395
FXUS62 KGSP 180535
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
135 AM EDT FRI JUL 18 2025
SYNOPSIS
DAILY THUNDERSTORM CHANCES CONTINUE THROUGH THE UPCOMING WEEKEND. A
FEW STORMS COULD PRODUCE DAMAGING WIND GUSTS AND LOCALIZED FLASH
FLOODING. HOT AND HUMID CONDITIONS STICK AROUND THROUGH THE FORECAST
PERIOD, WITH A SHORT BREAK POSSIBLE ON TUESDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 1143 PM THURSDAY: BROAD UPPER RIDGING CENTERED JUST OFF THE
SOUTHEAST COAST EXTENDS ACROSS THE DEEP SOUTH AND INTO THE SOUTHERN
PLAINS. FARTHER NORTH, A BELT OF MODEST WESTERLIES IS DRAPED ACROSS
THE NORTHERN TIER ALONG THE CANADIAN BORDER. ANOTHER HOT AND HUMID
SUMMER DAY IS ON TAP BENEATH THE UPPER RIDGE WITH HIGHS A DEGREE OR
TWO WARMER COMPARED TO YESTERDAY. LOW TO MID 90S WILL BE COMMON
OUTSIDE OF THE MOUNTAINS WITH MID TO UPPER 80S IN THE MOUNTAIN
VALLEYS. THE GREATEST OVERLAP BETWEEN HOT TEMPERATURES AND NOTABLE
BOUNDARY LAYER MOISTURE WILL BE ACROSS THE CHARLOTTE METRO WHERE
SEVERAL HOURS OF HEAT INDEX VALUES OF 105-108 DEGREES WILL BE
POSSIBLE. HAVE THUS HOISTED A HEAT ADVISORY HERE FOR THE AFTERNOON
HOURS. SEVERAL RIPPLES WITHIN WEAK FLOW ON THE NORTHERN FLANK OF THE
RIDGE ARE FORECAST TO SLIDE ACROSS KENTUCKY AND INTO THE SOUTHERN
APPALACHIANS. THIS, COMBINED WITH TERRAIN INFLUENCES, SHOULD BE
SUFFICIENT TO INSTIGATE SCATTERED TO NUMEROUS DIURNAL THUNDERSTORMS
ACROSS MUCH OF THE MOUNTAINS, ESPECIALLY ALONG AND NORTH OF I-40.
SOME OF THIS ACTIVITY MAY SLIDE INTO THE ADJACENT NORTH CAROLINA
FOOTHILLS AS WELL. THE I-85 CORRIDOR AND POINTS SOUTH WILL BE
DISPLACED SOUTH OF THE PERTURBED FLOW AND UNDER HIGHER HEIGHTS
CLOSER TO THE UPPER RIDGE. THIS WILL TEND TO LESSEN COVERAGE OF ANY
DIURNAL STORMS TO MAINLY ISOLATED. AS WITH ANY SUMMER THUNDERSTORMS,
A FEW STRONG WET MICROBURSTS WILL BE POSSIBLE, ESPECIALLY WITH ANY
CLUSTERS OF STORMS THAT ARE ABLE TO FORM ALONG COMPOSITE OUTFLOW
BOUNDARIES/COLLISIONS. AN ISOLATED DAMAGING MICROBURST OR TWO CANNOT
BE COMPLETELY DISCOUNTED, BUT A DEARTH OF DCAPE AND VERY MOIST
PROFILES WITH POOR LAPSE RATES WILL GENERALLY PRECLUDE GREATER
MICROBURST POTENTIAL. SPEAKING OF MOIST PROFILES, PWATS OF 1.75-2"
WILL RESULT IN LOCALLY HEAVY RAINFALL WITH ANY SLOW MOVING AND/OR
BACKBUILDING STORMS. LOCALIZED FLASH FLOODING WILL BE POSSIBLE WHERE
2-4" OF RAIN CAN QUICKLY FALL. DIURNALLY DRIVEN STORMS WILL
GRADUALLY WANE IN COVERAGE THROUGH THE EVENING WITH ONLY A COUPLE
STRAY SHOWERS EXPECTED OVERNIGHT.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
AS OF 114 AM EDT FRIDAY: THE MAIN PROBLEM OVER THE UPCOMING WEEKEND
LOOKS LIKE IT WILL BE THE HEAT AND HUMIDITY. EVEN THOUGH THE MODEL
GUIDANCE SEEMS TO SUGGEST SOME POTENTIAL FOR A BREAK ON SATURDAY
AS A PASSING WAVE MOVES PAST JUST TO OUR NORTH AND ORGANIZES ABOVE
NORMAL PRECIP CHANCES ACROSS AT LEAST THE NC PORTION OF THE FORECAST
AREA, THIS MIGHT HAPPEN TOO LATE IN THE DAY TO PREVENT HIGH TEMPS
FROM CLIMBING WELL ABOVE NORMAL. COMBINED WITH RELATIVELY HIGH
DEWPOINTS, THERE'S A GOOD CHANCE THE APPARENT TEMP GETS ABOVE
105F AGAIN ACROSS THE CHARLOTTE METRO AREA...AND ACROSS THE
LAKELANDS...ON SATURDAY AFTERNOON. IF THE FORECAST DOESN'T CHANGE
MUCH, A HEAT ADVISORY WILL BE NEEDED, BUT THERE'S STILL A DECENT
CHANCE THE PRECIP WILL DEVELOP EARLY ENOUGH IN THE DAY TO KEEP
THINGS UNDER ADVISORY CRITERIA. THE CHANCES OF NEEDING A HEAT
