Summerville, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

998
FXUS62 KCHS 250020
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
820 PM EDT Fri Jul 24 2026

.WHAT HAS CHANGED...
Aviation and marine sections updated.

&&

.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 again 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 again Saturday.

Rest of today: A threat for locally heavy rainfall will remain
possible into the evening hours tonight. This is expected as the
observed sea-breeze continues to push inland, with a slow/stalled
front remaining in/near northern Dorchester/Berkeley/Colleton
counties in South Carolina and into central Georgia this evening.
The first round of showers and thunderstorms are ongoing, and are
expected to expand across the rest of South Carolina with lesser
areal coverage expected to reach down into southeastern Georgia. As
temperatures have climbed into the lower to upper 90s, instability
values have risen into the 1500-2000 J/kg range, and while most of
the CAPE profiles are long and skinny (generally a heavy rain
signature), isolated stronger wind gusts in the 50-60 mph range
cannot be ruled out.

The main threat continues to be heavy rainfall, given PWATs of 2.0-
2.4" and dew points in the lower to upper 70s. In addition, slow
storm motions are anticipated from Corfidi vectors remaining in the
5-10 knot range, leading to locally heavy downpours being possible.
Thunderstorms will be capable of producing a 1-3 inches per hour,
with scattered total rainfall amounts of 1-3 inches. Locations that
see multiple rounds of rainfall may see 5+ inches, which remains
covered well by the existing Flash Flood Watch across the Charleston
quad-county region. 12Z HREF guidance has come in a touch lower for
both 1"/3hr and 3"/3hr probabilities compared to the 00Z run, now
carrying a 70% chance for an inch in three hours, and a 30% chance
for 3 inches in three hours, mostly for portions of southeast South
Carolina though the risk does spill over into portions of southeast
Georgia. The 12Z REFS is little more aggressive, keeping scattered
50% chances for 3"/6hr for both southeast South Carolina and
southeast Georgia this afternoon/evening, so be alert to the
possibility of flash flooding even if you are outside the current
watch. The main timeframe for heavy downpours today is from 3-9 PM.

Saturday: A mid-level trough will be over most of the East Coast,
with it`s axis shifting eastward as time progresses. Additionally,
there will be several subtle shortwaves moving through the broader
flow. At the surface, the stationary front will be over the
Charleston Tri-County or just north of this area. There will be a
large area of very deep moisture across the Southeast U.S. PWATs
should peak in the 2.25-2.5" range across our area. This would be
near record values for CHS per SPC Sounding Climatology and 2-3
standard deviations according to NAEFS. The combination of lift from
the front along with the deep moisture will generate numerous to
widespread showers and thunderstorms across our area. They`ll likely
ongoing early in the morning, mainly north of I-26. But the coverage
and intensity will increase into the afternoon, especially along the
seabreeze. Though, both the deterministic models and the CAMs point
towards the higher QPF amounts being along the immediate coast.
Rainfall productions should be very efficient and weak steering
winds should cause storms to move very slowly and/or stay in place.
If heavy rainfall occurs over the Charleston and/or Savannah metro
areas, then flash flooding concerns would quickly escalate,
especially if there are saturated soils from Friday`s rainfall.
Therefore, WPC has most of our SC counties under a Slight Risk for
Excessive Rainfall. The rainfall should gradually decrease in both
intensity and coverage Saturday evening and overnight.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
25/00z Aviation Discussion:
KCHS/KJZI/KSAV: Risk for tstms is diminishing at all terminals.
Risk will increase again Saturday afternoon for all sites. Risk
highest roughly 20-00z, maybe a tad earlier at KCHS and KJZI.

Extended Aviation Outlook: A stationary front nearby will
continue to bring periods of flight restrictions through Sunday
due to showers and thunderstorms.

&&

.MARINE...
Tonight: Southerly wind regime will persist. Winds 15 kt or less
with seas 2-3 ft.

Saturday through Wednesday: A stationary front nearby will
bring southwesterly winds on Saturday. Winds will briefly veer
to the north and northeast on Sunday, then again Monday morning,
followed by a shift to the southeast Monday afternoon. Winds
will become elevated Tuesday night into Wednesday, so Small
Craft Advisories may be needed for portions of our waters.

&&

.CLIMATE...

Record High Minimum Temperatures:

July 24:
KCHS: 81/2024

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

July 29:
KCHS: 80/2016

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...Flood Watch until midnight EDT tonight for SCZ043>045-149-150-
     152.
MARINE...None.

&&

$$