883
FXUS62 KGSP 180557
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
157 AM EDT Mon Aug 18 2025

.SYNOPSIS...
Hot and humid weather today with scattered thunderstorms over the
mountains, and a few stray showers or storms elsewhere. Precip
chances trend higher for Tuesday with temperatures trending cooler
and back to near normal for the middle of the week. Rain chances
increase at the end of the week with temperatures trending a few
degrees below normal at that time.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1230 AM Mon: Surface analysis shows a narrow trough extending
from Cape Cod southwest to Virginia at this hour, associated with
a weak cold front at the leading edge of a Canadian airmass. The
front will track southward and across our CWA by tonight. Initially
this morning we will remain under nebulous forcing, effectively from
the influence of the deep ridge in the central CONUS. Skies will be
mostly clear. Winds are presently calm at many obs sites but may
pick up slightly before daybreak as the front drifts into NC. The
winds likely will develop too late to completely inhibit development
of mountain valley fog and along some rivers outside the mountains.

Winds will favor NE in most areas after daybreak as northerly
winds mix down near and ahead of the front. Prog soundings depict
mediocre lapse rates aloft as is typical for this year, but without
any actual cap. The front will provide some lift in what otherwise
would be a virtually unforced environment. Developing easterly flow
will bring diurnal mountain PoPs back to near climo, 30-50%. PWATs
trend upward near the front which could promote initial updrafts
via reduced entrainment, though dry air will remain above 600 mb
or so. CAMs largely depict scattered convection blossoming near
the front this aftn/evening near the NC/SC border, mainly east
of Charlotte, and to some extent along the east-facing Blue Ridge
Escarpment in the evening as 850mb flow veers more toward SE. It is
conceivable some showers could also develop in GA/SC west of I-26
this evening. The non-mountain areas mostly see PoPs peak at 20-30%
around or after 00z, with chances slowly declining tonight, lasting
longest along the Escarpment. The east to southeast low-level flow
looks to be associated with stratus development over most of the
CWA in the wee hours of Tuesday. The Canadian high will push to the
Northeast Coast by around daybreak Tuesday. The high is too weak to
declare true CAD at that time, but hybrid CAD could develop Tuesday.

With moisture pooling near the front, and with temps trending a
degree or two warmer vice Sunday, a few spots southeast of I-85
should see heat index exceed 100 this afternoon.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
As of 1:45 AM EDT Monday: The short-term forecast picks up at 12z on
Tuesday with our area under the eastern extent of broad upper ridging
that covers most of the CONUS. Over the next 24 to 36 hrs, the eastern
periphery of the ridge will retreat westward as long wave upper trofing
amplifies to our north over eastern Canada. By the end of the period
early Thursday, the trof will begin to lift NE as the ridge expands
eastward again. At the sfc, Canadian high pressure will be centered
just north of New England with NELY low-level flow persisting over
the western Carolinas as the period begins. Over the next couple of
days, the high will gradually slide further east and off of the New
England Coast. At the same time, Hurricane Erin will approach the
Carolina Coast and then turn northward as the period ends early
Thursday. Overall, I still expect sct showers with some embedded
thunder on Tuesday as strengthening NELY flow from TC Erin will
bring some amount of deeper Atlantic moisture over our area. Wed
is looking a bit drier overall especially outside of the mtns, but
I still have above climo PoPs across the higher terrain for the aftn
and evening. The severe potential still looks minimal at best either
day, but I wouldn`t totally rule out a few stronger storms on Tues.
Temperatures should moderate a decent amount under more cloud cover
and weak wedging on Tues with highs expected to remain a few degrees
below normal.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 1:25 AM EDT Monday: The extended fcst picks up at 12z on
Thursday with long wave upper trofing lifting NE of New England
with heights recovering marginally over the Southeast. This will
be short-lived though, as another broad upper trof is expected to
amplify southward and over the Great Lakes by early Saturday. The
trof is expected to dig further south thru the weekend and into
early next week as the period ends. At the sfc, broad high pressure
will be centered to our north while Hurricane Erin is expected to
be centered just off the Carolina Coast as the period begins early
Thursday. Over the next couple of days, Erin will turn NE and move
further off the Atlantic Coast as another Canadian high approaches
our area from the NW. It remains unclear how far the high will move
southward and whether it will produce significant drying over our
area late in the period. Regardless, we can expect a broad area of
moist, low-level convergence across the Southeast from Thurs thru
most of the weekend with diurnal PoPs increasing each day thru Sat
and decreasing on Sunday and Monday. The severe potential still
appears minimal thru the period, however with a moist airmass
expected to persist over the region thru most of the period, the
potential for localized flooding will likely be the main concern.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Largely calm winds early this morning;
a few sites are reporting nearly due W winds should turn more NE
with time, but speeds will be light and some VRB is expected thru
late morning. Aside from a few patches of stratocu skies will be
mostly clear and TEMPOs for fog/stratus at KAVL and KHKY have been
retained near daybreak. Diurnal cu will form near MVFR threshold
around 14-15z then mix comfortably into VFR range. A seasonable
diurnal TSRA threat is expected for the mountains, prompting PROB30
at KAVL. These storms will be capable of gusty/erratic winds. The
better chance at the other sites is after peak heating, particularly
after 23z, along weak backdoor cold front pushing south thru the
area. Chance is still too small to mention at KCLT and KAND but the
other sites get VCSH. Convective model trends will be monitored
this morning and later issuances could add VCSH there, and can`t
rule out need for PROB30s elsewhere if confidence increases on
location/timing. The front will reinforce predominately NE winds
today outside the mountains, and in its wake, moist easterly flow
aloft looks to produce widespread stratus across the area after
06z Tue.

Outlook: Nocturnal stratus will slowly erode Tue over most
of the area, with a chance of SHRA/TSRA at all terminals Tue
as well. Afternoon showers and thunderstorms with associated
restrictions are expected mainly across the mtns Wed. More
widespread convection expected at all terminals Thu-Fri. Morning fog
and low stratus are also possible, especially across the mountain
valleys each day.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...Wimberley
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...Wimberley