602
FXUS62 KGSP 050730
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
330 AM EDT MON MAY 5 2025
SYNOPSIS
DRIER WEATHER IS EXPECTED THROUGH TUESDAY WITH TEMPERATURES
REMAINING BELOW NORMAL FOR EARLY MAY. ANOTHER UNSETTLED PATTERN
WILL LIKELY DEVELOP BY MID-WEEK, WITH ELEVATED CHANCES FOR RAIN
AT TIMES WEDNESDAY THROUGH FRIDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 258 AM EDT MONDAY...
KEY MESSAGES: 1) CLEAR AND SUNNY CONDITIONS EXPECTED TODAY, WITH
PLEASANT SPRINGTIME TEMPERATURES IN THE 70S.
2) SOME AFTERNOON SHOWERS AND PERHAPS EVEN SOME THUNDERSTORMS
COULD DEVELOP OVER THE NC MOUNTAINS, BUT SEVERE RISK APPEARS LOW.
FINALLY EXPECT A QUIET STRETCH OF WEATHER TODAY AND TONIGHT, AS SW
FLOW ON THE CUSP OF AN UPPER LOW CENTERED OVER THE WESTERN EDGE OF
THE CUMBERLAND PLATEAU DOES LITTLE TO OVERCOME GENERALLY STABLE
CONDITIONS OVER THE WESTERN CAROLINAS. MOSTLY DRY CONDITIONS
REMAIN IN PLACE BEHIND A COLD FRONT NOW LOCATED OVER THE COASTAL
PLAIN OF THE CAROLINAS AND MORE SMEARED THAN IT LOOKED YESTERDAY.
VALLEY STRATUS IS LOOKING INCREASINGLY PROMINENT ON SATELLITE
IMAGERY OVER THE LITTLE TENNESSEE VALLEY...BUT REMAINS SCANT IN
THE FRENCH BROAD. CROSSOVER TEMPERATURES WOULD SUGGEST THAT IT'S
TOO DRY FOR VALLEY FOG TO MAKE IT TO THE LOWER PART OF THE FRENCH
BROAD...BUT CAN'T RULE OUT SOME PATCHY FOG IN SHELTERED AREAS THERE.
LOWS ACROSS THE AREA ARE EXPECTED TO FALL INTO THE LOWER 50S, OR
EVEN UPPER 40S IN SOME SPOTS ACROSS THE NC FOOTHILLS...AND INTO
THE MID- TO LOWER 40S ACROSS THE HIGH TERRAIN.
EXPECT MOSTLY QUIET CONDITIONS TO PERSIST TODAY. A SPOKE OF
MIDLEVEL VORTICITY WILL ROUND THE UPPER LOW TODAY, MORE OR LESS
DURING PEAK HEATING, WHICH LIKE YESTERDAY WILL HAVE THE EFFECT OF
SUBTLY STEEPENING MIDLEVEL LAPSE RATES. SOUNDINGS INDICATE THAT
AREAS EAST OF I-26 WILL NONETHELESS REMAIN TO CAPPED (AND DRY) TO
SUPPORT MORE THAN A FAIR-WEATHER CUMULUS FIELD...BUT LOCATIONS WEST
OF I-26 COULD BECOME UNCAPPED. THIS IS REFLECTED IN CAM OUTPUT,
WHICH DEPICTS A FEW SHOWERS BREAKING OUT OVER THE NC MOUNTAINS
DURING THE EARLY AFTERNOON...CLEARING OUT BEFORE THE DIURNAL
MAXIMUM, HOWEVER, AS THEY FOLLOW THE SYNOPTIC FORCING NORTH.
CAN'T RULE OUT SOME THUNDER WITH THIS ACTIVITY...BUT SEVERE RISK
LOOKS NIL. HIGHS WILL CLIMB INTO THE LOWER TO MID-70S ACROSS MOST
OF THE AREA. CLEAR CONDITIONS WILL PERSIST INTO MONDAY NIGHT,
AND LOWS TUESDAY MORNING SHOULD LAND WITHIN A CATEGORY OF THIS
MORNING'S.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
AS OF 215 AM MON, KEY MESSAGES:
1. MOSTLY CLEAR TUESDAY WITH HIGHS A SHADE BELOW NORMAL.
2. CLOUDS ARRIVE TUE NIGHT AND REMAIN ABUNDANT FOR THE REMAINDER
OF THE SHORT TERM PERIOD, ALONG WITH A CHANCE OF PRECIP FOR ALL
ZONES AT SOME POINT WED AND/OR WED NIGHT.
