679
FXUS62 KCHS 241131
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
731 AM EDT Fri Jul 24 2026

.WHAT HAS CHANGED...
The aviation section updated for the 12Z TAFs.

&&

.KEY MESSAGES...
- 1) A Flood Watch is in effect for the Charleston Quad-County
  in the SC Lowcountry. Locally heavy rainfall will be possible
  today and Saturday.

&&

.DISCUSSION...
KEY MESSAGE 1: A Flood Watch is in effect for the Charleston
Quad-County in the SC Lowcountry. Locally heavy rainfall will
be possible today and Saturday.

Today: A slow moving front will drift southward today into
southeastern SC. The afternoon sea breeze is forecast to begin
pushing inland around noontime, interacting with the front
beginning in the early afternoon. The interaction of the slow
moving (nearly stalled) front and the sea breeze will lead to a
threat of heavy rainfall this afternoon across the SC Lowcountry
and Southeastern GA. A Flood Watch has been issued for the
Charleston Quad-County, where the greatest risk of heavy
rainfall resides. Forecast soundings show long, skinny CAPE
profiles with CAPE values around 1500-2000 J/kg and Corfidi
vectors are forecast to only be around 5 to 10 knots. These
parameters support heavy rainfall across the watch area.
Additionally, PWAT values are forecast to reach upwards of 2.4",
which would exceed the daily max according to SPC Climatology.
The 00Z HREF probabilities also support the heavy rainfall
threat, with a 50% contour of the 3-hr QPF exceeding 3" across
the watch area. Locations within the watch will likely see 3-5
inches, with 1-3 inches elsewhere. With the convective nature of
the precipitation it cannot be ruled out that some locations
could see slightly higher amounts. The main timeframe for these
heavy downpours is 3-9 PM.

Saturday: Our aforementioned front will have moved well into the area
by the morning hours Saturday with a large slug of moisture
streaming up from the Gulf coast. The main trough axis looks to have
moved slightly eastward and will continue to slowly lift east-
northeast throughout the day as a series of subtle shortwaves moves
through the broader west-southwesterly flow a loft. Saturday is
looking very similar to Friday; however, with the slight shift in
the trough axis the best forcing will be more focused along the
coastline. Showers and storms will likely already be ongoing early in
the morning mainly north of I-26 but the real show likely arrives
during the afternoon. Much like Friday storms will likely quickly
develop during the afternoon along the seabreeze. The only main
difference is with the main trough axis closer to the coast, storms
may be more confined along the immediate coastline rather than
inland. Given this uncertainty of location being over maybe more
marshy sandy soils that can handle more water than say inland or
urban areas, we have withheld any flash flood watch for this time.
However, PWATS in place will range in the 2.2 to 2.4 inch range
which would rival the daily record PWAT at CHS and right at our
average max PWAT for this time of year. In-short this airmass will
be rather juicy and capable of rather intense rainfall rates likely
in the 2 to 3 inches per hour range. IF, storms are able to develop
more closer to the Charleston metro or further inland on Saturday
then flash flooding concerns would quickly escalate. On top of this,
we will have to see how Friday plays out and how much rain falls
then which could further increase the flash flood potential Saturday
as soils become saturated. Depending on trends, we will likely make
a decision on a continuation of the Flash Flood watch by later today
or tonight. The area of greatest concerns is certainly centered
around the quad-county area and Charleston Metro.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
12Z TAFs: Conditions across the terminals will remain dry with
light SW winds through early this morning. Scattered to
numerous showers and thunderstorms will likely develop along the
sea breeze across KCHS and KJZI between 18-22Z. These storms
will tap into moderate instability and very deep moisture,
creating torrential downpours. Conditions during thunderstorms
could rapidly become restrictive. The TAFs will highlight the
potential for thunderstorms with TEMPOs from 18-20Z at KCHS and
KJZI, one hour later at KSAV. Showers could linger into the
overnight hours, however confidence is very low regarding any
potential impacts at the terminals.

Extended Aviation Outlook: A weak front nearby will continue to
provide periods of flight restrictions within any showers and
thunderstorms that develop through Saturday.

&&

.MARINE...
Today through Wednesday: Southwesterly to southerly flow will
persist through Saturday as a weak front moves into the marine
waters from the north. Winds will temporarily become northerly
behind the front Saturday night into Sunday before returning to
a light southwesterly flow by the beginning of next week.

Rip Currents: There is a Moderate Risk for rip currents for all
local beaches today (Friday) due to longer period swell around 8
seconds and enhanced southwesterly wind gusts.

&&

.CLIMATE...
Record High Temperatures:

July 29:
KCHS: 100/1993
KCXM: 99/1999

Record High Minimum Temperatures:

July 23:
KCHS: 80/1991
KCXM: 83/1952

July 24:
KCHS: 81/2024

July 25:
KCHS: 80/2011
KCXM: 82/2016
KSAV: 80/1893

July 26:
KCHS: 78/2025
KSAV: 80/1884

July 28:
KCHS: 80/2025

July 29:
KCHS: 80/2016
KSAV: 82/1878

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Flood Watch from noon EDT today through this evening for
     SCZ043>045-149-150-152.
MARINE...None.

&&

$$

Black/CPM