Severe Thunderstorm Warning 84, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
111 PM EDT Tue Jun 30 2026

.WHAT HAS CHANGED...
Confidence is increasing that a more typical summer pattern will
return late weekend into early next week with seasonable
temperatures and daily storm chances.

Updated the aviation discussion for the 18Z TAFs.

&&

.KEY MESSAGES...
1. Heat risk will steadily increase through the week, with heat
indices likely exceeding 100 degrees across much of the Piedmont
and foothills, especially by mid to late week. Daily thunderstorms
will also be possible across the mountains.
2. The heat threat begins to wane late weekend and into early
next week with a return to a more traditional mid summer pattern
featuring seasonable temperatures and daily storm chances.

&&

.DISCUSSION...
Key message 1: Heat risk will steadily increase through the week,
with heat indices likely exceeding 100 degrees across much of
the Piedmont and foothills, especially by mid to late week. Daily
thunderstorms will also be possible across the mountains.

The synoptic pattern starts off rather amplified today with a deep
trough digging through the Great Basin while an anomalous upper
ridge continues to build over the Tennessee Valley. With time, the
upper ridge will migrate into the Southern Appalachians by late week
through the 4th of July holiday weekend bringing a round of hot
temperatures to the area. 500mb heights and 850mb temperatures will
both be in the 99th percentile for early July, which will support
hot afternoon high temperatures in the upper 90s to low 100s. Even
mountain valleys will be warm with highs in the low to mid 90s.

While temperatures will definitely be hot, the main uncertainty is
whether we will reach heat advisory criteria with heat indices of
105 degrees or greater. Forecast soundings continue to depict a
deeply mixed boundary layer extending to nearly 700mb. This deep
mixing will support aggressive mixing out of dewpoints with surface
dewpoints potentially falling as low as the upper 50s to low 60s.
The lack of a more humid airmass will generally preclude heat index
values reaching advisory criteria. That being said, precautions will
still need to be taken as air temperatures in the low 100s will
still pose a risk of heat related illness.

Additionally, diurnally driven thunderstorms will be possible across
the mountains each afternoon where terrain effects will be
sufficient to overcome an otherwise unfavorable environment for
convective initiation. What storms do develop will have the
potential to become strong to severe owing to moderate to high
instability, steep lapse rates, and modest DCAPE. The main threat
would be for locally damaging winds and small hail.

Key message 2: The heat threat begins to wane late weekend and into
early next week with a return to a more traditional mid summer
pattern featuring seasonable temperatures and daily storm chances.

By Sunday, the upper ridge associated with the holiday heat wave
will have weakened and will be shifting off the Atlantic coast as
weak northern stream flow dips farther south into the Ohio Valley.
As such, afternoon high temperatures will return to the low to mid
90s and more in line with seasonal averages for early July. This
should also keep heat indices in check. In addition, the return of
active northwest flow and moisture return from the Gulf/Atlantic
will support at least scattered to numerous afternoon showers and
storms each day. This will likely be further amplified by several
passing weak shortwave troughs. As with any summer storms, at least
several may become strong to severe with locally damaging winds and
small hail.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Mainly VFR conditions will prevail at all
terminals through the TAF period. A few isolated to widely scattered
showers and thunderstorms will be possible across the mountains this
afternoon. As such, will maintain a PROB30 group at KAVL for
associated thunderstorm restrictions. Otherwise, conditions are
expected to remain quiet outside of the mountains. Another round of
mountain valley fog and low stratus is expected tonight.
Restrictions will once again be possible at KAVL through 01/13z.
Winds will generally be light and variable through the period, but
mainly out of the northeast.

Outlook: Diurnal showers and thunderstorms are expected mainly
across the mountains through the workweek. Mountain valley fog/low
stratus will be possible each morning.

&&

.CLIMATE...
RECORDS FOR 07-02

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1970     65 1943     70 2018     44 1988
                1954
                1931
   KCLT     101 1931     64 1943     76 1991     56 2008
                                        1970
                                        1931
   KGSP     101 1954     66 1943     77 1931     53 1899

RECORDS FOR 07-03

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      93 1970     65 1988     70 2018     50 2008
                1897                    1931        1937
                                                    1932
   KCLT      99 1931     70 1988     76 1925     56 2010
   KGSP      99 2016     70 1988     77 1925     56 1984
                1970
                1953

RECORDS FOR 07-04

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      97 1948     68 1976     70 2016     51 1986
   KCLT      99 1993     70 1968     76 1993     55 1933
                1955
   KGSP     100 1993     70 1988     75 2018     58 2021
                                                    1996
                                                    1933

&&

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

&&

TW