956
FXUS62 KGSP 301804
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
204 PM EDT Wed Jul 30 2025

.SYNOPSIS...
The heat wave continues to gradually weaken through Friday as the
upper pattern slowly shifts and brings a cold front down from the
north. The front should move across the area Friday and Friday
night, bringing some much-needed relief from the heat in the form
of below normal temperatures this weekend into early next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 155 PM EDT Wednesday: Ridgetop convection and garden variety
activity developing elsewhere should gradually grow in coverage
over the next few hours. 2000-3000 J/kg of SBCAPE, 600-1000 J/kg
of DCAPE, and very little deep layer shear suggest storm mode
through this afternoon will support pulse convection carried by
outflow boundaries. PWAT values of 1.75"-2.00+" indicate that a
localized hydro threat will be possible thanks to heavy rainfall
rates and slow moving storms. A few strong to severe storms can`t
be ruled out, with wet microbursts being the primary threat. CAMs
are in decent agreement with dwindling convective coverage shortly
after sunset, with only isolated showers and thunderstorms through
midnight or so. Dewpoints remain elevated in the low 70s, but
enough mixing in the boundary layer and morning cloud cover has
kept temperatures in check, with most locations only in the upper
80s to low 90s outside of the mountains, which has allowed for
heat indices to remain below Advisory criteria.

Leftover cloud debris will be present through the early overnight
hours and ground fog may develop where cloud cover clears quicker
than expected and where heavy rainfall occurred. Mountain valley fog
and low stratus is expected again, while boundary layers struggle
to fully decouple overnight with wider dewpoint depressions. In
this case, not expecting widespread coverage in low stratus and
fog by daybreak Thursday compared to this morning. Overnight lows
will remain in the low to mid 70s. Weakness in the flow aloft will
be evident as an upper trough over the northeastern CONUS slowly
digs south into the region. The subtropical ridge that has plastered
the area with extreme heat will be well west of the area by the end
of the forecast period. Another area to watch is the formation of
a weak anticyclone aloft over Florida. Between the ridge over the
Southern High Plains and anticyclone over Florida, moist south to
southwesterly flow will filter into the region and set the stage
for another diurnally driven convective day for Thursday.

With the upper trough slowly digging south towards the area, an
attendant frontal boundary will also be knocking on the backdoor to
the northwest. With the added forcing from the frontal boundary to
go along with an environment that`s very similar to the past few
days with 2000-3000 J/kg of SBCAPE, 600-1000 J/kg of DCAPE, and
very little deep layer shear, expect convective coverage to become
more widespread during peak heating Thursday. Ridgetop initiation
is evident to go along with initiation solely from the added forcing
for ascent across the mountains and will shift south and east later
into the afternoon. A few induced cold pools may develop, which
would help to slightly elevate the severe potential. Not outlooked
at the moment from SPC, but can`t rule out a small marginal risk
due to this potential. Increased compressional warming ahead of the
boundary and dewpoints continuing to hover in the low to mid 70s,
wouldn`t be surprised if a few locations outside of the mountains
flirt with Heat Advisory criteria indices on Thursday. Afternoon
highs on Thursday will be in the low to mid 90s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 1252 PM EDT Wednesday...the morning guidance blend continues
to trend warmer for Friday as a frontal zone drops down from the
north. On the one hand, the frontal boundary will be the focus for
widespread/numerous mainly afternoon/evening showers and storms,
with plenty of clouds, both of which would tend to cut down on
the potential for high temps getting up into the low/mid 90s. On
the other hand, there won`t really be much of an air mass change
on Friday and we should get yet another warm start to the day,
so we could easily reach the 90s east of the mtns before all
the convection really gets going. There`s an outside shot at
reaching Heat Advisory criteria in a few spots, but for now we
are limiting the apparent temps below 105. As per usual, the shear
will be relatively weak but there should be enough sfc-based CAPE
and dCAPE to support a few wet microburst producers. Confidence
is running high that Friday will be the end of our long streak
in the 90s. The transition should occur Friday night into early
Saturday as the mid/upper trof in the East continues to slowly
amplify over the East Coast and the sfc high over the Great Lakes
starts to wedge down east of the mtns, pushing the frontal zone
south of the fcst area. We still expect Saturday to feel a whole
lot different and cooler as high pressure takes up residence to
our north and supports a weak summertime wedge scenario. Easterly
flow and weak upglide should keep clouds around well into the
day with some low level forcing to account for shower activity,
especially over the mtns down through the Savannah R basin. High
temps are projected to be on the order of ten degrees below normal,
but this could go a category either way.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 136 PM EDT Wednesday...our weak summertime wedge should be
established across the area by Saturday night. The overall pattern
in the northern stream changes only slowly Sunday through Monday
as the parent high drifts off the coast of New England and the
Maritime Provinces but leaves behind a remnant over the Mid-Atlantic
region. The cooler easterly flow should keep temps 5-10 degrees
below normal Sunday and five below normal Monday as the air mass
slowly modifies. The model blend keeps a chance of precip across
the entire region both days but this is accepted with a healthy
dose of skepticism. Fcst soundings from the GFS, for example,
would suggest that most of the fcst area would remain precip-free,
so don`t get your hopes up too much for additional rain. The
expectation is that by Tuesday, the remnant wedge will be draining
away and temps will be climbing back up toward normal. There is much
uncertainty regarding the return flow of moisture from the south,
but much of the guidance digs another short wave to our immediate
west by that time. Depending on how quick this develops, we could
see a resurgence in confidence of scattered/numerous showers and
storms. By Wednesday, we should be back to good old normal summer
temps and precip probs, with an outside chance of getting some
kind of organized convection dropping in from the northwest.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Fog and low stratus has lifted and
scattered out across the area. Now the attention turns to the
showers and thunderstorms that have developed. All TAF sites
have a TEMPO for TSRA and associated restrictions through peak
heating. Can`t rule out a rogue shower or thunderstorm late into
the evening, but confidence was too low for anything more than
a VCSH mention. Otherwise, another round of low stratus and
fog may develop, especially in the mountain valleys overnight
tonight. Placed a TEMPO before daybreak Thursday at KAVL for 1/2SM
vsby and OVC002 cig as a result. A mention of potential restrictions
are placed at the rest of the TAF sites, with KAND and KHKY being
the likely culprits based on current model trends. Winds will become
light and variable overnight as well to go along with some form
of convective debris. Another round of showers and thunderstorms
are expected Thursday afternoon and evening, so placed a PROB30
mention at KCLT and will likely need a PROB30 at all other TAF
sites during the 00Z update, when the forecast period extends that
far out. South to southwesterly winds are expected through much
of the daytime period Thursday.

Outlook: Scattered showers and thunderstorms each afternoon
through Saturday. Low stratus and/or fog is possible each morning,
especially in the mountain valleys.

&&

.CLIMATE...
RECORDS FOR 07-30

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1954     68 1936     72 2011     54 2014
                                        1878        1897
                                                    1895
   KCLT     101 2011     71 1981     77 1953     58 1914
                                        1941
   KGSP     101 1999     73 1981     77 2011     60 1914
                                                    1911
                                                    1884



RECORDS FOR 07-31

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      95 1999     65 1936     71 2011     53 1986
                                                    1914
   KCLT     100 1999     69 1936     77 1941     56 1914
                1931                    1931
                1915
   KGSP     104 1999     71 2014     78 1999     56 1936
                                        1931

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...CAC
SHORT TERM...PM
LONG TERM...PM
AVIATION...CAC
CLIMATE...