HEIGHTS STILL LOOK TO RISE TUESDAY AS UPPER LOW MOVES TOWARD THE
NE CONUS. WEAK SFC HIGH SUBSEQUENTLY WILL BUILD ACROSS THE LOWER
OH VALLEY AND INTO OUR AREA. STILL EXPECTING DRY AND MOSTLY CLEAR
CONDITIONS FOR THE CWA TUESDAY WITH MAX TEMPS WARMING BACK ALMOST
TO NORMAL. MODELS GENERALLY HAVE TRENDED HIGHER WITH HEIGHTS IN
THE MIDWEST TUE-WED, AS OMEGA BLOCK TRANSITIONS TO A REX BLOCK. A
WARM FRONT CONTINUES TO BE SHOWN AHEAD OF THE WESTERN UPPER LOW AND
WILL APPROACH THE AREA TUE NIGHT FROM THE SW; IF NOTHING ELSE CLOUD
COVER IS EXPECTED TO EXPAND OVER THE CWA. PERHAPS IN RESPONSE TO THE
STRONGER RIDGE/HIGH, DEPICTIONS OF MOISTURE/PRECIP ASSOCIATED WITH
THE FRONT HAVE BACKED OFF SUCH THAT WE NOW FEATURE ONLY CHANCE POP
ON WED IN AREAS SOUTHWEST OF I-26, AND NO MENTION OF PRECIP IN OUR
NORTHEAST ZONES DURING THE DAY. AS THE FRONT WILL BE MOVING OVER
THE DRY CONTINENTAL SFC HIGH AND MOISTENING OCCURS FROM THE TOP
DOWN, THERE REMAINS AN INDICATION OF WEDGELIKE DIABATIC COOLING
WHICH LEADS TO MAX TEMPS SEVERAL BELOW NORMAL IN THE SW HALF OF
THE AREA, BUT NEAR NORMAL IN THE NE.
AS THE EASTERN UPPER LOW IS ABSORBED INTO THE OPEN WAVE OVER
ONTARIO/QUEBEC, HEIGHTS BEGIN TO FALL AGAIN OVER THE APPALACHIANS.
THE WARM FRONT WILL LINGER ALTHOUGH IT MAY DRIFT SOUTHWARD IN
RESPONSE. THE HEIGHT FALLS TAKE LONGER TO DEVELOP ON THE ECMWF
AND IT SUGGESTS WEAK WARM UPGLIDE MAY STILL BE RAMPING UP OVER
THE AREA. UPPER DIVERGENCE AIDING LIFT OVER THE FRONT APPEARS TO
SHIFT EAST, SO POPS DO TREND HIGHER IN OUR EASTERN ZONES WED
NIGHT. IF A GFS LIKE SOLUTION VERIFIES, PRECIP LIKELY WILL TAPER
OFF WITH SOME DRYING OCCURRING ALOFT AND AS THE DYNAMIC FORCING
EXITS. WITH CONFIDENCE STILL LIMITED BY MODEL DIFFERENCES, POPS
ONLY DIMINISH SLIGHTLY TOWARD DAYBREAK THU AND DO NOT LEAVE THE
FORECAST.
