222
FXUS62 KGSP 301057
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
657 AM EDT SUN MAR 30 2025
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES INCREASE TODAY AS COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL CROSS THE AREA MONDAY,
BRINGING THE POTENTIAL FOR STRONG TO SEVERE STORMS. DRY HIGH
PRESSURE RETURNS TUESDAY, THEN BECOMES ESTABLISHED OFF THE EAST
COAST, RESULTING IN WELL ABOVE NORMAL TEMPERATURES ACROSS THE
REGION LATE IN THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 645 AM: EXPANSIVE HIGH PRESSURE REMAINS OVER THE WESTERN
ATLANTIC. MEANWHILE A SLOWLY STRENGTHENING SFC LOW AND ATTENDANT
SHORTWAVE WILL MOVE INTO THE UPPER MISSISSIPPI VALLEY, ON TRACK TO
PASS BY WELL TO OUR NORTHWEST. OUR CWA AND POINTS SOUTH WILL BE
MORE OR LESS IN THE WARM SECTOR OF THE LOW THROUGH THE NEAR TERM
PERIOD AND INTO MONDAY, FOR THAT MATTER. VERY LITTLE IN THE WAY OF
DYNAMIC FORCING WILL BE AT WORK IN OUR AREA THIS MORNING. WEAK WARM
UPGLIDE IS ONGOING. THE BETTER MOISTURE/FORCING WILL REMAIN WEST OF
THE MOUNTAINS THIS MORNING BUT A FEW SHOWERS ARE POSSIBLE INITIALLY
OVER THE MOUNTAINS, WITH CHANCES SLOWLY EXPANDING EAST THROUGH
EARLY AFTERNOON. TODAY WILL BE GENERALLY CLOUDY. MAX TEMPS WILL
BE COOLER THIS AFTERNOON ON THAT NOTE AND WITH REDUCED THICKNESSES
OWING TO FALLING HEIGHTS, BUT STILL SEVERAL DEGREES ABOVE NORMAL.
INSTABILITY WILL DEVELOP DIURNALLY, LIKELY TO THE TUNE OF 100-500
J/KG SBCAPE, PERHAPS EVEN HIGHER. DEWPOINTS RISE INTO THE UPPER
50S TO NEAR 60 IN THE PIEDMONT. AS THE LOW MOVES TOWARD THE GREAT
LAKES AND MAKES ITS NEAREST PASS TO THE AREA, UPGLIDE APPEARS TO
STRENGTHEN OVER THE CWA, IN WHAT MIGHT BE TERMED A SECONDARY WARM
FRONT. THESE TWO ASPECTS APPEAR KEY FOR POPS TO INCREASE EAST OF
THE MOUNTAINS. MOST CAMS DEPICT SHOWERS DEVELOPING/TRACKING FROM
SW TO NE ACROSS THE CWA FROM AFTERNOON THRU EVENING; SLOWED ONSET
A BIT PER RECENT TRENDS IN 06Z CYCLE GUIDANCE. LIKELY WORDING IS
INCLUDED IN MOST AREAS WEST OF US 221 BY LATE AFTERNOON, AND TO
30-50% IN AREAS EAST. SEVERE WEATHER IS NOT ANTICIPATED DUE TO
LACK OF DRY AIR ALOFT AND WITH SHEAR UNREMARKABLE.
THE MECHANICAL LIFT PEAKS AS FLOW AMPLIFIES THIS EVENING BEFORE
VEERING TO A LESS FAVORABLE DIRECTION FOR OUR EASTERN ESCARPMENT
WITH THE APPROACH OF THE TROUGH, BUT UPGLIDE WILL CONTINUE. POPS
TREND DOWN IN THE EAST BUT REMAIN ELEVATED ALONG THE SW MTN RIDGES
AND SOUTH-FACING ESCARPMENT. WIDESPREAD LOW CLOUDS ARE EXPECTED
TONIGHT WHICH ALONG WITH THE HIGH DEWPOINTS WILL RESULT IN MIN
TEMPS IN THE LOWER 60S THRU THE NIGHT ACROSS MOST OF THE PIEDMONT,
AND 50S FOR THE MOUNTAIN VALLEYS. MORNING MINS MAY BE NEAR THE
DAILY HI-MIN RECORD, BUT COOLER TEMPS MAY ARRIVE BEFORE MIDNIGHT
MON NIGHT SO RECORDS ARE NOT NECESSARILY IN JEOPARDY.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
KEY MESSAGES:
1) STRONG TO SEVERE THUNDERSTORMS POSSIBLE MONDAY WITH A COLD
FRONT CROSSING THE AREA.
