Seigling, South Carolina Weather Forecast Discussion

865
FXUS62 KCHS 231110
AFDCHS
Area Forecast Discussion
National Weather Service Charleston SC
710 AM EDT Tue Sep 23 2025
.SYNOPSIS...
High pressure north of the region will weaken throughout the
day. A slow moving storm system could affect the area later
this week and into the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, the mid-level flow is expected to become more
zonal as the embedded shortwave continues to deamplify and get
absorbed into the broader flow. At the surface, the center of
the high will sit off the Mid Atlantic coast in the morning and
continue to extend across GA and the Carolinas. The offshore
trough will continue to generate showers and thunderstorms
across the coastal waters in the morning before the trough
washes out through the afternoon. As the high over the Atlantic
becomes the primary feature, the low-level flow regime will
transition from northeasterly in the morning to become more
onshore and southeasterly through the afternoon. Concerning
convective chances for today, model guidance is providing some
mixed signals. We are largely devoid of any notable forcing
features so development will hinge largely on surface heating
and destabilization. If there is some hint of consistency among
the hi- res models and the HREF it is that the main area at risk
of isolated to scattered showers and storms is across the Tri-
County in the early to mid afternoon hours. This would be the
area across Berkeley, inner Charleston, and southern Dorchester
counties, just inland of the coast. Instability won`t be
sufficient to support any severe threat, but it is possible
there could be a few pockets of some brief moderate to heavy
rainfall if showers and storms develop. Highs are forecast to be
a couple of degrees warmer today, with upper 80s away from the
coast for southeast SC, and upper 80s to low 90s for southeast
GA.
Tonight: Any lingering convection from the afternoon will
dissipate quickly in the early evening hours with the rest of
the overnight expected to be dry. Low-level flow will turn more
southerly with time, resulting in some warmer temperatures than
the last few nights. Lows are forecast in the upper 60s inland,
with low 70s along the coast.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
After any morning fog lifts/burns off, the region remains
between the Atlantic high pressure to our east and a low
pressure over the plains to the west, resulting in warm/hot
temperatures for Wednesday. 850mb temperatures climb towards the
18 deg C mark throughout the day, and as we hit peak heating in
the afternoon temperatures will rise up into the lower to mid
90s for those inland and into the upper 80s along the coast. An
afternoon sea-breeze is expected, but will do little to provide
relief aside from the increase in wind speeds behind it. With
weak ridging aloft and lack of forcing mechanisms (aside from
the sea-breeze), convection- allowing models (CAMs) are showing
a dry forecast for the region Wednesday afternoon and evening.
The sea-breeze is expected to bring dewpoints up into the mid
70s, which will help to moderate overnight lows into the lower
70s into Thursday.
Expect a similar/warmer repeat of Wednesday for Thursday, as
the surface low lifts across the Great Lakes region and the
attached cold front making its way towards the area from the
west. With 850mb temperatures remaining right around the 18 deg
C mark, afternoon highs will again peak into the lower to mid
90s inland, and upper 80s along the coast. However, the GEFS
would suggest we begin to see an increase in cloud coverage as
shortwaves aloft begin to move across the region ahead of the
approaching main wave, so if that were to occur expect to see a
few degrees knocked off the high temperature. Ensemble consensus
is for the aforementioned shortwaves to start moving across the
region during the evening hours, with chances decreasing into
the morning hours on Friday. Overnight temperatures dip into the
upper 60s to lower 70s by Friday morning.
While we will likely see a break from the rain for a few hours
on Friday, chances for rain return during the afternoon hours as
additional shortwaves begin to lift from the base of the slow
moving upper level trough. Further support arrives from the
upper level jet as it slides the right entrance region over the
area, which would provide synoptic-scale upward vertical motion,
in addition to having the aforementioned surface cold front
nearby. Given the numerous forcing mechanisms for showers and
thunderstorms, WPC does have the area outlined with a marginal
risk (level 1 out of 4) for excessive rainfall. While chances
for severe weather look to be low (

NWS CHS Office Area Forecast Discussion