711
FXUS62 KGSP 301858
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
258 PM EDT SUN MAR 30 2025
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES THROUGH TONIGHT INTO MONDAY AS A
COLD FRONT APPROACHES FROM THE WEST. A FEW OF THESE STORMS COULD BE
SEVERE. DRY HIGH PRESSURE RETURNS TUESDAY, RESULTING IN WELL ABOVE
NORMAL TEMPERATURES ACROSS THE REGION LATE IN THE WEEK.
NEAR TERM /THROUGH MONDAY/
AS OF 245 PM: SHOWER ACTIVITY (!) CONTINUES TO GROW IN COVERAGE AND
INTENSITY ACROSS THE AREA ALONG/WEST OF I-26 AS ISENTROPIC LIFT AND
SOUTHERLY UPSLOPE FLOW WORK THEIR MAGIC THIS AFTERNOON. THERE'S
A GOOD CHANCE THAT MOST LOCATIONS WILL GET AT LEAST A LITTLE
SOMETHING, ESPECIALLY THE AREAS NEAR THE BLUE RIDGE ESCARPMENT. THE
SHOWERS HAD DEVELOPED IN A PLUME OF SFC-BASED CAPE UPWARDS OF 500
J/KG OR SO, AND THIS PLUME SHOULD ALSO EXPAND THRU THE AFTERNOON,
SO EASTWARD DEVELOPMENT OF THE SHOWERS CAN ALSO BE PLANNED. STILL
EXPECTING A FEW EMBEDDED THUNDERSTORMS EAST OF THE MTNS UNTIL WE
LOSE DAYTIME HEATING. FOR THE NEXT SEVERAL HOURS, TEMPS WILL BE
MODULATED BY SHOWER COVERAGE/MOVEMENT.
THE CURRENT SITUATION WILL PERSIST INTO THE OVERNIGHT HOURS, WITH
THE MILD SOUTHERLY FLOW OF MOISTURE AND ISENTROPIC LIFT SUPPORTING
SCT/NUMEROUS SHOWERS AROUND THE WESTERN PERIPHERY OF THE LARGE HIGH
OFFSHORE. IN ALL LIKELIHOOD THE SHOWER PRODUCTION WILL RETREAT TO
THE SOUTHERLY UPSLOPE AREAS NEAR THE ESCARPMENT FOR THE BETTER PART
OF THE MID/LATE EVENING HOURS WHILE THE CONVECTION ASSOCIATED WITH
THE APPROACHING COLD FRONT REMAINS FAR ENOUGH TO OUR WEST. THE
AREAS AROUND THE FIRES STAND THEIR BEST CHANCE TO PICK UP SOME
MUCH NEEDED RAINFALL DURING THIS PERIOD, BECAUSE CONFIDENCE GOES
DOWN AFTER DAYBREAK AS TO HOW MUCH COVERAGE WE WILL SEE.
WHICH BRINGS US TO MONDAY. ON THE SYNOPTIC SCALE, THE FORCING LOOKS
ADEQUATE AND MOISTURE DEEP ENOUGH TO WARRANT PRECIP PROBS RAMPING
UP INTO THE CATEGORICAL RANGE INTO THE AFTERNOON. HOWEVER, THAT IS
MET WITH RESISTANCE IN THE CAM GUIDANCE, PARTICULARLY THE HRRR,
WHICH TREATS THE CONVECTION WITH NEGLECT AND PREJUDICE. QUITE
DISHEARTENING TO SEE THE HRRR ESSENTIALLY WASHING OUT THE
PRE-FRONTAL CONVECTION AS IT REACHES THE MTNS IN THE EARLY
MORNING. BUT, LIKE WE SAID ABOVE, THE FORCING WILL BE THERE,
SO THE PROBS WILL BE KEPT HIGH AND PERHAPS THE OTHER CAMS THAT
SHOW THE BETTER COVERAGE WILL BE MORE CORRECT. AS TO THE SEVERE
POTENTIAL, THE 12Z RUN OF THE HREF LOOKS RELATIVELY UNIMPRESSIVE
AND UNINSPIRED. THE BETTER ORGANIZATION OF STORMS DIVES TO THE SOUTH
IN THE MORNING, AS WAS ALWAYS SUSPECTED, LEAVING US IN THE WESTERN
CAROLINAS TO WONDER IF STORMS WILL REDEVELOP. THE RAP MANAGES STILL
TO DEVELOP SFC-BASED CAPE OF 500-1500 J/KG AND SHEAR 30-40KT,
SO THERE REMAINS SOME POTENTIAL FOR SEVERE STORMS, BUT THE CAMS
DO NOT RESPOND TO THE EXTENT THAT ONE MIGHT HAVE EXPECTED. WE WILL
MONITOR LATER DEVELOPMENTS, BUT FOR NOW, THE BETTER CHANCES APPEAR
TO BE EAST AND SOUTH. THE ACTIVITY SHOULD EXIT TO THE EAST LATE
IN THE DAY. TEMPS WILL REMAIN ABOVE NORMAL BY ABOUT TEN DEGREES.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
KEY MESSAGES:
1) DRY WEATHER RETURNS TUESDAY WITH RAIN CHANCES POSSIBLE BY MIDWEEK.
