807
FXUS62 KGSP 311505
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1105 AM EDT MON MAR 31 2025
SYNOPSIS
SHOWER AND THUNDERSTORM ARE EXPECTED TO CROSS THE AREA TODAY
AHEAD OF AN APPROACHING COLD FRONT. A FEW OF THESE STORMS COULD
BE SEVERE. THE FRONT PUSHES THRU TONIGHT, AND USHERS IN DRY HIGH
PRESSURE FOR TUESDAY. THE HIGH WILL SETTLE OFF THE SOUTHEAST
COAST AND KEEP WARM SOUTHERLY FLOW ACROSS THE REGION, RESULTING
IN WELL-ABOVE-NORMAL TEMPERATURES THROUGH THE END OF THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 1055 AM MON: MORNING CONVECTION HAS LEFT BEHIND A COOL POOL
OF SORTS ACROSS THE MTNS, BUT ALSO A FEW THIN SPOTS IN THE OVERCAST
TO ALLOW FOR HEATING. MEANWHILE, THE SPC MESOANALYSIS SHOWS A SLOW
DESTABILIZATION UNDERWAY NORTHWARD ACROSS GA INTO WESTERN SC SOUTH
OF THE OUTFLOW FROM THE MORNING REMNANT CONVECTION ACROSS THE NC
MOUNTAINS. STILL PLENTY OF INDICATION THAT A PLUME OF AT LEAST
1000 J/KG WILL DEVELOP NORTHWARD AHEAD OF THE CONVECTION MAINLY
EAST OF THE MTNS INTO THE AFTERNOON, SO ADDITIONAL THUNDERSTORMS
ARE STILL A SAFE BET. THE SEVERITY OF THOSE STORMS IS THE BIG
QUESTION, AND WE AWAIT A MORE COMPLETE LOOK AT THE 12Z HREF TO
COMMENT FURTHER. AS OF NOW, THE LATEST HRRR DOES NOT LOOK ALL THAT
SCARY, AND THE CONVECTION TO THE WEST WAS ON A TYPICAL WEAKENING
TREND. BUT, WE SHALL SEE HOW IT EVOLVES WHEN WE COME OUT OF THE
DIURNAL MINIMUM OVER THE NEXT HOUR OR TWO AND IT COMES EAST ACROSS
GA. THINK A WATCH CAN BE ANTICIPATED OVER MOST OF OUR GA/SC ZONES
AND PROBABLY INTO METRO CLT AT SOME POINT, JUST THE SAME.
OTHERWISE...A MATURE SFC LOW WILL TRACK ACROSS SOUTHERN
ONTARIO/QUEBEC THRU THIS AFTERNOON, PULLING A COLD FRONT ACROSS
THE OHIO VALLEY OVER THE COURSE OF THE DAY. AN MCS APPEARS LIKELY
TO STRENGTHEN AND BE MAINTAINED ACROSS THE DEEP SOUTH, AND THIS
IS BACKED UP BY CAM CONSENSUS SHOWING CONVECTION PROGRESSING
ACROSS OUR SOUTHERN HALF IN MID TO LATE AFTERNOON. FURTHER NORTH
INSTABILITY MAY BE MORE LIMITED, AND IN PARTICULAR SOME EARLIER
HRRR RUNS SEEMED TO SUGGEST THE COLD POOL FROM THE DECAYED
EARLY MORNING MCS WOULD HAVE A STABILIZING EFFECT IN THE NC
MOUNTAINS/FOOTHILLS. DAMAGING WINDS--POSSIBLY FROM A LINEAR OR
BOWING SEGMENT WITH EMBEDDED SUPERCELL STRUCTURES--WOULD BE THE
PRIMARY THREAT TODAY, ALTHOUGH ENOUGH INSTABILITY WILL BE PRESENT
FOR HAIL WITH ANY SUPERCELLS. LOW-LEVEL PARAMETERS SUPPORT A
TORNADO THREAT AS WELL ALTHOUGH SOMEWHAT MORE MARGINAL. OF NOTE,
EARLIER HRRR RUNS DEPICTED A ZONE OF STRONGER AND MORE PERSISTENT
UPDRAFT HELICITY ALONG THE NORTHERN TIER OF SC AND ACROSS THE
WESTERN PIEDMONT AROUND 22Z-00Z, MAYBE AS THE OUTFLOW FROM THE NC
LINE IS ENCOUNTERED BY ROTATING ELEMENTS OF THE SOUTHERN LINE. SPC
RETAINED ENHANCED RISK ON THE DAY 1, TRIMMED BACK SLIGHTLY TO THE
PIEDMONT, WITH SLIGHT RISK STILL OVER THE MOUNTAINS.
