Hanahan, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

644
FXUS62 KCHS 100941
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
541 AM EDT Sun Aug 10 2025

.SYNOPSIS...
A stationary front will linger south of the area through early
this week, while high pressure remains centered well to our
north.

&&

.NEAR TERM /THROUGH TONIGHT/...
Bands of heavy rain continue to move onshore early this morning,
mainly along the lower South Carolina coast. Pops were nudged up
to 100% with these bands. A near term flash flood risk could
setup between Charleston and Savannah through daybreak. Rainfall
rates as high as 2-3 in/hr have been observed around Hilton Head
and could reach as high as 3-4 in/hr at times.

The synoptic pattern has changed little during the past 24
hours. The region remains positioned beneath a large mid-level
weakness with a nearly continuous stream of vorticity crossing
the area as impulses round the periphery of the subtropical
anticyclone centered well offshore. The atmosphere will remain
extremely moist into tonight with PWATs progged to approach
2.5-2.6" at times. MLCAPE will also remain modest through the
period, peaking during the afternoon hours. As impulses move
through, waves/bands of showers/tstms will continue to develop
and push inland throughout the day. This convective pattern will
continue into tonight with most of the activity refocusing back
over the Atlantic and across the coastal counties during the
early morning hours Monday.

The mean steering flow does look a bit stronger than what was
experienced Saturday, but the wind flow will likely support
convective training where clusters of showers/tstms form. Intense
hourly rainfall rates are likely given PWATs will surge above 2.5"
at times. These rates could exceed 3 in/hr at times. This combined
with warm cloud processes, higher mixed-layer instability and wet
ground conditions, will support an elevated potential for scattered
instances of flash flooding through tonight. 10/00z HREF 6-hr
probabilities for >5" are maxing out at about 20-40% in spots
through tonight, suggesting localized amounts in excess of 5" could
occur with a larger, more general 1-3" spread. Given the very wet
antecedent conditions that are in place, a Flood Watch as been
issued for areas roughly along/east of I-95 to address the elevated
risk for scattered urban and flash flooding. This includes both the
Charleston and Savannah Metro Area. Pops will range 80-100% today
with 70-90% tonight, highest at the coast. Highs today will range
from the upper 70s/lower 80s, except lower-mid 80s south of I-16.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Monday: High pressure just offshore of New England will once
again create a wedge of high pressure along the eastern side of
the Appalachian Mountains. Just to the south a stationary front
will remain stalled near the Florida/Georgia border. High
pressure aloft will prevail over Bermuda, with the western
periphery over the local forecast area. The moist and unstable
environment observed over the weekend will persist into Monday.
Models are showing PWATs 2.2-2.4" and CAPE values around 1500
J/kg, supportive of numerous to widespread showers and a few
thunderstorms. The severe thunderstorm threat remains low, with
the main hazard remaining locally heavy rainfall. A Flood Watch
is in effect for counties roughly along and east of I-95 through
6 AM Monday morning. This Flood Watch may need to be extended
into Monday depending on how trends progress. Temperatures will
remain several degrees below normal, with high temperatures in
the low to mid 80s.

Tuesday and Wednesday: The wedge of high pressure at the
surface will begin to break down on Tuesday as high pressure
develops over the Carolinas. Ridging aloft will continue to
build into the region. With high pressure dominating at the
surface and aloft the region will see a pattern shift back
towards a more typical-summertime pattern. Temperatures will
return to near normal, with heat index values approaching triple
digits on Wednesday. Scattered to numerous showers and
thunderstorms will be possible each afternoon, mainly diurnally
driven by the afternoon sea breeze.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
High pressure will dominate at the surface and aloft through
the end of the week and into the weekend. As the high pressure
strengthens temperatures will increase, reaching the low to mid
90s by Thursday. This pattern should yield a typical summer-time
pattern with afternoon thunderstorms and hot and humid
conditions making a return. Heat index values will return to
triple digits, with 100- 105F in the forecast, shy of Heat
Advisory criteria.

&&

.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
10/12Z TAF Discussion:
KCHS/KJZI/KSAV: Waves/bands of showers with embedded tstms will
occasionally impact the terminals through tonight. Timing is
highly uncertain given showers/tstms could pop just about
anywhere at anytime given the very moist conditions that are in
place. Several bands could reach KSAV by mid-morning and
KCHS/KJZI by mid-late morning. Brief instances of IFR vsbys/cigs
could occur with this activity.

Extended Aviation Outlook: Brief flight restrictions will be
possible through the weekend and into early next week with
afternoon showers/thunderstorms.

&&

.MARINE...
Through Tonight: There are no real concerns through tonight.
Easterly winds will prevail with winds around 15 kt. Seas 2-4
ft. Vsbys in showers/tstms could drop below 1 NM at times.

Monday through Friday: High pressure will prevail to the north on
Monday, with high pressure then developing over the local waters
through the remainder of the week. The forecast features winds SE/S
around 10 to 15 knots. Some gusts could approach 20 knots along the
coastline due to the afternoon sea breeze. Seas should average 2 to
3 ft.

&&

.TIDES/COASTAL FLOODING...
The recent full moon (8/9) and upcoming lunar perigee (8/14),
will cause increasing astronomical tide values in the coming
days. In the Charleston Harbor, high tide is expected to peak
around 7 ft MLLW each evening through Monday. Coastal Flood
Advisories could be needed for Charleston and coastal Colleton
counties.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Flood Watch through late tonight for GAZ101-116>119-138>141.
SC...Flood Watch through late tonight for SCZ042>045-047>052.
MARINE...None.

&&

$$