666
FXUS62 KGSP 011726
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
126 PM EDT TUE APR 1 2025
SYNOPSIS
HIGH PRESSURE WILL BRING DRY AND MILD WEATHER TO THE AREA
TODAY. COOLER TEMPERATURES AND RAIN CHANCES ARE IN STORE FOR PARTS
OF THE AREA WEDNESDAY, WITH THE RAIN CHANCES TAPERING OFF LATE
THURSDAY. DRY AND EXCEPTIONALLY WARM WEATHER END THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 1221 PM EDT TUESDAY: IT'S MOSTLY CLEAR ACROSS THE FORECAST
AREA BUT FOR SOME PASSING CIRRUS, AS A RIDGE OF HIGH PRESSURE
CENTERS ITSELF OVER THE APPALACHIANS AND ALLOWS DRY AIR TO SETTLE
ACROSS THE REGION. STILL THINK HIGHS WILL BE A CATEGORY OR SO
ABOVE NORMAL, MAINLY IN THE LOW 70S WITH LIGHT WIND. RH VALUES
ARE EXPECTED TO DIP INTO THE 30-40% RANGE THIS AFTN ACROSS MOST
OF THE AREA, STAYING ABOVE CRITICAL VALUES FOR FIRE WEATHER.
AS OF THE MORNING UPDATE, DEWPOINTS DON'T SHOW SIGNS OF TANKING,
AND THERE'S NOT QUITE ENOUGH DRY AIR ALOFT TO SUPPORT CONCERNS
FOR AN UNEXPECTED DROP.
TONIGHT, THE SFC HIGH WILL QUICKLY SLIDE EAST TO QUEBEC AND NEW
ENGLAND, BRINGING LOW-LEVEL FLOW AROUND OUT OF THE SOUTH. THE NIGHT
SHOULD START OUT CLEAR, BUT UPGLIDE FLOW WILL TAP INTO A LITTLE
ATLANTIC MOISTURE AND SHOULD START PRODUCING LOW CLOUDS ACROSS
THE AREA AFTER MIDNIGHT. FCST SOUNDINGS SHOW SOME ELEVATED CAPE
WITHIN THE UPGLIDE LAYER, AND ALL THE CAMS SHOW SCATTERED LIGHT
SHOWERS BREAKING OUT ACROSS NE GA, THE WESTERN UPSTATE AND INTO
THE SOUTHERN NC MOUNTAINS BEFORE DAYBREAK WEDNESDAY. CONSSHORT
POPS WERE BLENDED IN TO BRING SOME CHC OF SHOWERS MENTIONED BEFORE
THE END OF THE TONIGHT PERIOD. TEMPS WILL FALL INTO THE UPPER 40S
TO LOWER 50S BEFORE THE CLOUDS FORM, THEN STALL OUT, RESULTING IN
LOWS ABOUT 5-10 DEG ABOVE NORMAL.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 130 AM TUE: STRONG HIGH PRESSURE REMAINS CENTERED OFF THE NEW
ENGLAND COAST ON WEDNESDAY. A COMPARATIVELY STRONGER SFC/UPPER LOW
TRACKS THRU THE UPPER MISSISSIPPI VALLEY, WITH RIDGE EXTENDING FROM A
CARIBBEAN ANTICYCLONE NORTH ACROSS THE EASTERN SEABOARD. WAA OVER THE
SFC HIGH SHOULD ALREADY BE UNDERWAY, BUT MOISTURE IS SHOWN TO IMPROVE
AS SECONDARY WARM FRONT SHIFTS NORTHWARD ACROSS THE CWA. THE HIGH
MANAGES TO DRIFT OFFSHORE OVER THE DAY, BUT AT LEAST INITIALLY THE
SETUP FAVORS CAD, AND MAX TEMPS FROM SEVERAL MODELS REFLECT THAT,
DEPICTING A 7-10 DEGREE DROP COMPARED TO THE PREVIOUS DAY ACROSS THE
FOOTHILLS AND NW NC PIEDMONT. 30-50% CHANCES PERSIST OVER MOST LOWER
ELEVATION AREAS NW OF I-85, WITH 50-70% CHANCES ALONG THE SOUTHERN
BLUE RIDGE ESCARPMENT.