2) ABOVE NORMAL TEMPERATURES THURSDAY.
AS OF 155 PM SUNDAY: THE COLD FRONT CONTINUES TO MOVE THROUGH THE
AREA AND SHOULD BE CROSSING THE CWA MONDAY NIGHT. AFTER THE FROPA,
HIGH PRESSURE RETURNS AND SHUNTS RAIN CHANCES ON TUESDAY. THE
GENERAL SYNOPTIC FLOW TURNS MORE QUASI-ZONAL INTO MID WEEK BEFORE A
TROUGH BUILDS IN ACROSS THE ROCKIES AND AN AMPLIFYING RIDGE MOVES IN
FROM THE SOUTH. PREVIOUS FORECASTS HAD AN AREA OF LOW PRESSURE
FORMING OVER THE CENTRAL CONUS AND LIFTING NORTHWARD, TRAILING A
COLD FRONT ACROSS THE AREA. HOWEVER, RECENT GUIDANCE FROM THE
GFS/EURO BOTH SHOW A STOUT RIDGE EXPANDING AND PERSISTING OVER THE
AREA FROM ABOUT MIDWEEK ONWARD. THIS IS TRENDING RAINFALL POTENTIAL
EVEN DRIER AS THE AREA OF BETTER LIFT/CONVERGENCE IS NOW OFF THE NW
OF THE CWA. THIS DOES LOWER QPF RESPONSE AND POPS DOWN INTO THE
SLIGHT CHANCE RANGE AS CONFIDENCE IS DECREASING FOR RAIN POTENTIAL.
THESE HEIGHT RISES COULD SHUNT PRECIP CHANCES AND BRING TEMPERATURES
WELL ABOVE NORMAL THROUGH THE SHORT TERM AND INTO THE NEXT. ONE
POSITIVE NOTE IS SOUTHERLY WINDS RETURN WEDNESDAY NIGHT AND ADVECT
MORE MOISTURE, KEEPING RH VALUES WELL ABOVE ANY CRITICAL LEVELS.
TUESDAY LOOKS TO BE THE DRIEST DAY WITH RH VALUES IN THE 25%-35%
RANGE, BUT IMPROVING ONWARD.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
KEY MESSAGES
1) THE FORECAST HAS TRENDED DRIER, AS A STRONG RIDGE BUILDS ACROSS
THE SOUTHEAST
2) TEMPERATURES WARM TO WELL ABOVE NORMAL THROUGH THE PERIOD.
AS OF 200 PM SUNDAY: AS WAS THE CASE IN THE SHORT TERM, GUIDANCE
FROM THE GFS/EURO CONTINUE TO TREND TOWARD AN AMPLIFYING RIDGE OVER
THE SOUTHEAST THROUGH MOST OF THE FORECAST PERIOD. SOUTHERLY FLOW
REMAINS DOMINATE DURING THE TIME, SO MOISTURE REMAINS IN THE AREA.
