896
FXUS62 KGSP 011759
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
159 PM EDT WED JUL 1 2026
WHAT HAS CHANGED
CONFIDENCE CONTINUES TO INCREASE IN DANGEROUS HEAT THURSDAY THROUGH
AT LEAST SATURDAY. A HEAT ADVISORY HAS BEEN ISSUED FOR PORTIONS OF
THE AREA FOR THURSDAY AND ADDITIONAL ADVISORIES WILL LIKELY BE
NEEDED THROUGH THE WEEKEND.
UPDATED THE AVIATION DISCUSSION FOR THE 18Z TAFS.
KEY MESSAGES
1. DANGEROUS HEAT CONTINUES TO BUILD THROUGH THE WEEK AND INTO THE
HOLIDAY WEEKEND, WITH HEAT INDICES LIKELY EXCEEDING 105 DEGREES
ACROSS MUCH OF THE PIEDMONT AND FOOTHILLS. 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: DANGEROUS HEAT CONTINUES TO BUILD THROUGH THE WEEK AND
INTO THE HOLIDAY WEEKEND, WITH HEAT INDICES LIKELY EXCEEDING 105
DEGREES ACROSS MUCH OF THE PIEDMONT AND FOOTHILLS. DAILY
THUNDERSTORMS WILL ALSO BE POSSIBLE ACROSS THE MOUNTAINS.
A DIGGING WESTERN TROUGH EXTENDING FROM THE PACIFIC NORTHWEST
THROUGH THE GREAT BASIN CONTINUES TO FURTHER STRENGTHEN A HIGHLY
ANOMALOUS UPPER RIDGE OVER THE TENNESSEE VALLEY. THE RIDGE WILL
SLOWLY MIGRATE EAST ACROSS THE SOUTHERN APPALACHIANS AND INTO THE
COASTAL PLAIN TOMORROW THROUGH AT LEAST SATURDAY. 850MB TEMPERATURES
ARE FORECAST TO RISE INTO THE 24-26 C RANGE, WHICH IS ABOVE THE 99TH
PERCENTILE FOR EARLY JULY. THIS ANOMALOUS WARMTH WILL FOSTER VERY
HOT HIGH TEMPERATURES IN THE UPPER 90S TO LOW 100S TOMORROW THROUGH
AT LEAST SATURDAY. SOME LOCATIONS ACROSS THE PIEDMONT MAY SEE AIR
TEMPERATURES PEAK AS HIGH AS 102-104 DEGREES. MOUNTAIN VALLEYS WILL
BE HOT AS WELL WITH TEMPERATURES RISING INTO THE LOW TO MID 90S WITH
THE ONLY RELIEF FOUND AT THE VERY HIGHEST MOUNTAIN TOPS WHERE HIGHS
WILL BE IN THE LOW 80S.
THE BIGGEST QUESTION THAT REMAINS IS HOW MUCH MOISTURE MIXES OUT AND
RESULTING IMPLICATIONS ON HEAT INDICES. FORECAST SOUNDINGS CONTINUE
TO DEPICT A DRY AND DEEPLY MIXED BOUNDARY LAYER EXTENDING TO AT
LEAST 700MB, IF NOT HIGHER. SURFACE DEWPOINTS MIX OUT INTO THE UPPER
50S TO LOW 60S, WHICH WOULD HELP TO KEEP HEAT INDEX VALUES IN CHECK.
THIS IS A MORE AGGRESSIVE SOLUTION, HOWEVER, AND CURRENT
OBSERVATIONS TODAY SHOW NOTABLY MORE BOUNDARY LAYER MOISTURE HANGING
ON ACROSS THE AREA. FORECAST DEWPOINTS TOMORROW THROUGH THE WEEKEND
WERE BLENDED DOWN WITH PART RAW MODEL GUIDANCE, BUT EVEN THESE LOWER
VALUES STILL SUPPORT HEAT ADVISORY CRITERIA ACROSS THE CHARLOTTE
METRO AREA INTO THE I-40 CORRIDOR AND PORTIONS OF THE SAVANNAH RIVER
VALLEY IN NORTHEAST GEORGIA. AS SUCH, A HEAT ADVISORY HAS BEEN
ISSUED FOR THESE AREAS FROM NOON TO 8PM TOMORROW. ADDITIONAL HEAT
ADVISORIES WILL LIKELY BE NEEDED THROUGH THE REST OF THE HOLIDAY
WEEKEND. PRECAUTIONS SHOULD BE TAKEN IF SPENDING TIME OUTDOORS AS
THIS HEAT WILL BE DANGEROUS WITH QUICK ONSET OF HEAT ILLNESS.
