and/or evening.

&&

.MARINE...
Today and Tonight: Atlantic high pressure will prevail for a 
bulk of the day and into tonight, favoring conditions that 
remain well below Small Craft Advisory levels through tonight. 
In general, a southwest wind will gradually turn south mid-late 
morning, then peak in the 10- 15 kt range as a sea breeze 
develops and pushes inland. A few showers and thunderstorms 
could arrive to coastal areas late evening and after midnight 
tonight, producing higher wind gusts, seas and some risk for 
severe weather across Georgia waters, but outside this activity,
winds are expected to return to southwest and remain around 10 
kt or less. Seas will generally range around 2 ft.

Thursday through Sunday: As a weak ESE swell continues to mix 
in, seas will remain around 1 to 3 ft. Expect generally 
southerly winds at 5 to 10 kt to prevail throughout the period. 
It could become a bit gusty each afternoon with gusts up to 15 
to 20 kt as the seabreeze pushes inland (gusts strongest across 
the immediate coastline and the Charleston Harbor). Otherwise, 
no marine concerns expected.

Rip Currents: A 1.5 ft, 7-8 second swell will impact the 
beaches along with a 10-15 kt onshore wind today. Given these 
conditions are similar to yesterday with several rip currents 
reported along Tybee Island, GA, a Moderate Risk for rip 
currents is in place along Georgia beaches through this evening.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides will peak around 6.5 ft MLLW at Charleston 
with this evening's high tide cycle. Late afternoon winds will 
only be marginally supportive of increasing tidal departures. 
This evening's high tide will likely peak around 6.8-6.9 ft 
MLLW, falling just short of Coastal Flood Advisory criteria.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ087-088-
     099>101-114>119.
SC...Heat Advisory until 8 PM EDT this evening for SCZ040-042>045-
     047>052.
MARINE...None.

&&

$$

NEAR TERM...BSH/DPB
SHORT TERM...Dennis
LONG TERM...Dennis
AVIATION...Dennis/DPB
MARINE...Dennis/DPB