940
FXUS62 KGSP 140004
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
704 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 650 PM EST WEDNESDAY: QUITE A CHANGE OF WEATHER IN STORE FOR
LATE TONIGHT INTO 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. STRONG SYNOPTIC SCALE FORCING IS
EXPECTED AS A NEGATIVELY TILT SHORT WAVE TROUGH ACCOMPANIES THE
FRONT AND DIVERGENCE INCREASES IN THE EXIT REGION OF AN UPPER JET
MAX. ISENTROPIC LIFT STRENGTHENS AS A SOUTHEASTERLY LOW LEVEL JET
DEVELOPS...INCREASING 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.
MOST LOCATIONS ALONG AND NORTH OF THE I-85 CORRIDOR, EXCEPT FOR SOME
NORTHWESTERLY FACING RAIN SHADOW LOCATIONS, ARE EXPECTED TO RECEIVE
A SOLID SOAKING OF 1 TO 1.25 INCHES OF STORM TOTAL RAINFALL. 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 THE 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 AND A VERY DEEP WARM NOSE. 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 /00Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR/INCREASING AND THICKENING HIGH CLOUDS ARE
EXPECTED FOR THE FIRST 6-9 HOURS OF THIS FORECAST CYCLE...FOLLOWED
BY QUICKLY DETERIORATING FLIGHT CONDITIONS BETWEEN 09-12Z, AS A
MOIST FRONTAL SYSTEM BEGINS IMPACTING THE AREA, BRINGING WIDESPREAD
RAIN/REDUCED VISBY AND LOWERING CIGS. IFR CIGS AND PERSISTENT
RAINFALL ARE EXPECTED AT ALL SITES BY LATE MORNING, WITH
RESTRICTIONS LIKELY PERSISTING THROUGH THE END OF THE PERIOD, EVEN
AS THE RAIN TAPERS OFF DURING THE AFTERNOON/EARLY EVENING. PRIMARILY
MVFR VISBY IS ANTICIPATED, BUT PERIODS OF 1-2SM ARE LIKELY IN
MODERATE/OCCASIONALLY HEAVY RAIN. THESE LOWER VISBY/S WILL BE
ADDRESSED IN LATER FORECAST UPDATES. OTHERWISE, WINDS WILL FAVOR NE
AT 5-10 KTS THROUGH MUCH OF THE PERIOD (EXCEPT FOR SE AT KAVL). LLWS
MAY BECOME A CONCERN, MAINLY BETWEEN SUNRISE AND NOON THURSDAY,
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...JDL/RWH
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JDL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page