Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
243
FXUS62 KGSP 261045
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
645 AM EDT Sat Jul 26 2025
.SYNOPSIS...
Oppressive heat and humidity build through the weekend, and
continue through the first half of next week. Dangerous heat
indices are possible, especially Sunday through Wednesday.
Afternoon showers and thunderstorms will be isolated except in
the North Carolina mountains. A cold front will finally arrive
late in the week, bringing an increase in showers and storms,
but providing much-needed relief from the heat.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 135 AM Saturday: A large upper-level anticyclone will slowly
retrograde across South Carolina to central GA. This will allow
the heat and humidity to continue to increase across the region
today. High temps are expected to be a degree or two warmer than
yesterday. And with dewpts mixing out to similar to yesterday,
heat indices will be higher and bumping into advisory criteria
across much of the Piedmont this aftn into early evening. No big
changes from the previous forecast, so the Heat Advisory will be
left as is with the morning fcst. Forecast soundings show uncapped
CAPE across the area. So expect scattered to numerous showers
and a few general thunderstorms in the mountains. The Piedmont
is more uncertain, as will need some source of convergence. The
HRRR has been keying in on a subtle boundary draped across the
NC foothills and southern Piedmont (similar to what triggered
convection yesterday). I think with the upper ridge nudging
closer to the area, it should provide some subsidence to really
limit activity. But cannot rule out a few stray showers and a
storm or two outside the mountains. Mentionable PoPs will remain
limited to the mountains and NC foothills, with chances primarily
in the 20-40% range. Chances for severe convection will be low,
but can`t rule out a brief severe updraft pulse associated with
any cell mergers. Whatever convection develops should wane this
evening. Skies should gradually clear out, with another round of
mountain valley fog likely. It will be muggy tonight, with lows
mainly in the mid 70s outside the mountains.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 104 AM EDT Saturday: Little change to the short term forecast
tonight, with sprawling anticyclonic flow aloft still expected to
dominate the pattern through the latter half of this weekend and
into Monday. 500mb heights of up to 598dm will be centered over
the Deep South and Savannah River Valley through the period, which
on Sunday will largely suppress shower and thunderstorm activity
except in the NC mountains, where the high terrain will still
initiate some cells...but without much impactful weather expected.
The bigger story will be the heat; even the 10th percentile of
dewpoint guidance points to significant heat risk across the low
terrain...with heat index values expected to climb above 105 degrees
across a broad swath of the CWA. As such, a Heat Advisory has
been hoisted for Sunday afternoon...and will be allowed to persist
into the first half of the night Sunday night, given that Sunday
night`s lows will only fall into the upper 70s (or even isolated
lower 80s)...providing little relief from oppressive daytime heat.
Monday looks slightly more iffy despite a similar synoptic pattern.
Heights may actually creep up slightly over the area, with low-level
thicknesses alone suggesting Monday will be hotter than Sunday!
Indeed, the 00z suite of operational guidance as well as the latest
cycle of the NBM all point to widespread advisory criteria once
again...potentially even excessive heat warning criteria...but with
a caveat: guidance is in good agreement that Monday will feature a
weak surface boundary dropping off the Cumberland Plateau / Virginia
Piedmont into the Carolinas...serving to modestly drop dewpoints
and galvanizing both cloud cover and convection. The potential
for daytime dewpoint mixing will be all the more present Monday
as a result. All that to say, while some locations on Monday
may indeed get even hotter than Sunday, confidence is much lower
on the dewpoint forecast, and even to an extent the temperature
forecast...so no products have been issued for Monday...pending
future forecast cycles which should hopefully improve confidence.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 139 AM EDT Friday: Deep upper ridging will continue through
the middle of the week, and as a result widespread heat issues
will continue at least through Wednesday. Meanwhile, a robust
500mb low will develop over eastern Canada, gaining momentum
and pivoting into Quebec on Thursday...and resulting in markedly
lowered heights over the Southeastern U.S. This should, at long
last, bring an end to the heat wave. Models begin to diverge
toward the end of the period, but the general consensus is that
sometime on Friday into next weekend, a cold front will dig
out of the Ohio Valley into the Carolinas, spurring an increase
in shower/thunderstorm activity while ushering a cooler, drier
air mass into the region. Despite ensemble variability by this
point, confidence is improving in low severe potential with this
system...as even the more aggressive end of the ensemble envelop
keeps deep shear too low for anything more than loose organization,
and a distinct lack of dry air aloft should keep DCAPE limited.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR is expected thru the period, except for
mountain valley fog early this morning and again tonight. Scattered
mountain convection is expected this aftn, warranting a PROB30
for TSRA at KAVL. The HRRR model has been pretty consistent on a
few showers and isolated storms forming across the NC Piedmont,
and it verified well with yesterday`s convection outside the
mountains. So will add a VCSH at KCLT for the 21z-01z time frame
per the HRRR. Very isolated convection elsewhere, so no mention
in the other TAFs. Winds will favor a SW to WSW direction today,
then toggle to NW this evening and remain light.
Outlook: Mid-summer weather is expected to continue thru at
least the middle of next week, with scattered to numerous diurnal
convection in the mountains, and isolated to scattered convection
in the Piedmont. Low stratus and/or fog will be possible each
morning...mainly in the mtn valleys.
&&
.CLIMATE...
RECORDS FOR 07-26
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 94 1949 72 1911 71 2012 49 1911
1940 2010
KCLT 100 2005 74 1920 76 1992 60 1904
1940 1940
1914 1936
KGSP 99 2010 76 1920 76 2022 53 1911
1995 2005
1987 1940
RECORDS FOR 07-27
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 97 1952 70 1946 72 1936 48 1911
1925
KCLT 103 1940 74 1926 76 2022 57 1920
2016
1944
KGSP 103 1940 70 1946 75 2012 54 1911
1944
RECORDS FOR 07-28
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 98 1952 68 1890 70 2010 53 1895
1878
1877
KCLT 102 1952 70 1890 78 2016 54 1962
KGSP 103 1952 72 1926 76 2016 60 1911
1936 1904
RECORDS FOR 07-29
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 98 1952 67 1984 74 1877 55 1911
1895
KCLT 103 1952 72 1984 77 1993 59 1920
KGSP 104 1952 70 1984 76 1949 59 1911
1936
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...Heat Advisory from noon today to 8 PM EDT this evening for
GAZ028-029.
Heat Advisory from noon Sunday to 2 AM EDT Monday for GAZ028-
029.
NC...Heat Advisory from noon today to 8 PM EDT this evening for
NCZ036-037-056-057-069>072-082.
Heat Advisory from noon Sunday to 2 AM EDT Monday for NCZ036-
037-056-057-069>072-082.
SC...Heat Advisory from noon today to 8 PM EDT this evening for
SCZ009>014-019-107-109.
Heat Advisory from noon Sunday to 2 AM EDT Monday for
SCZ008>014-019-107-109.
&&
$$
SYNOPSIS...MPR
NEAR TERM...ARK
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...ARK
CLIMATE...