LONG TERM /THURSDAY THROUGH SUNDAY/
AS OF 250 AM MON: REX BLOCK WILL REMAIN IN PLACE ACROSS THE CENTRAL
CONUS THURSDAY. A DEEP OPEN TROUGH OVER THE NE CONUS WILL DRIVE A
COLD FRONT SOUTH THRU THE OHIO VALLEY THEN OR THURSDAY NIGHT. THE
PATTERN IS MURKY OVER THE CAROLINAS AND GEORGIA; KEY DIFFERENCE IS
THE POSITION OF THE TROUGH AXIS, WHICH AFFECTS HOW QUICKLY THE COLD
FRONT PUSHES SOUTH. LOW-LEVEL FLOW WILL BE WEAK MOST OF THE DAY AND
THERE IS LITTLE IN THE WAY OF SYNOPTIC FORCING. WEAKLY UNSTABLE
PROFILES ARE SEEN AND THAT IS ARGUABLY THE MAIN DRIVER FOR POPS;
MODEL QPF RESPONSE IS SPOTTY. TEMPS TREND SLIGHTLY WARMER AND JUST
ABOVE NORMAL THAT DAY. DECENT AGREEMENT THAT THE COLD FRONT WILL
PUSH SOUTH INTO THE CWA LATE THU NIGHT OR FRIDAY AT WHICH TIME POPS
PEAK FOR THE FORECAST PERIOD, BEING LIKELY OVER THE SOUTHERN HALF
OF THE CWA AND THE SW NC MOUNTAINS. TEMPS TREND COOLER AS THE COLD
FRONT COMES IN, BEING BELOW NORMAL BY SATURDAY.
BY LATE FRIDAY THE EASTERN TROUGH, AND AN EXPANSIVE WESTERN RIDGE,
BEGIN TO CAPTURE THE COMPONENTS OF THE REX BLOCK, SUCH THAT THE
PATTERN SHOWN ON THE DETERMINISTIC ECMWF AND GDPS AND MOST MEMBERS
OF THE GLOBAL ENSEMBLES SHOW A MORE TYPICAL, IF NOT AMPLIFIED,
RIDGE-TROUGH PATTERN. IN THEIR SCENARIOS, THE EASTERN US IS LARGELY
UNDER THE INFLUENCE OF A CONTINENTAL SFC HIGH, DRYING WOULD BEGIN
SATURDAY, AND DEEP MOISTURE LARGELY KEPT OFFSHORE BY SUNDAY OR
MONDAY SUGGESTING A GENERALLY DRY FORECAST FOR OUR AREA. SOME
MEMBERS, AND THE OPERATIONAL GFS, SHOW THE UPPER LOW FAILING TO
BE CAPTURED AND INSTEAD MIGRATING TO THE DEEP SOUTH. THE PRESENCE
OF THE UPPER LOW COULD MEAN ANY CONTINENTAL HIGH WOULD BE LESS
LIKELY TO SCOUR OUT MOISTURE FROM THE AREA. WITH THAT, AND TIMING
DIFFERENCES BETWEEN THE MODELS, 20-40% POPS REMAIN IN THE CWA
THROUGH EARLY MONDAY, MAINLY ON A DIURNAL CYCLE. FURTHERMORE, THE
GFS AND A FEW EC ENS MEMBERS DEPICT A WEAK COASTAL LOW DEVELOPING
BY MONDAY NEAR THE GA COAST IN RESPONSE TO THE UPPER LOW, SO THAT
REMAINS AN ITEM OF INTEREST ALSO.
AVIATION /08Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: STILL EXPECT A VFR TAF PERIOD, WITH THE
EXCEPTION OF SOME POSSIBLE VALLEY FOG MAKING IT TO KAVL IN THE
WEE HOURS OF MONDAY MORNING. GENERALLY FEW/SKC OVERNIGHT WILL
GIVE WAY TO A SPREAD OF FAIR WEATHER CU ACROSS THE AREA MONDAY
AFTERNOON, OWING TO MOISTURE WITHIN A SHALLOW, CAPPED UNSTABLE
LAYER AT 5-6 KFT. OVER THE MOUNTAINS, SOME WIDELY SCATTERED
RIDGETOP CONVECTION MAY DEVELOP AS IT DID ON SUNDAY, BUT WITH
ONLY A 10-20% CHANCE OF AFFECTING KAVL...SO NO MENTION IN THE TAF.
WSW WINDS EXPECTED THROUGH THE DAYLIGHT HOURS, GRADUALLY TENDING
TOWARD WNW AFTER SUNSET...WHILE SKIES REMAIN CLEAR.
OUTLOOK: VFR EXPECTED THROUGH THE FIRST PART OF THE WEEK.
RESTRICTIONS RETURN FROM MID-WEEK ONWARD.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...MPR
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...MPR
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