ADVISORY EAST OF THE MTNS ARE GREATER ON SUNDAY AFTER THE WAVE
PASSES, BECAUSE THE UPPER RIDGE BUILDS BACK AND A LESS-FAVORABLE
CONVECTIVE ENVIRONMENT MIGHT LIMIT THE COVERAGE OF STORMS. WE WILL
KEEP THE OMNIPRESENT SMALL CHANCE OF WET MICROBURSTS IN PULSE
SEVERE STORM CLUSTERS BOTH DAYS. FLASH FLOODING IS PROBABLY THE
GREATER THREAT GIVEN THE RELATIVELY HIGH PRECIPITABLE WATER BOTH
DAYS, PERHAPS AS HIGH AS 1.75 TO 2 INCHES OVER THE MTNS AND AS
HIGH AS 2.25 INCHES EAST OF THE MTNS, WHICH IS UP AROUND THE 90TH
PERCENTILE. SLOW-MOVING STORMS AND DEEP WARM CLOUD DEPTHS WILL
FAVOR EXCESSIVE RAIN WHERE STORMS REPEAT, SO THIS WILL HAVE TO BE
MONITORED. FOR NOW, THE SLIGHT RISK OF EXCESSIVE RAIN COVERS ONLY
PART OF THE NC MTNS MAINLY NEAR THE TN BORDER.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 130 AM EDT FRIDAY: THE MEDIUM RANGE STARTS OUT INTERESTING FOR
THE EARLY TO MIDDLE PART OF THE WEEK AS THE FLOW PATTERN AMPLIFIES
OVER THE EAST, WITH A PROGRESSIVE NORTHERN STREAM CLOSED LOW
MOVING OVER THE CANADIAN MARITIMES ON MONDAY AND A RIDGE BUILDING
TO OUR WEST. THE RESULTING NW FLOW ALOFT SUGGESTS AN MCS TRACK
THAT WOULD IMPACT OUR AREA AND MAKE MONDAY A MORE ACTIVE DAY AS
A BOUNDARY DROPS DOWN FROM THE NORTH. DEPENDING ON THE TIMING,
THIS COULD KEEP STORMS GOING INTO MONDAY NIGHT. AT THIS POINT,
IT'S TOO EARLY TO SPECULATE ABOUT OUR CHANCES FOR SEVERE WEATHER
OR FLASH FLOOD POTENTIAL, BUT THEY'RE PROBABLY NOT ANY LOWER
THAN WHAT WE WILL HAVE THIS WEEKEND. OTHERWISE, MONDAY WILL BE
ANOTHER SCORCHER WITH ABOVE NORMAL HIGHS AND APPARENT TEMPS THAT
CHALLENGE ADVISORY CRITERIA EAST OF THE MOUNTAINS. BUT, IT COULD
BE THE LAST DAY LIKE THAT BEFORE WE GET A BREAK. TUESDAY HAS THE
HIGHEST UNCERTAINTY AS THE MODEL GUIDANCE MOVES A PROGRESSIVE SFC
HIGH PAST TO OUR NORTH IN A POSITION TO DRIVE THE AFOREMENTIONED
BOUNDARY SOUTH ACROSS THE FCST AREA AND GIVE US A SHOT OF SOMEWHAT
COOLER AND DRIER AIR IN THE AFTERNOON, ESSENTIALLY DROPPING TEMPS
BACK TO NORMAL. ALAS...THE RESPITE WILL BE BRIEF, IF IT HAPPENS AT
ALL, BECAUSE THE HIGH MOVES AWAY AND THE UPPER ANTICYCLONE BUILDS
BACK IN OVERHEAD FROM THE WEST WEDNESDAY AND THURSDAY. THAT MEANS
A WARMING TREND AGAIN WITH TEMPS GETTING BACK UP INTO THE REALM
OF HEAT ADVISORY BY THE END OF THE WEEK. DIURNAL THUNDERSTORMS
WOULD ALSO RETURN.
AVIATION /06Z FRIDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS WILL PREVAIL AT ALL TERMINALS
THROUGH MUCH OF THE TAF PERIOD. MOUNTAIN VALLEY FOG WILL BE POSSIBLE
EARLY THIS MORNING, BUT CONFIDENCE IN FORMATION AT KAVL IS TOO LOW
TO WARRANT MENTION IN THE TAF AT THIS TIME. OTHERWISE, ANOTHER ROUND
OF AFTERNOON/EVENING THUNDERSTORMS IS EXPECTED, ESPECIALLY ACROSS
THE MOUNTAINS WHERE A TEMPO HAS BEEN CARRIED FOR KAVL. ELSEWHERE,
COVERAGE IS EXPECTED TO BE LOWER WITH JUST A PROB30 FOR NOW. AS IS
TYPICALLY THE CASE, BRIEF VISIBILITY AND CEILING RESTRICTIONS CAN BE
EXPECTED WITH ANY STORMS. VFR CONDITIONS WILL RETURN AGAIN OVERNIGHT.
OUTLOOK: THUNDERSTORM CHANCES EACH AFTERNOON/EVENING. LOW STRATUS
OR FOG ARE POSSIBLE EACH MORNING IN MOUNTAIN/RIVER VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...HEAT ADVISORY FROM 2 PM THIS AFTERNOON TO 7 PM EDT THIS
EVENING FOR NCZ071-072-082.
SC...NONE.
SYNOPSIS...PM
NEAR TERM...TW
SHORT TERM...PM
LONG TERM...PM
AVIATION...TW
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