SOME SHOWERS APPEAR LIKELY TO REDEVELOP BEHIND THE PRIMARY LINE
OF CONVECTION CLOSER TO THE SFC FRONT LATER IN THE AFTERNOON OR
EVENING, BUT THE SEVERE THREAT WILL PROBABLY DROP OFF AFTER THE
SOUTHERN LINE EXITS, MOST LIKELY BY 00Z. NW FLOW SHOWERS ALSO
MAY DEVELOP ONCE WIND SHIFT OCCURS IN THE MOUNTAINS. TEMPS ARE
EXPECTED TO REMAIN ABOVE FREEZING THERE, EXCEPT POSSIBLY IN THE
HIGHEST ELEVATIONS AFTER PRECIP DIMINISHES NEAR DAYBREAK TUE. MINS
WILL REMAIN A FEW DEGREES ABOVE NORMAL.
SHORT TERM /TUESDAY THROUGH WEDNESDAY/
KEY MESSAGES:
1) DRY WEATHER RETURNS TUESDAY.
2) A CHANCE OF SHOWERS AND ABOVE-NORMAL TEMPERATURES WEDNESDAY.
AS OF 210 AM MONDAY: AN AXIS OF SFC HIGH PRES EXTENDING FROM
ONTARIO WILL CROSS THE FORECAST AREA TUESDAY UNDER BUILDING HEIGHTS
ALOFT. THE AIR MASS WILL BE FAIRLY DRY, WITH AFTN RH RETURNING
TO THE 25-35% RANGE FOR MUCH OF THE AREA. TEMPS WILL BE ABOUT 5-8
DEG ABOVE NORMAL WITH LIGHT WIND AND SUNNY SKIES.
THE HIGH WILL SHIFT EAST TO QUEBEC AND NEW ENGLAND, WITH A
WEDGE-LIKE RIDGE EXTENDING SOUTH INTO THE CAROLINAS TUESDAY NIGHT
INTO WEDNESDAY. GUIDANCE AGREES THAT SOUTHERLY FLOW ATOP THE
WEDGE MAY PRODUCE WIDESPREAD STRATUS BY DAYBREAK WEDNESDAY, WITH
SOME ELEVATED INSTABILITY TO SUPPORT SCATTERED SHOWERS THRU THE
DAY. THE HIGH WILL BE TRANSIENT, AND THE SHOWERY NATURE OF PRECIP
SHOULD RESULT IN THE WEDGE STRUGGLING TO HOLD THRU THE DAY. WITH
THAT SAID, THE 00Z GUIDANCE HAS TRENDED COOLER ON TEMPS, ESPECIALLY
NEAR THE ESCARPMENT. THE NBM MAY BE STRUGGLING WITH THIS AND LOOKS
A BIT TOO WARM. SO BLENDED IN THE CONSALL FOR HIGHS WEDNESDAY. THE
ELEVATED CAPE MAY BE ENOUGH FOR ISOLATED GENERAL THUNDERSTORMS,
ESPECIALLY NEAR THE WEDGE FRONT. THE FRONT WILL BEGIN TO LIFT NORTH
AND MAY PRODUCE ADDITIONAL SHOWERS WEDNESDAY NIGHT. LOWS WILL BE
SEVERAL DEG ABOVE NORMAL UNDER CLOUDY TO MOSTLY CLOUDY SKIES.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
KEY MESSAGES
1) GENERALLY DRY WEATHER THRU SATURDAY, AS A STRONG RIDGE BUILDS
ACROSS THE SOUTHEAST
2) TEMPERATURES WARM TO NEAR RECORD HIGHS FRIDAY AND SATURDAY.