2) DRY WEATHER RETURNS TUESDAY WITH RAIN CHANCES INCREASING
BY MIDWEEK.
AS OF 300 AM SUNDAY: THE LATEST GUIDANCE HAS COME INTO PRETTY GOOD
AGREEMENT THAT CONVECTION ASSOCIATED WITH AN APPROACHING COLD
FRONT WILL STILL BE JUST WEST OF THE FORECAST AREA 12Z MONDAY,
AND WITH THIS SLIGHTLY LATER TIMING, INCREASES THE CONFIDENCE THAT
CONVECTION WILL HAVE SOME INSTABILITY TO WORK WITH AS IT CROSSES
THE FORECAST AREA LATER IN THE DAY. THE WINDOW FOR SEVERE STORMS
APPEARS TO BE FROM AROUND MIDDAY TO EARLY EVENING MONDAY, WITH
STORMS TRACKING FROM WEST TO EAST. SOME OF THE CAMS STILL SUGGEST
THAT A LINE OF STORMS COULD RACE OUT AHEAD OF THE FRONT AND PUSH
INTO THE NC MOUNTAINS BEFORE DAYBREAK, BUT THE ACTIVITY WEAKENS
SIGNIFICANTLY AND DOESN'T LOOK VERY ROBUST. THE 00Z HRRR SHOWS
THE LINE OF CONVECTION STRENGTHENING OVER AL/GA, ENTERING OUR GA
COUNTIES AROUND NOON. FROM THERE, STORMS LOOK TO FAVOR A LINEAR
MODE, WITH DAMAGING WIND GUSTS BEING THE MAIN THREAT. BUT SOME
DISCRETE STORMS MAY FORM AHEAD OF THE LINE, AND SOME EMBEDDED
SUPERCELLS MAY FORM IN THE LINE, BOTH OF WHICH MAY PRODUCE A
LARGE HAIL AND TORNADO THREAT. LOW-LEVEL SHEAR (30+ KT OF 0-1 KM
SHEAR AND 0-3KM SRH 200-300 M2/S2)LOOKS ADEQUATE FOR TORNADOES,
ESPECIALLY ACROSS THE PIEDMONT. THE CONVECTION WILL HAVE GOOD
UPPER SUPPORT WITH A DYNAMIC UPPER TROUGH CROSSING THE AREA. SPC
HAS UPGRADED THE RISK TO ENHANCED FOR ALL OF OUR FOOTHILLS AND
PIEDMONT ZONES, MAINLY DUE TO INCREASED TORNADO THREAT. QPF LOOKS
TO BE GENERALLY 0.25"-0.5", WITH HIGHER AMOUNTS POSSIBLE IN THE
SW-FACING SLOPES OF THE MOUNTAINS. THUNDERSTORMS SHOULD PUSH EAST
OF THE AREA EARLY IN THE EVENING, WITH LINGERING SHOWERS POSSIBLE,
MAINLY IN THE MOUNTAINS AS THE UPPER TROUGH PASSES.
CAA BEHIND THE FRONT SHOULD BRING TEMPS BACK DOWN TO NEAR NORMAL
MONDAY NIGHT THRU TUESDAY, AS HIGH PRESSURE NOSES IN FROM THE
NORTH. DRY AIR WILL BRING RH BACK DOWN INTO THE 25-35% RANGE
TUESDAY AFTN, WITH LIGHT WINDS.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
KEY MESSAGES
1) THE FORECAST HAS TRENDED DRIER IN THE MEDIUM RANGE, AS A STRONG
RIDGE BUILDS ACROSS THE SOUTHEAST
2) TEMPERATURES WARM TO WELL ABOVE NORMAL THROUGH THE PERIOD.
