721
FXUS62 KCHS 080517
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
117 AM EDT Tue Jul 8 2025

.SYNOPSIS...
Weak high pressure will extend across the area through the
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: The synoptic pattern has changed little since yesterday
with deep-layered subtropical ridging over the Atlantic
extending west across the Southeast U.S. while a mid-level
weakness persists across the lower Mississippi Valley. This will
maintain a typical summertime southwest flow regime in place
with another resultant sea breeze circulation poised to push
inland this afternoon. The resultant looks to push in a bit
faster compared to yesterday, likely owing to a bit more
southwest flow atop the boundary layer.

Modified forecast soundings suggest convective temperatures may
be about 1-2 degrees lower than Wednesday so convection may
initiate a bit faster. Simulated reflectivity progs off a number
of the CAMS support this trend. 08/01z NBM hourly pops were
utilized with rain chance maxing out in the 30-60% range, highest
across the interior. These values look within reason based on
the latest HREF. The atmosphere has changed little with modified
soundings showing weak shear persisting within a relatively
weak wind environment, especially inland. Convection will
therefore remain fairly slow moving with convective outflow
propagation and other mesoscale boundary interactions likely
dominating localized cell movements. Thermodynamically, modified
soundings continue to show an environment favorable for an
isolated pulse severe tstm or two with a risk for damaging winds
from wet microbursts. Frequent cloud-to-ground lightning and
locally heavy rainfall capable of producing minor flooding in
low-lying and poor drainage areas are also possible.

It will be another warm day with 1000-850 hPa thicknesses and
850 hPa temperatures similar to Tuesday`s values. However, the
combination of a possible earlier start to convection and a bit
more coverage suggests temperatures may not be quite as warm.
Still expect highs to warm into the lower-mid 90s away from the
beaches with possibly a few upper 90s occurring well inland,
especially over far interior Southeast Georgia. Such warm
temperatures will support another round of significant dewpoints
mixing during peak heating. Dewpoints look to mix out in the
upper 60s/near 70 well inland while holding in the lower 70s
east of I-95. Another round of moisture pooling near the
near/behind the sea breeze will help surge dewpoints into the
mid-upper 70s with a few 80 degree readings possible along the
Charleston County coast. Heat indices will peak in the 102-105
range for most areas with 105-108 occurring across parts of the
Charleston Tri-County area near the sea breeze. This is
generally below Heat Advisory criteria (108-112 for at least 2
hrs), although a few spots along and just east of the US-17
corridor in Charleston County up into the Francis Marion
National Forest could briefly exceed 108, which includes
Downtown Charleston. For the Charleston Tri-County area,
neighborhood probabilities for heat indices exceeding 108 are
10-30% depending on location.

Tonight: Convection will linger across the interior through
about mid-evening before dissipating with the loss of
insolation. Lows will range from the mid 70s well inland to the
mid-upper 70s across the coastal counties with lower 80s at the
beaches and Downtown Charleston.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
The surface pattern will feature high pressure offshore with a
weak trough of low pressure across the Appalachians. Aloft,
subtle ridging will erode Wednesday as a shortwave begins its
track across the Tennessee Valley. A sea breeze pattern will
dominate through the period, although some upper forcing could
spread in from the north. Scattered to possibly numerous showers
and thunderstorms are possible each day through Friday, mainly
in the afternoon and evening when instability is maximized.
There is no shortage in moisture content noted via PWATs above
2.2" and model soundings showing close to saturated upper
levels. This could lead to heavy downpours within storms.
Additionally, little steering flow, especially Wednesday, could
result in quick bouts of rainfall and minor/nuisance flooding.
High temperatures will reach the upper 80s at the beaches and
low 90s elsewhere both Wednesday and Thursday. Friday could see
highs about 1-2 degrees warmer, approaching the mid 90s.
Overnight lows both Wednesday and Thursday night will remain in
the low/mid 70s away from the coast, and upper 70s at the
beaches.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
The slightly eroded upper ridge to our east will build back
over the Southeast through the weekend and into early next week.
Otherwise, little change expected in the overall synoptic
pattern and the forecast. Typical diurnal convection will
continue with scattered showers and thunderstorms forming each
day in the afternoon/evening. Highs will be above normal,
reaching the mid 90s most places over the weekend.

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
08/06z TAF Discussion:
KCHS/KSAV/KJZI: VFR will prevail for much of the period.
Scattered showers/tstms are expected to develop near/ahead of
the afternoon sea breeze. Some of this may brush KCHS and KSAV
before focusing west of the terminals by mid-late afternoon.
Impact probabilities are too low to justify a mention at this
time, but the need for TSRA will be reevaluated with the 12z TAF
cycle.

Extended Aviation Outlook: Brief ceiling/vsby restrictions
possible due to scattered showers and thunderstorms.

&&

.MARINE...
Through Tonight: Southwest winds will back to the south this
afternoon with the afternoon sea breeze with southerly winds
holding through the night. Speeds will generally range from
10-15 kt, but will be closer to 15 kt with gusts to 20 kt near
the land/sea interface and Charleston Harbor near and behind the
sea breeze. Seas will average 2-3 ft.

Wednesday through Sunday: Relatively benign conditions are
forecast and as a result there are no marine concerns during the
period. South to southwest flow will persist with high pressure
to the east. Wind speeds will be 15 kt or less and seas will
average 2-3 ft, with some 4 foot seas moving in at times
Thursday and Friday.

&&

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

&&

$$