Manassas, Georgia Weather Forecast Discussion

006
FXUS62 KCHS 201111
AFDCHS
Area Forecast Discussion
National Weather Service Charleston SC
711 AM EDT Sat Sep 20 2025
.SYNOPSIS...
High pressure will prevail through the middle of next week. A
cold front may approach the area by late week with an
increasing threat for unsettled weather.
&&
.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, while the main trough axis will shift off to the
east through the day, the forecast area will remain within the
influence of the broader troughing pattern in place. The surface
pattern will remain weakly forced and poorly defined with weak
high pressure allowing northeast flow in the morning to
transition to onshore easterly or southeasterly flow by the
afternoon. The general consensus among the hi-res model
solutions is that there will again be isolated diurnal
convection this afternoon, and this is supported by the HREF as
well. However, model soundings are certainly not impressive
featuring warm mid-levels which will limit the depth and
strength of any updrafts that form. Therefore, we have added in
a tier of 20 percent rain chances primarily including interior
southeast GA/SC. There is virtually no severe risk, but it is
possible that locations directly under any showers or storms
could experience a brief period of moderate to heavy rainfall.
Temperatures appear to continue the above normal trend with
upper 80s to low 90s away from the immediate coast.
Tonight: Any convection lingering in the early evening should
dissipate quickly with the loss of heating and the rest of the
overnight is expected to be dry. The pattern will change a bit
through the overnight as the surface high parked across New
England will build down into the region late tonight. The
gradient will tighten in response to the building high and a
weak surface wave noted offshore. Therefore, we should see a
modest increase in northeast flow late tonight. This should
allow for slightly cooler overnight lows, with mid 60s more
common inland and upper 60s along the coast.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Deep layer ridging will dominate the eastern and southeastern
U.S. through early Monday, then begin to weaken and move
eastward later Monday and Tuesday. At the surface, a wedge of
high pressure will build southward into our forecast region,
resulting in increasing northeast flow through early Monday.
Lack of sufficient moisture and forcing will translate into
little/no chances for significant precipitation on Sunday, and
possibly isolated convection by Monday, especially over our GA
zones, as deep layer moisture begins to increase with more
south-southeast low level flow.
Temperatures are expected to generally be near normal through
the period. Highs in the mid to upper 80s, possibly touching 90
over our inland GA zones by Tuesday. Lows in the mid 60s to
lower 70s, warmest near the coast.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Models seem to be in better agreement through much of this
period as compared to solutions from this time last night. The
latest deterministic run from the GFS as well as the Canadian
seem to be matching closer to the ensemble mean solutions,
showing a closed upper low forming over the Central U.S. by
Wednesday and Thursday. The latest ECMWF is not in yet, but the
previous 12Z run had a similar solution, if not a tad stronger
and further south with the upper low. This upper low then looks
to weaken and move slowly northeastward into the OH River Valley
by later Friday and Saturday.
Overall, expect the low level flow to veer to east-southeast
Wednesday through Friday. A gradual increase in deep layer
moisture will result in isolated showers and thunderstorms
Wednesday, possibly becoming more scattered by Thursday and
Friday. Figuring out which day will have the best chances for
precip will depend on the placement of the associated surface
front with the upper low, which could swing into the area from
the west later Thursday through early Friday.
Temperatures warming to above normal through Thursday, then
possibly falling back to near to slightly below normal Friday
and Saturday. Seems the blended model forecasts for high
temperatures on Wednesday and Thursday may be a tad high given
the upper pattern, but have left for now given uncertainty.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
The 12z TAF period begins with mostly shallow ground fog being
reported around the area including at KCHS, KJZI, and KSAV. The
fog will not last long this morning and is expected to dissipate
quickly once the sun comes up and we begin to warm and mix.
Then in the afternoon, there should again be isolated showers
and thunderstorms. However, current thinking is that anything
that does develop should remain inland of the terminals. Of the
3 TAF sites, KCHS stands the best chance of seeing a shower or
thunderstorm though this probability remains low overall.
Extended Aviation Forecast: Expect VFR conditions to prevail at
all sites through at least early week/Tuesday. Increasing deep
layer moisture may increase enough by Tuesday and Wednesday to
result in isolated afternoon showers and thunderstorms with the
potential for brief flight restrictions.
&&
.MARINE...
Today through tonight: Northeast flow should mostly prevail
through the day, though the waters closer to the coast should
turn more easterly this afternoon and evening in response to the
sea breeze. Wind speeds should mostly top out in the 10-15 knot
range. Expect more northeast through the overnight with a bit
of surge expected late. By sunrise Sunday wind speeds should
increase into the 15-20 knot range across all the local waters.
Seas should mostly average 2-3 feet today, becoming 3-4 feet by
sunrise Sunday.
Through Monday, a wedge of high pressure will build inland as a
trough of lower pressure forms over the Atlantic waters. This
will result in northeast winds of 15-20 knots, with some gusts
near 25 knots possible. Seas generally 3 to 5 feet. At this
time, still expect conditions to remain below SCA levels.
Tuesday and Wednesday, the wedge of inland high pressure
weakens and moves eastward, with low level winds decreasing and
veering to more east and southeast. Winds generally 15 knots or
less and seas 2 to 4 feet through this period.
Rip Currents: Increasing risk for rip currents expected this
weekend as gusty northeast winds develop between strong inland
wedge of high pressure, and coastal troughing over the Atlantic
waters. In addition, increasing swell from the southeast will
also favor a Moderate Risk of rip currents along Georgia beaches
today. Expect a Moderate risk for rip currents for all beaches
on Sunday.
&&
.TIDES/COASTAL FLOODING...
Strong northeasterly winds are expected to create larger tidal
departures this weekend, which could result in tide levels
approaching 7 ft MLLW (minor) in Charleston Harbor starting with
the Saturday evening high tide cycle. The risk for minor
coastal flooding should continue into early next week. Coastal
Flood Advisories could eventually be needed for minor saltwater
flooding in Charleston and Coastal Colleton Counties.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...BSH
SHORT TERM...RFM
LONG TERM...BSH/RFM
AVIATION...BSH/RFM
MARINE...BSH/RFM

NWS CHS Office Area Forecast Discussion