AS OF 140 AM SUNDAY: THE MEDIUM RANGE WILL BE DOMINATED BY A STRONG
UPPER RIDGE THAT WILL BUILD OVER THE SOUTHEAST THRU THE END OF THE
WEEK. THE 00Z GUIDANCE HAS TRENDED STRONGER WITH THE RIDGE, AND THIS
LOOKS TO SUPPRESS PRECIP CHANCES, DESPITE AN INCREASE IN HUMIDITY
WITHIN A SOUTHERLY TO SOUTHWESTERLY FLOW REGIME. WEDNESDAY WILL HAVE
THE BEST RAIN CHANCES, AS A WARM FRONT OF SORTS LIFTS NORTH THRU THE
AREA. THERE WILL BE A FEW HUNDRED J/KG OF CAPE TO SUPPORT A FEW
EMBEDDED THUNDERSTORMS IN WHATEVER CONVECTION MAY DEVELOP, BUT THE
SEVERE THREAT SHOULD BE LOW AS FORCING WON'T BE STRONG. THE LATEST
NBM STILL HAS SLGT CHC TO CHC POPS THURSDAY, ESPECIALLY IN THE
MOUNTAINS, BUT IF MODEL TRENDS HOLD, THESE WILL LIKELY BE LOWERED IN
LATER FORECASTS. FRIDAY AND SATURDAY LOOK LARGELY DRY, AS THE UPPER
HIGH WILL BE AT ITS STRONGEST AND DRIFTS WESTWARD TOWARD FL. THE
BIGGEST STORY WILL LIKELY BE THE UNUSUALLY WARM TEMPS FOR EARLY
APRIL. HIGHS MAY REACH THE UPPER 80S FRIDAY IN THE I-85 CORRIDOR AND
SOUTHEAST. LOWS WILL LIKELY BE IN THE LOW TO MID 60S EACH NIGHT
OUTSIDE THE MOUNTAINS. DEWPTS WILL CREEP INTO THE 50S TO LOWER 60S,
WHICH WILL HELP KEEP RH ABOVE CRITICAL LEVELS FOR WILDFIRE RISK.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: WARM UPGLIDE OCCURRING ALOFT WILL PRODUCE
WIDESPREAD LOW VFR CIGS OVER THE TERMINALS THIS MORNING, WITH MVFR
LIKELY DEVELOPING FOR A TIME LATE MORNING TO EARLY AFTN. LIGHT
PRECIP ALREADY ONGOING ALONG THE SOUTH-FACING RIDGES SW OF KAVL,
AND SHRA WILL GRADUALLY BECOME POSSIBLE AT THE SC SITES BY LATE
MORNING AND EARLY-MID AFTN AT KCLT/KHKY. A SECONDARY WARM FRONT
ARRIVING THIS AFTN, AND PROGRESSING SW TO NE ACROSS THE AREA
THRU EVENING, WILL KICK OFF ANOTHER ROUND OF SHOWERS, WARRANTING
PROB30/TEMPO MENTION. INSTABILITY WILL BE SUFFICIENT AT THE SC
SITES THAT TSRA ARE MENTIONED IN THE PROB/TEMPO INSTEAD, WITH
LOW MVFR TO IFR CIGS POSSIBLE IN THAT TIME. SHRA MAY DECREASE IN
COVERAGE IN THE EVENING BUT WIDESPREAD IFR IS EXPECTED TO REMAIN
IN PLACE THRU DAYBREAK MON, NOT IMPROVING UNTIL MIDDAY. CONTINUED
S TO SSW WINDS WITH 15-20 KT GUSTS POSSIBLE THIS AFTN.
OUTLOOK: SHRA/TSRA AND ASSOCIATED RESTRICTIONS ON MONDAY WITH
DAMAGING WINDS AND LARGE HAIL POSSIBLE. DRYING IS EXPECTED ON
TUESDAY. SOME LIGHT PRECIP IS POSSIBLE BY THURSDAY, BUT MORE LIKELY
NOT UNTIL NEXT WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
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