420
FXUS62 KGSP 181121
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
621 AM EST TUE FEB 18 2025
SYNOPSIS
DRY HIGH PRESSURE LINGERS OVER THE REGION TODAY. WINTRY WEATHER
IS LIKELY FOR PARTS OF THE AREA ON WEDNESDAY AS A FAST-MOVING LOW
PRESSURE SYSTEM PASSES ACROSS THE SOUTHEAST. DRY HIGH PRESSURE
RETURNS THURSDAY BRINGING VERY COLD WEATHER TO END THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 620 AM EST TUESDAY: ONE MORE CALM DAY AND EVENING BEFORE
WEATHER CHANGES TAKE PLACE. FOR NOW, HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA FROM THE NORTH THROUGH THE PERIOD. PERIODS OF CIRRUS,
AND SOME ALTOCU, WILL SPREAD ACROSS THE AREA TODAY. HIGHS WILL BE UP
TO 5 DEGREES BELOW NORMAL. WEAK SHORT WAVES APPROACH FROM THE WEST
OVERNIGHT IN THE ZONAL FLOW ACROSS THE AREA. THERE WILL BE AN
INCREASE IN MID LEVEL MOISTURE WITH THE WAVES. LOW LEVEL MOISTURE
ALSO INCREASES TOWARD MORNING AS ISENTROPIC LIFT BEGINS. STILL,
NEITHER THE SYNOPTIC NOR ISENTROPIC LIFT WILL BE STRONG ENOUGH FOR
SIGNIFICANT PRECIP CHANCES FOR MOST OF THE AREA. PRECIP MAY BEGIN
ALONG THE TN BORDER BY DAYBREAK, WHICH WOULD BE ONLY A SLIGHT CHANCE
OF SNOW WITH NO ACCUMS. CHANCES RAMP UP EARLY IN THE NEXT PERIOD.
LOWS WILL BE UP TO 5 DEGREES BELOW NORMAL.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 330 AM TUESDAY: STILL ON TRACK FOR A QUICK WINTRY WX EVENT
FOR MUCH OF THE FORECAST AREA WEDNESDAY INTO EARLY THURSDAY. LATEST
GUIDANCE HAS SIMILAR QPF TO PREVIOUS FCST CYCLE, SO CONFIDENCE
IS INCREASING IN AN ADVISORY-LEVEL EVENT FOR MUCH OF OUR NC
ZONES. CONFIDENCE REMAINS LOWER FOR OUR SC AND GA ZONES, DUE TO
MORE MARGINAL TEMPS FOR SNOW, SLEET, OR ICE ACCUMS.
AN UPPER SHORTWAVE TROUGH WILL EJECT OUT OF THE SOUTHERN PLAINS
AND PROVIDE STRONG DPVA OVER THE FORECAST AREA DURING THE DAY
WEDNESDAY. AT THE SFC, A SPRAWLING ARCTIC HIGH WILL BEGIN TO NUDGE
INTO THE MID-ATLANTIC, HELPING SUPPLY COLD AIR TO OUR REGION WITH A
HYBRID CAD SETUP. SFC LOW PRES WAVE WILL TRACK ALONG THE GULF COAST,
WITH ISENTROPIC LIFT AHEAD OF THE LOW SPREADING MOISTURE NORTH
OVER THE COLD AIR MASS. SOME OF THE GUIDANCE, LIKE THE HRRR, SHOW
A PRONOUNCED GAP IN THE DEEPER MOISTURE BETWEEN ATLANTIC MOISTURE
TO OUR EAST AND THE GULF MOISTURE TO OUR WEST. THIS RESULTS IN A
RELATIVE MINIMUM OF QPF RIGHT OVER THE CWFA. THE LATEST QPF REALLY
LOOKS TOO LOW FOR WARNING-CRITERIA SNOW OR ICE ACCUMS. ADD TO THE
UNCERTAINTY IS THERMAL PROFILES. THICKNESSES SHOULD SUPPORT MAINLY
ALL SNOW ACROSS THE MOUNTAINS AND MOST OF THE NC PIEDMONT, SO 1-2"
OF SNOW ACCUMS LOOKS LIKELY IN THESE AREAS. AFTER COORDINATING WITH
NEIGHBORING OFFICES, HAVE OPTED TO ISSUE A WINTER WEATHER ADVISORY
FOR ALL OUR NC ZONES AND ALSO RABUN COUNTY, GA. THE PRECIP BREAKING
OUT AROUND DAYBREAK WEDNESDAY WILL FALL MAINLY ON ROADS THAT ARE
ABOVE FREEZING. SO HOPEFULLY THAT WILL LIMIT IMPACTS. BUT AS THE LOW
TRACKS BY TO OUR SOUTH, THERE IS SOME POTENTIAL FOR FRONTOGENETICAL
BANDING THAT COULD LOCALLY ENHANCE SNOW RATES. CONFIDENCE ON WHERE
THAT HAPPENS REMAINS LOW. FOR OUR SC AND GA ZONES, A TRANSITION
ZONE OF RA/SN AND POTENTIALLY SOME IP/FZRA MAY SET UP, BUT LOOKS
LIKE IT WILL BE NARROW. MINOR SNOW ACCUMS MAY BE POSSIBLE ACROSS
THE NORTHERN UPSTATE AND YORK/CHESTER. BUT THAT SNOW SHOULD BE
MOSTLY ON GRASSY SURFACES AND AT THE MOMENT IS TOO LOW TO WARRANT
AN ADVISORY. TEMPS WILL HOVER NEAR FREEZING WHERE THE SNOW FALLS,
WITH HIGHS MAINLY IN THE 30S TO LOWER 40S.
