Anderson, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

518
FXUS62 KGSP 221437
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 AM EDT Sun Jun 22 2025

.SYNOPSIS...
The heat and humidity will gradually increase through mid-week as a
hot upper ridge builds over the Southeast region of the country.
Isolated showers and thunderstorms remain possible each afternoon
and evening, mainly across the mountains through Tuesday. The heat
and humidity sticks around through the rest of the week with daily
shower and thunderstorm chances expanding east of the mountains
from Wednesday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 AM Sunday: A large upper anticyclone will continue
to strengthen as its center drifts from the Ohio Valley to the
Central Appalachians by 12z Monday. Heat continues to build
under the high, and max temps are expected to be 2-3 degrees warmer
than yesterday...with highs in the mid 90s across the Piedmont and
around 90 in the lower mountain valleys. Surface dewpoints should
mix out slightly and keep heat indices within a couple of degrees of
the ambient temps...still some Piedmont locations could see the heat
index briefly hit the century mark. Despite a mid-level subsidence
inversion, there should be enough instability for isolated to widely
scattered showers and general thunderstorms to redevelop across the
NC mountains this aftn. Steering flow will turn out of the
ESE...allowing any activity to drift toward TN. Meanwhile, the
Piedmont should see just some cu with a stray shower or two
possible. Tonight should be quiet, with some mountain valley fog.
Lows will be a few degrees above normal, mainly in the lower to mid
70s in the Piedmont and 60s in the mountain valleys.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 100 AM EDT Sunday...

Key Messages:

1) Heat and Humidity Cranks Up through the Period with Well Above
Normal Temps Expected

2) Heat Indices Climb into the Upper 90s to Lower 100s East of the
Mountains Each Afternoon, with the Most Oppressive Conditions
Expected Tuesday

3) Isolated Diurnal Convection Possible in the Mountains Each Day

Strong, hot upper anticyclone remains parked over the eastern United
States through the short term allowing the heat and humidity to
crank up. With both high and low temps running ~7-12 degrees above
normal for this time of year, the heat wave will linger through the
forecast period. Highs each afternoon will reach into the lower 90s
across the mountain valleys and the mid to upper 90s east of the
mountains. Once again blended in some NBM 10th percentile to the
dewpoints through the period with NBM dewpoints remaining on the
higher end of guidance, and with decent mixing expected each
afternoon. Heat indices each afternoon will range from the upper 90s
to lower 100s, mainly east of the mountains. Confidence is high that
heat indices will remain below Heat Advisory criteria (starts at 105
degrees F) on Monday with the LREF showing a 10% chance or less of
heat indices exceeding 104 degree F CWA-wide. As the humidity cranks
up Tuesday, heat indices will climb near advisory criteria east of
the mountains, with some locations along/near I-77 and the Upper
Savannah River Valley potentially reaching advisory criteria.
However, confidence remains low regarding this potential as the LREF
only shows a 15% to 20% chance of heat indices exceeding 104 degrees
F across these locations. Mainly diurnal and isolated convection is
expected across the mountains each day. The strong upper ridge may
act to suppress convection somewhat so capped PoPs to slight chance
(15% to 24%) across the mountains through the period. Winds will
remain light so no relief is expected from the heat and humidity,
unless you are lucky enough have an isolated shower or thunderstorm
develop overhead. It will remain warm and muggy each night so those
without access to air conditioning will have a harder time cooling
off, especially those living in urban areas (due to the urban heat
island effect).

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 130 AM EDT Sunday...

Key Messages:

1) Heat Wave Continues through the Long Term with the Most
Oppressive Conditions Expected Wednesday and Thursday

2) Heat Advisory Criteria is Possible Along/Near I-77 and the Upper
Savannah River Valley Each Afternoon through at Least Friday

3) Diurnal Convection Possible Across the Entire Forecast through
the Period

The anticyclone lingers over the region through the long term but
will gradually weaken after Wednesday. Thus, the heat and humidity
will continue cranking up through at least mid-week before slightly
decreasing late-week into the weekend. Despite the upper ridge
weakening, not much relief from the heat and humidity is expected
Friday into the weekend. The most oppressive conditions through the
long term can be expected Wednesday and Thursday. Highs on Wednesday
and Thursday will climb into the lower to mid 90s across the
mountain valleys with the mid to upper 90s expected east of the
mountains. The NBM actually had some locations east of the mountains
reaching into the triple digits on Wednesday but opted to blend in
some of the NBM 25th percentile to ensure triple digit highs would
be limited (since it`s hard to reach 100 degrees F this time of
year). Highs Friday into the weekend will range from the upper 80s
to lower 90s across the mountain valleys and the lower to mid 90s
east of the mountains. Did blend in some of the NBM 10th percentile
into the NBM dewpoints again as they continue running on the higher
end of guidance, and as decent mixing is expected each afternoon.
Heat indices east of the mountains will continue to range mostly
from the upper 90s to lower 100s each afternoon. The LREF depicts a
roughly 20% to 40% chance of heat indices exceeding 104 degrees F
along and south of I-85 through Saturday. So, confidence on reaching
advisory criteria (which starts at 105 degrees F) remains low to
moderate through the period. Mainly diurnal shower and thunderstorm
chances will gradually increase through the short term as the ridge
gradually weakens, with even areas east of the mountains expected to
see activity develop. Winds will remain light so no relief is
expected from the heat and humidity, unless you are lucky enough
have showers and thunderstorms develop overhead. It will remain warm
and muggy each night so those without access to air conditioning
will have a harder time cooling off, especially those living in
urban areas (due to the urban heat island effect).

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions prevail as high pressure
remains overhead. Isolated to widely scattered SHRA and TSRA will
develop across the higher NC mtn ridgetops and generally drift NW
toward the TN border. So confidence on any near KAVL remains too
low for any mention in the TAF. A stray shower or storm cannot
be ruled out across the Piedmont. Wind will be very light and
quite VRB thru the period, but favor a S or SE direction this
aftn. There has been a little fog around KHKY the last couple of
nights, including today. So will add a TEMPO for some MVFR vsby
there for the same time period tonight.

Outlook: Dry conditions to persist thru at least Wednesday. A
return to more typical diurnal convection coverage expected late
in the week. Fog and/or low stratus will be possible each morning
in the usual mtn valleys and near lakes and rivers.

&&

.CLIMATE...
RECORDS FOR 06-23

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 2016     64 1936     70 2017     47 1947
                1988
   KCLT     100 2015     63 1936     77 2016     53 1947
   KGSP      99 1988     70 1900     75 2016     54 1972
                1944                                1947



RECORDS FOR 06-24

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      94 1952     66 1991     70 2015     48 1947
                            1919                    1918
   KCLT     102 1930     68 1936     76 1998     55 1972
                                        1914        1936
   KGSP     100 1952     64 1936     76 2016     51 1915



RECORDS FOR 06-25

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      96 1952     63 1889     69 1949     45 1972
                                        1943
                                        1891
   KCLT     102 1914     70 1980     75 1952     53 1889
                            1915        1914
                            1889
   KGSP     101 1952     69 1980     75 1931     52 1972
                                        1925



RECORDS FOR 06-26

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      96 1948     65 1961     69 1952     49 1984
                                                    1974
   KCLT     102 1952     68 1965     78 1948     55 1979
   KGSP     100 1952     71 1991     77 1952     55 1979
                1934                                1974
                1914

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...ARK/JDL
SHORT TERM...AR
LONG TERM...AR
AVIATION...ARK
CLIMATE...GSP