THE RIDGE AXIS PUSHES WEST A BIT, SHUNTING ONCE AGAIN MOST OF THE
BETTER PRECIPITATION CHANCES OFF TO THE NORTH. BY DAY 7, MODELS HINT
AT THE RIDGE STARTING TO WEAKEN, BRINGING BACK RAIN CHANCES, BUT
THIS IS HIGHLY UNCERTAIN SINCE IT'S A WEEK AWAY. OVERALL, GUIDANCE
CONTINUES TO TREND DRIER FOR THE AREA, KEEPING NEEDED RAINFALL AWAY
ONCE AGAIN. GIVEN THE MOISTURE IN THE REGION, WON'T RULE OUT A FEW
SCATTERED SHOWERS, SO WILL KEEP SLIGHT CHANCE POPS FOR MOST OF THE
EXTENDED. ADDITIONALLY, CONFIDENCE IS INCREASING THAT THE AREA COULD
HAVE TEMPERATURES IN THE UPPER 80S TOWARD THE END OF THE FORECAST
PERIOD DEPENDING ON THE STRENGTH OF THE BUILDING RIDGE. OVERALL,
EXPECT WELL-ABOVE NORMAL TEMPERATURES AND LITTLE RAINFALL.
AVIATION /19Z SUNDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: EXTENSIVE CLOUDINESS ACROSS THE REGION EARLY
THIS AFTERNOON AS WARM MOIST UPGLIDE SUPPORTS THE DEVELOPMENT OF
LOW CLOUD LAYERS, THE LOWEST OF WHICH WAS SLOWLY LIFTING FROM MVFR
TO VFR AT ISSUANCE TIME. THIS COULD RESULT IN AT LEAST A TEMPORARY
MVFR CEILING AT MOST TERMINALS FOR THE NEXT FEW HOURS. MEANWHILE,
SHOWERS CONTINUE TO DEVELOP AND GROW IN NUMBER OVER THE WESTERN
HALF OF THE REGION WHERE THE SOUTHERLY UPSLOPE IS MOST PRODUCTIVE,
WHICH IS CONVENIENT BECAUSE THE VIS RESTRICTION CAN BE COUPLED TO
THE TEMPORARY CEILINGS. WIND SHOULD REMAIN S WITH SOME LOW-END GUSTS
AS WE MIX DEEPER THRU THE AFTERNOON. FOR TONIGHT, THE PRECIP CHANCES
WILL BRIEFLY GO BACK CLOSER TO THE BLUE RIDGE ESCARPMENT, BUT
GUIDANCE SUGGESTS THAT LOW CLOUDS WILL DEVELOP QUICKLY IN THE LATE
EVENING, PERHAPS INITIALLY AT THE MVFR LEVEL, BUT THEN DOWN INTO
THE IFR LEVEL. WHILE THIS SEEMS LOW CONFIDENCE AND IS MET WITH SOME
SKEPTICISM, THE PROLONGED SOUTHERLY MOIST FLOW COUNTS FOR SOMETHING,
AND THINK AT SOME POINT BEFORE MORNING OPS WE WILL INDEED DEVELOP
A LOW CLOUD CEILING IN THE IFR RANGE. NOT WILLING TO COMMIT FULLY
TO LIFR AT THIS TIME HOWEVER. THE CAMS SUGGEST THAT SHOWERS WILL
BE LIKELY FROM MID/LATE MORNING ONWARD, BUT NOT A RAINOUT. CAN'T
RULE OUT A THUNDERSTORM EITHER, BUT CONFIDENCE IS ONLY HIGH ENOUGH
AT KCLT AS THAT FORECAST GOES THRU THE AFTERNOON. SOME IMPROVEMENT
WILL BE SEEN RIGHT AFTER THE END OF THE PERIOD.
OUTLOOK: SHRA/TSRA AND ASSOCIATED RESTRICTIONS ON MONDAY AFTERNOON
WITH DAMAGING WINDS AND LARGE HAIL POSSIBLE. DRYING IS EXPECTED ON
MONDAY NIGHT AND 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...CP
NEAR TERM...PM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...PM
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