579
FXUS62 KGSP 300520
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
120 AM EDT MON JUN 30 2025
SYNOPSIS
A TYPICAL SUMMER PATTERN CONTINUES WITH SEASONABLE TEMPERATURES AND
CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS. A COLD FRONT
APPROACHES THE AREA TUESDAY WITH A CHANCE FOR STRONGER
THUNDERSTORMS. BEHIND THE FRONT, DRIER WEATHER RETURNS FOR THE
HOLIDAY WEEKEND.
NEAR TERM /THROUGH TODAY/
AS OF 1230 AM EDT MONDAY:NO CHANGES TO THE FORECAST AT THIS TIME AS
EVERYTHING IS ON TRACK. A SMALL STORM IS STILL STRUGGLING TO STAY
ALIVE IN DAVIE COUNTY, BUT IS NOT EVEN PRODUCING LIGHTNING AT THIS
TIME. SHOULD CLEAR IN THE NEXT HOUR. CALM TO LIGHT WINDS ACROSS MOST
OF THE CWA. ALL IS QUIET ON THE WESTERN FRONT.
EXPECT CLEARING SKIES AND LIGHT WINDS OVERNIGHT. MOUNTAIN VALLEY
FOG IS LIKELY WITH PATCHY FOG ELSEWHERE, ESPECIALLY NEAR BODIES
OF WATER OR LOCATIONS THAT HAD HEAVIER RAINFALL. AT THIS UPDATE,
SAW FIT TO INCLUDE A MENTION OF FOG NEAR CLEMSON AND LIBERTY WHERE
HEAVY SHOWERS MOVED IN LATE IN THE DAY, AND FOG IS CLIMATOLOGICALLY
MORE FAVORED. ELSEWHERE CONFIDENCE TOO LOW TO PUT IN A MENTION
AT THIS TIME. LOWS NEAR NORMAL MOUNTAINS AND A FEW DEGREES ABOVE
NORMAL ELSEWHERE.
MONDAY LOOKS TO BE A NEAR CARBON COPY WITH GOOD COVERAGE OF
CONVECTION DEVELOPING ACROSS THE MOUNTAINS AROUND NOON AND SCATTERED
CONVECTION ELSEWHERE. EXPECT A NEAR CARBON COPY WITH THE SEVERE
DOWNBURST AND HEAVY RAIN POTENTIAL WITH A VERY UNSTABLE AIR MASS,
LIGHT BULK SHEAR, MODERATE DCAPE, AND HIGH PW VALUES. HIGHS ACROSS
THE MOUNTAINS WILL BE NEAR NORMAL AND A FEW DEGREES ABOVE NORMAL
ELSEWHERE.
SHORT TERM /TONIGHT THROUGH WEDNESDAY/
AS OF 1225 PM SUNDAY: A NORTHERN STREAM TROUGH WILL SWING ACROSS THE
GREAT LAKES REGION AND INTO NEW ENGLAND ON TUESDAY WHILE ANOTHER
UPPER LOW ASSOCIATED WITH A TROPICAL UPPER TROPOSPHERIC TROUGH
DRIFTS ALONG THE SOUTHEAST COAST. BROAD BERMUDA RIDGE WILL ALSO
EXTEND INTO THE COASTAL PLAIN WHICH WILL FURTHER PROMOTE DEEP-LAYER
SOUTHWEST FLOW ACROSS THE REGION. PLENTIFUL DEEP MOISTURE WILL BE
PRESENT WITHIN THIS REGIME WITH A SURFACE COLD FRONT APPROACHING THE
AREA FROM THE NORTHWEST WITHIN THE TROUGH AXIS. MOISTURE POOLING
AHEAD OF THE FRONTAL BOUNDARY IN CONCERT WITH WEAK, BUT NON-ZERO,
FORCING WILL PROMOTE NUMEROUS TO WIDESPREAD MAINLY DIURNAL
THUNDERSTORMS ACROSS THE AREA ON TUESDAY. WEAK TROUGHING AND THE
NEARBY POSITION OF THE FRONT MAY EVEN SUPPORT SEVERAL STORMS
CONTINUING INTO THE OVERNIGHT BEYOND THE TRADITIONAL DIURNAL
PATTERN. FORECAST SOUNDINGS REVEAL TRADITIONAL SUMMER PROFILES IN
THE SOUTHEAST WITH VERY TALL/SKINNY CAPE AND A LACK OF DRIER AIR.