THE WAA WEAKENS AS THE SFC LOW TRACKS ACROSS LAKE SUPERIOR INTO
ONTARIO WED NIGHT, AND LOW-LEVEL WINDS VEER. THE LOW WILL HAVE
STARTED TO OCCLUDE BY THEN, AND THE DEEP RIDGE HOLDS OFF THE ADVANCE
OF THE COLD FRONT INTO OUR AREA; IT STALLS AND REVERSES OVER KY AND
WEST TN THURSDAY MORNING. ALTHOUGH THAT SUGGESTS THE FRONT WON'T BE
AVAILABLE TO SCOUR THE CAD, THE PARENT HIGH IS EXPECTED TO BE
FURTHER OFFSHORE BY THAT TIME, AND WITH PRECIP DIMINISHING DURING
THE DAY THU, THE CLOUD DECK SHOULD MIX OUT AND THE WEDGE EFFECTIVELY
SHOULD DISSOLVE WITH IT. MAX TEMPS RISE BACK INTO THE LOWER 80S FOR
MOST AREAS NEAR AND SOUTH OF I-85 OF THE PIEDMONT AND TO NEAR 80 IN
THE FOOTHILLS/NW PIEDMONT AND THE MAJOR MOUNTAIN VALLEYS. OVERNIGHT
TEMPS WILL BE KEPT UP BY MOISTURE ADVECTION AND WEDGE CLOUD COVER
WED NIGHT. ALTHOUGH THE CAD MAY NOT BE A FACTOR THU NIGHT, THE
STRENGTH OF THE RIDGE AND MODEL SUGGESTIONS OF LOW STRATUS
DEVELOPING WITHIN SOUTHERLY FLOW BOTH SUGGEST EXCEPTIONALLY WARM
TEMPS. HIGH-MIN RECORDS COULD BE THREATENED AT SOME OF OUR CLIMATE
SITES BOTH NIGHTS.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 215 AM TUE: ANOMALOUSLY DEEP UPPER ANTICYCLONE REMAINS
VIRTUALLY STATIONARY OVER THE SOUTH ATLANTIC COAST FRI, PEAKING ABOVE
590 DM THAT DAY. A SIMILARLY DEEP TROUGH IS SHOWN OVER THE DESERT
SOUTHWEST, WITH THE STALLED FRONT REMAINING OVER THE OZARKS AND THRU
THE HEART OF THE OHIO RIVER VALLEY. WE WILL REMAIN UNDER A
SOUTHWESTERLY FLOW REGIME BUT WITHOUT LARGE-SCALE FORCING; MECHANICAL
LIFT INTO THE APPALACHIANS WILL BE A FACTOR FRIDAY, WHEN PROFILES
SHOW WEAK ENOUGH CAPPING THAT SOME SHOWERS MAY DEVELOP IN THE UPSLOPE
ZONE. THE RIDGE SHOULD WEAKEN AND DRIFT SLIGHTLY FURTHER EAST SAT,
ALBEIT AFTER ANOTHER DAY OF AIRMASS MODIFICATION. HEIGHTS FALL
SLIGHTLY OVER THE CWA. DESPITE THIS, QPF RESPONSE IS LESSER SAT THAN
FRI ON MOST MODELS, POSSIBLY ON ACCOUNT OF DRYING ALOFT MAKING DEEP
CONVECTION LESS LIKELY. GLOBAL MODELS AND ENSEMBLES DEPICT THE RIDGE
TO BE AROUND 3 SD ABOVE CLIMO, AND PERHAPS UNSURPRISINGLY WE ARE
FORECASTING HIGHS NEAR RECORDS IN OUR CWA FRI-SAT.
