Barnwell, South Carolina Weather Forecast Discussion

165
FXUS62 KCAE 250021
AFDCAE
Area Forecast Discussion
National Weather Service Columbia SC
821 PM EDT Wed Sep 24 2025
.SYNOPSIS...
Staying mostly dry overnight but the risk for showers and
thunderstorms increases tomorrow into Friday as a cold front
approaches the area. The chance of rain continues into the
weekend and early next week with lower temperatures.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
Key message(s):
- Staying on the dry side overnight but moisture continues to
 increase into Thursday.
Satellite imagery reveals the positively tilted upper trough is
now just west of the Tennessee Valley with an associated
surface cold front in this region as well, extending down
through the Louisiana Gulf Coast. For the CWA, weak 500 mb
height rises continue this evening as upper flow is out of
southwest. In the low levels, winds remain more southeasterly to
southerly, leading to some weak isentropic lift that has
sparked a couple showers near the southern/western CWA, but
these should quickly diminish as flow continues to become more
southwesterly this evening and overnight as a 20-30 kt LLJ sets
up. Moisture will also continue to increase with nearly
unidirectional southwesterly flow overnight and into Thursday
morning, likely aiding in limiting overnight lows toward the
upper 60s to near 70.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Key message(s):
- Rain chances increase on Thursday as a cold front approaches. A
few thunderstorms may be strong with mainly a damaging wind threat.
- Not as hot on Friday with scattered to numerous showers and
thunderstorms possible.
Thursday and Thursday Night: The axis of a positively tilted upper
trough will stretch from southern Michigan southwest to northeastern
Texas at the start of the period, gradually moving eastward. This
will continue to promote southwesterly flow aloft, maintaining warm
air and moisture advection from the Gulf. The attendant cold front
will be located over the Ohio and Tennessee valleys at the start of
the day also making its way eastward towards the FA. PWATs will be
quite high for this time of year, with values increasing to around 2
inches by daybreak Friday. Expect rain chances to increase from west
to east as the day goes on. The SPC maintains a Marginal (1/5) risk
for severe weather across our forecast area. The overall threat will
depend on how much instability can develop ahead of the approaching
cold front and when the anticipated line of convection arrives.
Modeled soundings show 1000-1500 J/kg of CAPE and 20-25 knots of
wind shear which would support the Marginal severe risk with
damaging wind gusts from rain loaded downdrafts being the primary
hazard. Localized flash flooding cannot be ruled out as well.
Daytime temperatures will depend on how much cloud cover there is
and another hot and humid day is possible, particularly across the
southeastern half of the CWA. The current forecast shows a wider
range of values than today with highs ranging from the upper 80s to
lower 90s.
Friday and Friday Night: The upper trough weakens on Friday and may
produce a cutoff low near Tennessee by the end of the period. There
are key differences in its strength between the guidance with the
deterministic GFS showing a closed low while the Euro is weaker and
not quite closed off by daybreak Saturday. At the surface, the cold
front will sluggishly move towards the FA as the day goes on,
keeping the risk of showers and thunderstorms in the forecast. With
the storm system closer to the CWA, rain chances will likely be
higher than on Thursday for most locations. There will be more
clouds around on Friday, both lowering temperatures and instability.
This means that the threat of severe weather will be lower. However,
the threat of excessive rainfall will be higher as indicated by the
Marginal (1/4) risk for the Midlands and CSRA on the latest WPC Day
3 ERO. As mentioned, daytime temperatures should be lower on Friday,
with forecast highs in the 80s.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Key message(s):
- Not as hot as daytime temperatures fall to near normal values.
- The risk of rain remains through the extended.
- Watching a tropical wave in the Caribbean (Invest AL94) for
possible development and impacts.
An upper level low or weak trough is expected to linger to the north
and west for much of the long term. The strength of this feature,
and where it moves, will likely play a pivotal role in the evolution
of the tropical wave designated Invest 94L by the NHC, currently
located near St. Croix in the Virgin Islands. There remains a high
level of uncertainty regarding the track of this tropical wave once
it reaches the Bahamas and while some of the guidance takes the
system near the Southeast US coast, it is still too early to discuss
what, if any, impact the system will have on the Midlands and CSRA.
Due to the presence of the aforementioned upper low, the NBM
maintains a wet pattern, especially on Saturday, with daytime
temperatures around seasonal values.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Convection continues to approach from the west through northern
GA but should dissipate before reaching any of the terminals. A
stronger low level jet of around 25 to 30 knots is forecast
tonight and should help keep surface winds up around 5 knots or
so overnight limiting fog chances, but also do not think we will
reach LLWS criteria. An increasing pressure gradient ahead of an
approaching frontal boundary will support stronger southwesterly
winds with gusts near 20 knots after 15z all terminals. Some
isolated afternoon storms possible but chances too low to
include at this time.
EXTENDED AVIATION OUTLOOK...Moisture continues to increase
leading to likely rain chances and possible widespread
restrictions from late Thursday and into the weekend.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.
&&
$$

NWS CAE Office Area Forecast Discussion