THE RESULT IS POOR LAPSE RATES, WEAK DCAPE AND A LOWER SURFACE DELTA
THETAE. CLUSTERS OF STORMS AND/OR LINEAR SEGMENTS WILL LIKELY
ORGANIZE ALONG COMPOSITE COLD POOLS AND A COUPLE STRONG TO ISOLATED
SEVERE STORMS CANNOT BE RULED OUT WITH THE MAIN THREAT BEING
ISOLATED WET MICROBURSTS. THE BOUNDARY ITSELF SLOWLY DROPS INTO THE
AREA TUESDAY NIGHT INTO WEDNESDAY WITH ANOTHER ROUND OF DIURNAL
SHOWERS AND STORMS WEDNESDAY AFTERNOON AND EARLY EVENING.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 1245 PM SUNDAY: A SECOND SHORTWAVE TROUGH DROPS ACROSS THE
GREAT LAKES THURSDAY WITH WEAK NORTHWEST FLOW SETTING UP OVER THE
SOUTHERN APPALACHIANS IN THE WAKE OF THE FIRST TROUGH AXIS. THIS
SHOULD HELP TO SLOWLY PUSH THE FRONTAL BOUNDARY ACROSS AND
EVENTUALLY SOUTH OF THE AREA. HOW LONG THIS TAKES AND EXACTLY HOW
FAR SOUTH IT ENDS UP REMAINS TO BE SEEN. IF PROGRESS IS SLOWER AT
LEAST ISOLATED TO WIDELY SCATTERED DIURNAL STORMS WILL REMAIN
POSSIBLE ACROSS SOUTHERN PORTIONS OF THE AREA ON THURSDAY AND
POTENTIALLY FRIDAY. MOST OF THE AREA SHOULD SEE THE ARRIVAL OF DRIER
AIR, HOWEVER, WITH PWATS FALLING TO 1-1.25" WITHIN LOWER THETAE AIR.
HISTORICALLY, PWATS THIS LOW ARE UNFAVORABLE FOR SUMMER DIURNAL
PULSE CONVECTION ALTHOUGH AN ISOLATED STORM OR TWO CAN NEVER BE
RULED OUT ACROSS THE MOUNTAINS. RELATIVELY DRY WEATHER MAY CONTINUE
THROUGH THE HOLIDAY WEEKEND, BUT DEEPER MOISTURE WILL EVENTUALLY
RETURN AND IT'S ARRIVAL WILL BE TIED TO AN INCREASE IN RAIN CHANCES -
WHENEVER THAT ENDS UP OCCURRING.
AVIATION /05Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD
AT MOST SITES. SIMILAR TO THE LAST FEW DAYS, WINDS REMAIN CALM/VRB
OVERNIGHT. HIGHER MOISTURE IN THE REGION IS INCREASING THE
DEVELOPMENT OF PATCHY BR/FG ACROSS THE AREA. CONFIDENCE IS NOT HIGH
ENOUGH AT PREVAIL AT THE TYPICAL MOUNTAIN SITES, BUT BE AWARE THAT
PASSING BR COULD DEVELOP ANYWHERE. SHOULD START TO SLOWLY CLEAR UP
AFTER DAYBREAK. WILL KEEP TEMPOS AT KAVL/KHKY FOR BR. MONDAY LOOKS
TO BE MUCH OF THE SAME. SOUTHERLY WINDS PICK UP BY MID MORNING AND
INTO THE AFTERNOON TIMEFRAME, BUT STILL REMAINS LIGHT. THERE COULD
BE A FEW VERY LOW-END GUSTS OVER KCLT DURING THE AFTERNOON, BUT
WOULD REMAIN LESS THAN 15KTS. THE AFTERNOON BRINGS ANOTHER CHANCE
FOR SCATTERED SHOWERS AND TSRA, POSSIBLE ANYWHERE ESPECIALLY IN THE
MOUNTAINS. CHANCES ARE HIGHER FOR PORTIONS OF THE MOUNTAINS SO WILL
ADD A TEMPO AT KAVL, WITH PROB30S ELSEWHERE. ONCE SHOWERS AND
THUNDERSTORMS CLEAR UP, ANOTHER CALM NIGHT AHEAD. DEPENDING ON
WHETHER OR NOT THE MOUNTAIN SITES CAN RECEIVE ANY RAIN, WILL GREATLY
IMPACT THE BR/FG CHANCES BEFORE THE END OF THE TAF PERIOD.
OUTLOOK: DAILY CHANCES FOR AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS INTO AT LEAST MIDWEEK. FOG AND/OR LOW STRATUS POSSIBLE
EACH MORNING IN THE USUAL MOUNTAIN VALLEYS AS WELL AS NEAR LAKES AND
RIVERS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CP
NEAR TERM...CP/RWH/WIMBERLEY
SHORT TERM...TW
LONG TERM...TW
AVIATION...CP
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