441
FXUS62 KGSP 131931
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
231 PM EST WED NOV 13 2024
SYNOPSIS
CLOUDS AND PRECIPITATION WILL MOVE IN OVERNIGHT AND MAKE FOR A VERY
DAMP AND CHILLY THURSDAY. DRY WEATHER AND A WARMING TREND ARE
EXPECTED FRIDAY THROUGH MONDAY.
NEAR TERM /THROUGH THURSDAY/
AS OF 210 PM EST WEDNESDAY: QUITE A CHANGE OF WEATHER IN STORE FOR
LATE TONIGHT AND THURSDAY. HIGH PRESSURE REMAINS IN PLACE IN COLD
AIR DAMMING CONFIGURATION ACROSS THE AREA AS A COLD FRONT APPROACHES
FROM THE WEST. EXPECT AN INCREASE IN MOISTURE AND FORCING AS THE
FRONT MOVES IN FROM THE WEST. CLOUDS WILL INCREASE FROM THE TOP DOWN
OVERNIGHT AS THE MOISTURE DEEPENS. THERE IS GOOD SYNOPTIC SCALE
FORCING AS A SHORT WAVE MOVES IN WITH THE FRONT AND DIVERGENCE
INCREASES WITH AN UPPER JET. ISENTROPIC LIFT STRENGTHENS AS A
SOUTHEASTERLY LOW LEVEL JET DEVELOPS, WHICH ALSO INCREASES UPSLOPE
FLOW. PRECIP CHANCES RAPIDLY INCREASE AFTER MIDNIGHT WITH
CATEGORICAL POP FOR THE MOUNTAINS. CAT POP SPREADS ACROSS THE AREA
EARLY THURSDAY MORNING WITH CHANCES DIMINISHING FROM WEST TO EAST
DURING THE AFTERNOON AS THE COLD FRONT MOVES IN FROM THE WEST.
GUIDANCE HAS SHOWN AN UPTICK IN QPF WITH MOST LOCATIONS ALONG AND
NORTH OF THE I-85 CORRIDOR, EXCEPT FOR SOME NORTHWESTERLY FACING
RAIN SHADOW LOCATIONS, SEEING AN 1 TO 1.25 INCHES OF RAIN. SOUTH OF
I-85 WILL STILL SEE BETWEEN 0.5 AND 1 INCH, WITH SLIGHTLY LOWER
AMOUNTS FOR THE RAIN SHADOW AREAS. FAVORED UPSLOPE AREAS WILL SEE
CLOSER TO 2 INCHES, BUT ANTECEDENT CONDITIONS SHOULD PRECLUDE ANY
FLOODING. CAN'T RULE OUT SOME ELEVATED CONVECTION FOR THE I-77
CORRIDOR DURING THE AFTERNOON, BUT CHANCE IS LOW GIVEN THE STRENGTH
OF THE STABLE SURFACE LAYER.
EVEN OUR COLDEST GUIDANCE HAS BACKED OFF ON ANY FREEZING RAIN
POTENTIAL FOR THE NORTHERN BLUE RIDGE WITH WET BULB TEMPS ABOVE
FREEZING. THEY HAVE EVEN BACKED OFF ON PRECIP ONSET SLEET POTENTIAL
AS THE COLD NOSE IS SMALLER AND SHORTER LIVED. THAT SAID, WOULDN'T
BE SURPRISED IF THESE AREAS SEE AN INITIAL BURST OF SLEET AS THE
TEMPS WET BULB DOWN WITH THE DEVELOPING PRECIP. ANY SLEET SHOULD BE
VERY LIGHT AND BRIEF.
SOUTHEASTERLY WIND SPEEDS AND GUSTS WILL INCREASE ACROSS THE HIGHER
ELEVATIONS OVERNIGHT INTO THURSDAY MORNING WITH THE STRENGTHENING
LOW LEVEL JET THEN FLIP TO THE NORTHWEST DURING THE AFTERNOON BEHIND
THE FRONT. OCCASIONAL NORTHEASTERLY GUSTS WILL BE SEEN OUTSIDE OF
THE MOUNTAINS AS WELL. ALL GUSTS SHOULD REMAIN BELOW ADVISORY
CRITERION.