COLD AIR SHOULD START TO FILTER IN WEDNESDAY EVENING, FREEZING
ROADS, WHILE PRECIP SHOULD BEGIN TO TAPER OFF FROM WEST TO
EAST. SNOW SHOWERS WILL LINGER ACROSS THE MOUNTAINS, AS MOIST
NWLY UPSLOPE FLOW RAMPS UP. THE GFS HAS A BAND OF SNOW FORM
ACROSS THE I-77 CORRIDOR THURSDAY MORNING, PERHAPS DUE TO ANOTHER
BAND OF FRONTOGENESIS AS THE SFC LOW DEEPENS AND MOVES INTO THE
ATLANTIC. BUT MOST OTHER GUIDANCE DOES NOT HAVE THIS. MINOR
ADDITIONAL SNOW ACCUMS MAY BE POSSIBLE, ESPECIALLY IN THE
MOUNTAINS. THIS COMBINED WITH THE COLD ROADS SEEMS TO WARRANT
HAVING THE WINTER WX ADVISORY GO THRU THURSDAY MORNING. NW FLOW
SNOW SHOWERS WILL LIKELY CONTINUE INTO THURSDAY AFTN, BUT THE REST
OF THE AREA SHOULD SEE CLEARING SKIES. GUSTY NW WINDS IS EXPECTED
ACROSS THE ENTIRE FORECAST AREA, BUT NOT EXPECTED TO REACH ADVISORY
CRITERIA, EXCEPT FOR THE HIGHEST PEAKS. HIGHS WILL BE 15-20 DEG
BELOW NORMAL WITH WIND CHILLS MAKING IT FEEL EVEN COLDER.
NW FLOW SNOW SHOWERS ARE EXPECTED TO TAPER OFF BY EARLY THURSDAY
EVENING, BUT NW WINDS WILL LINGER THRU THE NIGHT. THURSDAY LOOKS
TO BE THE COLDEST NIGHT OF THE WEEK, WITH LOWS IN THE SINGLE
DIGITS ACROSS MOST OF THE HIGH ELEVATIONS ABOVE 3500 FT, AND
TEENS ELSEWHERE. WIND CHILLS MAY DROP BELOW -5 IN THE NORTHERN NC
MOUNTAINS, POSSIBLY WARRANTING A COLD WEATHER ADVISORY.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 100 AM TUESDAY: ARCTIC HIGH PRESSURE WILL SETTLE OVER THE
SOUTHEAST FRIDAY THRU SATURDAY, WITH DRY CONDITIONS EXPECTED. AS
THE AIR MASS MODERATES, TEMPS WILL START A WARMING TREND FROM
FRIDAY MORNING'S CHILLY START. HIGHS SHOULD REBOUND A FEW DEGREES
FROM THURSDAY'S READINGS, BUT STILL ABOUT 10 DEG BELOW NORMAL, THEN
JUST A FEW DEG BELOW NORMAL SATURDAY. A SHORTWAVE TROUGH WILL DIVE
SOUTHEAST ACROSS THE ROCKIES AND INTO THE SOUTHERN PLAINS, THEN
FLATTEN OUT AS IT MOVES INTO QUASI-ZONAL FLOW ACROSS THE EASTERN
CONUS BY LATE SATURDAY. THE GFS CONTINUES TO BE JUST A LITTLE DEEPER
WITH THE TROUGH AND TAPS INTO A LITTLE GULF MOISTURE FOR A QUICK
SHOT OF LIGHT PRECIP SUNDAY. TEMPS WOULD LIKELY BE WARM ENOUGH
FOR JUST RAIN, IF ANYTHING DEVELOPS OUTSIDE THE MOUNTAINS. BUT
A WINTRY MIX MAY BE POSSIBLE IN THE HIGH TERRAIN. THE ECMWF AND
CANADIAN ARE STILL DRY, AS IS THE MAJORITY OF THE GEFS AND GEPS
ENSEMBLES. SO WILL CONTINUE TO GO WITH THE NBM'S DRY FCST FOR
SUNDAY. DRY WX CONTINUES ACROSS THE AREA EARLY NEXT WEEK, WITH
TEMPS WARMING TO A FEW DEG ABOVE NORMAL.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS EXPECTED THROUGH TONIGHT. HIGH
PRESSURE SLOWLY BUILDS INTO THE AREA THROUGH THE PERIOD. PERIODS OF
MAINLY CIRRUS MOVE ACROSS THE AREA BUT SOME LOW ALTOCU OR HIGH
STRATOCU MAY MOVE ACROSS THE MOUNTAINS OR KHKY. LIGHT AND VARIABLE
OR LIGHT N WIND BECOMES LIGHT S FOR THE AFTERNOON THEN BACK TO LIGHT
NE OR LIGHT AND VARIABLE THIS EVENING. KAVL WILL SEE LIGHT N WIND
THROUGHOUT, BUT CAN'T RULE OUT SOME LIGHT SSE DURING THE AFTERNOON.
OUTLOOK: RESTRICTIONS WILL LIKELY RETURN TO THE AREA ON WEDNESDAY
WITH A MIX OF WINTRY WEATHER. DRY HIGH PRESSURE RETURNS LATE
THURSDAY AND LINGERS INTO THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...WINTER WEATHER ADVISORY FROM 6 AM WEDNESDAY TO NOON EST
THURSDAY FOR GAZ010.
NC...WINTER WEATHER ADVISORY FROM 6 AM WEDNESDAY TO NOON EST
THURSDAY FOR NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH
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