3) RAIN CHANCES MAY RETURN SUNDAY WITH AN APPROACHING COLD FRONT.
AS OF 250 AM MONDAY: A STRONG UPPER RIDGE WILL BUILD ACROSS
THE SOUTHEAST THURSDSAY THRU SATURDAY, WITH A POTENTIAL 594 DAM
RIDGE AT 500 MB JUST EAST OF FL. THIS RIDGE WILL KEEP A FRONT
AND ASSOCIATED MOISTURE LARGELY WEST AN DNORTH OF THE FORECAST
AREA DURING THIS PERIOD. HAVE OPTED TO GO WITH THE 6-HOURLY NBM
POPS, WHICH ARE LOWER THAN THE REGULAR NBM, GIVEN THE EXPECTED
SUPPRESSING EFFECTS OF THE HIGH. WITH THAT SAID, ENOUGH HUMIDITY
MAY BE PRESENT FOR SOME DIURNAL INSTABILITY AND ISOLATED TO WIDELY
SCATTERED SHOWERS THURSDAY, WITH THESE POPS BEING SHUNTED NORTH TO
NEAR THE TN BORDER FRIDAY AND SATURDAY. HIGHS WILL LIKELY BE IN THE
LOW TO MID 80S THURSDAY, AND MID TO UPPER 80S FRIDAY AND SATURDAY
(POSSIBLY 90 AROUND CHARLOTTE). THESE WILL BE NEAR RECORD HIGHS
FOR ALL THREE OF OUR CLIMATE SITES (SEE CLIMATE SECTION BELOW).
IT MAY BE OPTIMISTIC, BUT THE 00Z GUIDANCE HAS COME IN SHOWING
THE RIDGE BEGINNING TO BREAK DOWN SUNDAY, ALLOWING TEMPS TO NOT
BE QUITE AS WARM AND ALSO BRINGING SOME RAIN CHANCES BACK INTO
THE FORECAST AREA. A LOW PRESSURE SYSTEM WILL TRACK ACROSS THE
SOUTHERN GREAT LAKES AND MAY BRING A COLD FRONT THRU THE AREA
SUNDAY OR SUNDAY NIGHT. POPS RAMP UP TO SOLID CHC TO LOW-END LIKELY.
AVIATION /15Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: MOSTLY IFR CIGS OVER THE PIEDMONT AT
11Z. KAVL WILL SEE PREDOMINANTLY MVFR. AHEAD OF AN APPROACHING COLD
FRONT, A LINE OF DECAYING TSRA WILL BE NEAR KAVL IN THE FIRST COUPLE
HRS OF THE PERIOD AND SOME SHRA COULD SURVIVE TO KHKY. PROB30 AT
KAVL AND VCSH AT KHKY FOR THIS ACTIVITY. CIGS WILL SLOWLY LIFT LATE
MORNING TO MIDDAY. A SECOND BAND OF TSRA WILL DEVELOP IN AL/GA BY
LATE MORNING AND WILL PROPAGATE INTO WESTERN NC/SC BY EARLY AFTN,
PROMPTING TEMPOS AT ALL SITES FOR TSRA AND MVFR TO IFR VSBY/CIGS. A
RISK OF DAMAGING WINDS AND POSSIBLY 1-2" HAIL WILL ACCOMPANY THESE
STORMS. A FEW SHRA MAY REDEVELOP FOLLOWING THE TSRA WITH LESSER
IMPACTS. WINDS WILL BE GUSTY 15-25 KT FROM THE SSW TO SW UNTIL EARLY
EVENING, THEN SHIFT TO NW WITH PASSAGE OF FRONT. REDEVELOPMENT OF
MVFR CIG CAN'T BE RULED OUT AT KAVL AFTER 06Z.
OUTLOOK: DRYING AND VFR EXPECTED ON TUESDAY. SMALL CHANCE OF
SHOWERS AND ASSOCIATED RESTRICTIONS WEDNESDAY AND THURSDAY.
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...ARK
NEAR TERM...PM/WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
CLIMATE...
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