735
FXUS62 KGSP 140325
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1025 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 930 PM EST WEDNESDAY: A SURFACE RIDGE REMAINS IN PLACE IN COLD
AIR DAMMING CONFIGURATION ACROSS THE AREA THIS EVENING AS A COLD
FRONT APPROACHES FROM THE WEST. THE LEADING EDGE OF WIDESPREAD
SHOWERS ASSOCIATED WITH DEEPER MOISTURE AND FORCING IS BEGINNING TO
MOVE INTO THE FAR WESTERN PART OF THE CWA LATE THIS EVENING, AND
WILL STEADILY OVERSPREAD THE CWA THROUGH THE OVERNIGHT. 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.
CATEGORICAL POPS SPREAD ACROSS THE AREA THROUGH EARLY THURSDAY
MORNING, WITH CHANCES DIMINISHING FROM WEST TO EAST DURING THE
AFTERNOON AS THE COLD FRONT MOVES IN FROM THE WEST. THE LATEST
SURFACE ANALYSIS DEPICTS WET BULB TEMPS AT OR JUST BELOW FREEZING
ACROSS THE HIGHEST ELEVATIONS OF WESTERN NC THIS EVENING. FORECAST
SOUNDINGS CONTINUE TO INDICATE STRONG ADVECTION OF WARM AND MOIST
AIR OCCURRING ABOVE THE STABLE SURFACE LAYER, WITH A VERY DEEP AND
STRONG WARM NOSE DEVELOPING NOT LONG AFTER PRECIP DEVELOPMENT. THUS,
WHILE THERE COULD BE A BRIEF PERIOD OF SLEET OR -FZRA ABOVE 4500' OR
SO WARM ADVECTION WILL QUICKLY ERADICATE ANY LINGERING COLD
LAYERS.
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. GIVEN THE STRENGTH OF THE FORCING AND SOME SCANT/ELEVATED
INSTABILITY, CAN'T RULE OUT A LIGHTNING STRIKE HERE OR THERE,
ESPECIALLY DURING THE DAYLIGHT HOURS.
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. TEMPERATURES
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 /04Z 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
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