815
FXUS62 KGSP 310750
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
350 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 315 AM MON: 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. A PREFRONTAL BAND OF
CONVECTION EXTENDS FROM WEST VIRGINIA TO NORTHEAST MS AT THIS HOUR.
ALTHOUGH INSTABILITY IS DIMINISHING NOCTURNALLY, A 40+ KT LLJ AND
MCV APPEAR TO STAY WITH THE LINE AND WILL MAINTAIN FAVORABLE SHEAR
PARAMETERS AS THE ACTIVITY PUSHES ACROSS MOST OF TN. PORTIONS OF
THE LINE ARE ALREADY BEGINNING TO LOOK LESS ORGANIZED ON RADAR,
AND CAM CONSENSUS SUGGESTS THIS TREND TO CONTINUE IN EAST TN. OF
INTEREST IS A BOWING SEGMENT OF THE LINE SOUTH OF I-40, ALTHOUGH
THAT TOO APPEARS TO BE WEAKENING. THE LINE IS STILL WORTHY OF 70-80%
POPS AND THUNDER CHANCES IN OUR SMOKIES/BALSAMS BEFORE DAWN. MUCAPE
IS EXPECTED TO BE ONLY A FEW HUNDRED JOULES OVER OUR MOUNTAINS AT
THAT TIME, WHICH SUGGESTS ANY ORGANIZED SEGMENTS STILL HOLDING
TOGETHER ARE UNLIKELY TO SURVIVE EAST OF THE SPINE. A DECAYING
ARC OF SHOWERS HOWEVER COULD PUSH AS FAR EAST AS OUR FOOTHILLS
THROUGH LATE MORNING.
A JET STREAK IS PROGGED TO AMPLIFY OVER THE MID-MS VALLEY EARLY THIS
MORNING. HEIGHT FALLS AT THE BASE OF THE TROUGH OCCUR IN THAT AREA,
ALLOWING SBCAPE TO PERSIST THERE. A NEW LINEAR MCS IS EXPECTED
TO INITIATE AROUND 8-9 AM EST AND TRACK EASTWARD ACROSS GA THRU
MIDDAY. 1000-1500 J/KG OF SBCAPE ARE LIKELY TO DEVELOP IN EASTERN
GA AND THE UPSTATE FROM THEN INTO EARLY AFTN. 0-6KM SHEAR WILL
PEAK AROUND 60 KT, WITH 0-3KM AROUND 40 KT. THE MCS APPEARS LIKELY
TO STRENGTHEN AND BE MAINTAINED THROUGH THOSE AREAS, 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. THE
05-06Z HRRRS, DEPICTING LESS CONVECTION CROSSING THE SMOKIES,
INSTEAD DEPICT CELLS TRACKING FROM NEAR THE TN/AL BORDER TO
WESTERN NC BETWEEN NOW AND ABOUT NOON, BY WHICH TIME FAVORABLE
INSTABILITY/SHEAR ALLOW THEM TO ORGANIZE AND PROGRESS ACROSS OUR
NC ZONES. THIS IS MORE LIKE WHAT EARLIER RUNS HAD SHOWN. SO,
THE DISPOSITION OF THE MORNING ACTIVITY APPEARS CRITICAL FOR
DETERMINING OUR SEVERE THREAT, AND WE MAY HAVE TWO DISTINCT ROUNDS
PERHAPS AFFECTING DISTINCT AREAS. 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,
06Z HRRR DEPICTS A ZONE OF STRONGER AND MORE PERSISTENT UPDRAFT
HELICITY ALONG THE NORTHERN TIER OF SC 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 /08Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: MOSTLY IFR CIGS OVER THE PIEDMONT AT
ISSUANCE TIME, WITH A FEW POCKETS OF MVFR COMING AND GOING
WITHIN. NOT EXPECTING MUCH CHANGE IN THIS DECK THROUGH DAYBREAK,
ALTHOUGH IFR IS LIKELY TO BECOME MORE COMMON AND LIFR DEVELOPING IN
SPOTS. KAVL WILL SEE PREDOMINANTLY MVFR. -DZ OR A FEW -SHRA WILL
BE POSSIBLE PRIOR TO DAYBREAK BUT WITH LITTLE ADDITIONAL IMPACT
BEYOND THE RESTRICTIVE CIGS. AHEAD OF AN APPROACHING COLD FRONT,
A LINE OF TSRA WILL MOVE ACROSS TN THRU ABOUT 09Z THIS MORNING,
THEN LIKELY PUSHING INTO THE NC MOUNTAINS AND WEAKENING. PROB30
AT KAVL AND TEMPO AT KHKY FOR THIS ACTIVITY. CIGS WILL SLOWLY LIFT
THRU THE EARLY DAY. 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 1-1.5" 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...WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
CLIMATE...ARK
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