ADDITIONALLY, AFTERNOON THUNDERSTORMS WILL BE POSSIBLE ACROSS THE
MOUNTAINS EACH DAY. THE ENVIRONMENT WILL BE FAVORABLE FOR ANY STORMS
THAT DEVELOP TO BECOME SEVERE. THIS AFTERNOON'S ENVIRONMENT IS
RATHER HIGH END WITH OVER 5000 J/KG OF SURFACE-BASED CAPE, STEEP LOW-
LEVEL LAPSE RATES AND LARGE DCAPE. ANY DEEPER STORMS WILL BE CAPABLE
OF DAMAGING WINDS AND LARGE HAIL. FORECAST CONFIDENCE IS LOWER,
HOWEVER, IN REGARDS TO COVERAGE WITH GUIDANCE HAVING A HARD TIME
DEPICTING FORCING MECHANISMS AND HOW MUCH WILL GET GOING. THIS
PATTERN WILL REPEAT THE NEXT SEVERAL DAYS WITH ACTIVITY MAINLY
CONFINED TO THE MOUNTAINS. AN ISOLATED STORM CANNOT BE RULED OUT
INTO THE FOOTHILLS, BUT IS MUCH LESS CERTAIN.
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 WEAKENS AND SHIFTS OFFSHORE WITH
SOUTH/SOUTHEASTERLY RETURN FLOW FROM THE GULF/ATLANTIC. 850MB
TEMPERATURES WILL STILL BE RATHER WARM AND COULD SUPPORT ANOTHER DAY
OF DANGEROUS HEAT INTO SUNDAY, BUT IT WILL BE HIGHLY DEPENDENT ON
CLOUD COVER AND POTENTIAL FOR GREATER COVERAGE OF AFTERNOON
THUNDERSTORMS. PERTURBED NORTHERN STREAM FLOW IS PROGGED TO SAG INTO
THE OHIO VALLEY WITH EMBEDDED SHORTWAVE PERTURBATIONS PASSING NEAR
THE AREA, INCLUDING A MORE WELL DEFINED SHORTWAVE TROUGH AROUND
TUESDAY/WEDNESDAY. THIS WILL SUPPORT A RETURN TO A MORE TYPICAL
SUMMER PATTERN WITH SEASONABLE TEMPERATURES IN THE LOW 90S AND DAILY
THUNDERSTORMS ACROSS THE REGION. AS WITH ANY SUMMER STORMS, AT LEAST
SOME OF THESE MAY BECOME SEVERE WITH DAMAGING WINDS AND SMALL HAIL.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS ARE EXPECTED TO PREVAIL AT
MOST TERMINALS THROUGH THE TAF PERIOD. AN AFTERNOON CUMULUS FIELD
HAS DEVELOPED ACROSS MUCH OF THE AREA, BUT CLOUD BASES ARE EXPECTED
TO REMAIN HIGH ENOUGH TO NOT RESULT IN ANY RESTRICTIONS. ISOLATED TO
WIDELY SCATTERED AFTERNOON THUNDERSTORMS ARE POSSIBLE MAINLY ACROSS
THE MOUNTAINS WITH A PROB30 GROUP MAINTAINED AT KAVL. HEADING INTO
TONIGHT, THE MAIN FOCUS WILL ONCE AGAIN SHIFT TO MOUNTAIN VALLEY FOG
AND LOW STRATUS. THE SETUP DOESN'T QUITE LOOK AS IDEAL AS THIS
MORNING, BUT AT LEAST SOME DEGREE OF VISIBILITY AND CEILING
RESTRICTIONS CAN BE EXPECTED. ANY FOG SHOULD QUICKLY MIX OUT AFTER
SUNRISE WITH ANOTHER CUMULUS FIELD DEVELOPING THROUGH THE LATE
MORNING HOURS.
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...HEAT ADVISORY FROM NOON TO 8 PM EDT THURSDAY FOR GAZ026-028-
029.
NC...HEAT ADVISORY FROM NOON TO 8 PM EDT THURSDAY FOR NCZ036-037-
056-057-069>072-082.
SC...NONE.
TW
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