LOWS TONIGHT WILL BE AS MUCH AS 5 DEGREES ABOVE NORMAL WITH A NON-
DIURNAL TREND LIKELY ACROSS THE MOUNTAINS, TEMPS RISING LATE IN THE
NIGHT AFTER WET BULBING DOWN DURING PRECIP ONSET. HIGHS THURSDAY
WILL SHOW A TYPICAL CAD CONFIGURATION. HIGHS AROUND 15 DEGREES BELOW
NORMAL OUTSIDE OF THE MOUNTAINS, AND 10 DEGREES BELOW NORMAL FOR
MUCH OF THE MOUNTAINS EXCEPT FOR THE LITTLE TN BASIN AND OTHER LOWER
VALLEY LOCATIONS NEAR THE TN BORDER WHERE 5 DEGREES BELOW NORMAL
WILL BE COMMON.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
AS OF 230 PM EST WEDNESDAY: PRECIP WILL BE MOVING OUT AS WE MOVE
INTO THE SHORT TERM, WITH SOME FRONTAL PRECIP STILL IN THE NW
PIEDMONT AND MOISTURE ASSOCIATED WITH THE UPPER TROUGH ITSELF PUSHING
INTO THE MOUNTAINS. POPS WILL LIFT RAPIDLY FROM PIEDMONT BUT NW
UPSLOPE FLOW WILL ALLOW PRECIP TO LINGER TOWARD DAYBREAK IN THE
NORTHERN MOUNTAINS, THOUGH CAA NOT QUITE STRONG ENOUGH TO BRING ANY
MIXED PRECIP CONCERNS AT THIS TIME. NEW GUIDANCE HAS COME DOWN WITH
POST-FRONTAL WIND GUSTS EARLY FRIDAY IN THE HIGHEST ELEVATIONS BUT
STILL EXPECT GUSTY WINDS 35MPH+ WITH MOUNTAIN WAVE ACTIVITY AS THE
UPPER TROUGH PUSHES THROUGH.
GRADIENT WEAKENS DURING THE DAY ON FRIDAY AND AS USUAL POST-CAD WITH
SUNSHINE AND DOWNSLOPE FLOW EXPECT A SIGNIFICANT WARM-UP WITH HIGHS
IN THE MID 60S IN THE PIEDMONT. WITH UPPER RIDGING BUILDING IN JUST
TO THE WEST ON SATURDAY AND SOUTHERLY WAA INCREASING AT THE SURFACE,
EXPECT ANOTHER UPTICK FOR HIGHS AS WE START THE WEEKEND.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AS OF 300 PM EST WEDNESDAY: UPPER RIDGE WITH SURFACE HIGH WILL
DOMINATE THE AREA AS WE START THE EXTENDED, WITH THE WAVETRAIN
MOVING EAST QUICKLY INTO EARLY NEXT WEEK. REALLY PLEASANT CONDITIONS
EXPECTED WITH GRADUAL WARMING EACH DAY THROUGH TUESDAY AHEAD OF THE
NEXT SYSTEM, WHICH WILL BE GEARING UP OVER THE PLAINS EARLY IN THE
WEEK. THERE'S QUITE A BIT OF UNCERTAINTY THIS FAR OUT AS TO EXACTLY
HOW THE PATTERN WILL EVOLVE AS THE SYSTEM APPROACHES, BUT RIGHT NOW
THE PLAINS TROUGH IS PROGGED TO LIFT TOWARD THE UPPER MS VALLEY BY
TUESDAY MORNING, DRAGGING A COLD FRONT TOWARD THE TN VALLEY AND
BRINGING POPS INTO EXTREME WESTERN ZONES TUESDAY MORNING. NO
CONCERNS FOR WINTRY PRECIP AT THIS TIME, ALL LIQUID. GLOBAL MODELS
CURRENTLY HAVE THE FRONT SORT OF FALLING APART OVER THE APPALACHIANS
AS THE INITIAL UPPER LOW GETS ABSORBED INTO THE LONGWAVE PATTERN, A
DEEPER TROUGH DIGGING OUT OF CANADA THAT LOOKS TO IMPACT THE CENTER
OF THE COUNTRY TOWARDS THE EXTENDED. FOR NOW HAVE KEPT POPS
GENERALLY AT MID-RANGE CHANCE IN THE MOUNTAINS AND SLIGHT CHANCE
EAST AT THE END OF THE PERIOD.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: DRY HIGH PRESSURE WITH NE WIND, S AT KAVL,
AND MOSTLY CLEAR SKIES THIS AFTERNOON. MOISTURE INCREASES AHEAD OF A
COLD FRONT APPROACHING FROM THE WEST OVERNIGHT. THIS LEADS TO
INCREASING AND LOWERING CLOUDS. PRECIP CHANCES ALSO INCREASE
OVERNIGHT AS FORCING INCREASES. EXPECT LOW VFR CIGS IN THE 06Z TIME
FRAME WITH MVFR VSBY AND CIGS IN RAIN NEAR 12Z. CONDITIONS THEN
DETERIORATE RAPIDLY FROM WEST TO EAST AS RAINFALL RATES INCREASE AND
CIGS FALL TO IFR THEN LIFR WITH VLIFR POSSIBLE DURING THE DAY. VSBY
WILL RANGE FROM MVFR TO IFR. NE WIND CONTINUES THROUGH THE PERIOD
WITH LOW END GUSTY WINDS POSSIBLE. KAVL WILL SEE S TO SE WIND
THROUGH THE PERIOD. LLWS MAY BECOME A CONCERN LATE TONIGHT OR DURING
THE DAY THU, DEPENDING ON THE STRENGTH AND DIRECTION OF THE THE LOW
LEVEL JET.
OUTLOOK: HIGH PRESSURE BRINGS DRY AND VFR CONDITIONS BACK FRIDAY
INTO EARLY NEXT WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...TDP
NEAR TERM...RWH
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...RWH
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