A DEEP SHORTWAVE WILL MOVE ACROSS THE NORTHERN PLAINS LATE FRIDAY
INTO SATURDAY AND WILL BE RESPONSIBLE FOR CYCLOGENESIS IN THE OHIO
VALLEY ALONG THE STALLED FRONTAL BOUNDARY. THE SOUTHWEST LOW WILL
SLOWLY DRIFT EAST AND OPEN UP, BEGINNING TO PHASE WITH THE NORTHERN
TROUGH. THE RESULTANT SOUTHERN-STREAM SHORTWAVE APPEARS TO INITIATE
SECONDARY CYCLOGENESIS IN THE OZARKS OR MS DELTA REGIONS, WHICH
ACTIVATES THE BOUNDARY AS A COLD FRONT AND BRINGS IT TO THE SOUTHERN
APPALACHIANS BY THE END OF THE DAY SUNDAY. THE DRY/SUBSIDENT AIRMASS
PRECEDING IT AND RESULTANT WARM TEMPERATURES ALOFT CURRENTLY APPEAR
TO LIMIT INSTABILITY IN MODEL PROGS, BUT THE STRONG GRADIENT BETWEEN
THE TROUGH AND RIDGE RESULT IN 0-3KM SHEAR OF 30-40 KT AND 0-6KM
SHEAR OF 50-70 KT. IF WE HAVE ANY INSTABILITY TO WORK WITH A SEVERE
THREAT COULD DEVELOP SUNDAY AFTERNOON/EVENING. FRONT IS LIKELY TO
PASS SUN NIGHT OR MON MORNING, BRINGING TEMPERATURES BACK TO AROUND
NORMAL, AND POSSIBLY RESULTING IN A FREEZE IN PARTS OF THE MOUNTAINS
MON NIGHT.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: VFR ACROSS THE TERMINAL FORECAST AREA
TODAY AS DRY HIGH PRESSURE DESCENDS OVER THE REGION. A LIGHT
NE WIND CONTINUES AT MANY SITES, BUT SHOULD BECOME SE OVER
THE NEXT FEW HOURS AS THE RIDGE OF HIGH PRESSURE SLIDES EAST.
GENERALLY EXPECT FEW/SKC TO PERSIST THROUGH THE EVENING, AND
THEN BY MIDNIGHT, FOR VFR CEILINGS TO START EXPANDING OVER THE
UPSTATE, AND EVENTUALLY, THE ENTIRETY OF THE WESTERN CAROLINAS.
WINDS WILL BECOME MORE DEFINITIVELY SOUTH THROUGH THE AFTERNOON,
BUT WILL GO BACK EASTERLY OVERNIGHT. MOISTURE WILL SLOWLY BUILD IN
THROUGH THE OVERNIGHT HOURS AND ALLOW SHOWERS TO BREAK OUT SHORTLY
BEFORE DAYBREAK...WITH THE BEST COVERAGE THROUGH THE MORNING HOURS
OVER THE UPSTATE AND BLUE RIDGE ESCARPMENT. SITES IN THE UPSTATE
AS WELL AS KHKY RECEIVED A PROB30 FOR SHRA TO HANDLE THIS...BUT
COVERAGE IS QUESTIONABLE ENOUGH AT KCLT THAT ONLY A VCSH HAS BEEN
ADDED TO THE 18Z TAF.
OUTLOOK: A FEW SCT SHOWERS WITH WIDESPREAD MVFR TO IFR CIGS WILL
LINGER INTO THURSDAY. IFR STRATUS AND FOG MAY SPREAD IN FROM
THE SOUTH THURSDAY NIGHT THRU FRIDAY MORNING. PREDOMINATELY VFR
CONDITIONS EXPECTED FROM FRIDAY THRU THE WEEKEND.
CLIMATE
RECORDS FOR 04-03
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 88 1963 31 1936 64 1946 23 1936
KCLT 90 1946 42 1915 62 1986 26 2021
1946
KGSP 87 1967 44 1901 62 2014 27 2021
1963 1993
1946 1902
RECORDS FOR 04-04
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 83 1999 33 1891 61 1893 22 1936
1978
KCLT 87 1999 43 1911 63 1986 29 1936
1899 1945
1934
KGSP 88 1963 44 1936 62 1999 25 1975
1934
RECORDS FOR 04-05
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 86 1909 30 1891 60 2023 20 1944
1910
KCLT 88 1942 38 1891 62 1910 26 1891
KGSP 90 1934 43 1899 60 2023 25 1904
1888
RECORDS FOR 04-06
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 88 1967 36 1950 64 2023 22 1898
KCLT 90 2010 43 1931 67 2023 28 1891
1929
KGSP 88 2010 47 1950 65 2023 26 1904
1945
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...ARK/MPR
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...MPR
CLIMATE...GSP
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