659
FXUS62 KGSP 190853
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
353 AM EST SUN JAN 19 2025
SYNOPSIS
A ROUND OF SNOW SHOWERS WILL DEVELOP THIS MORNING NEAR THE TENNESSEE
BORDER AND LINGER THROUGH MONDAY MORNING, WITH GOOD SNOW ACCUMULATION
LIKELY AT THE HIGHER ELEVATIONS. ARCTIC HIGH PRESSURE MOVING IN TONIGHT
WILL BRING BITTER COLD TO THE REGION FOR MOST OF THIS WEEK. A STORM
SYSTEM IS EXPECTED TO TRACK FROM THE NORTHERN GULF OF MEXICO TO OFF
THE SOUTHEAST COAST MID-WEEK, BRINGING THE POTENTIAL FOR SNOW SHOWERS
ACROSS PORTIONS OF THE AREA.
NEAR TERM /THROUGH TONIGHT/
AS OF 340 AM: UPPER TROUGH AXIS AND STRONG COLD FRONT, BOTH
ASSOCIATED WITH APPROACHING ARCTIC AIRMASS, REMAIN OFF TO THE
WEST. LOW STRATUS IS IN PLACE ACROSS THE GREATER I-85 CORRIDOR
AND POINTS SOUTH, WITH ONGOING WEAK WARM UPGLIDE NORTH OF A
STALLED FRONTAL BOUNDARY, AIDED BY WEAK SFC LOW IN AL/GA. AN AREA
OF CLEARER SKY IS PRESENT NORTH OF THAT STRATUS DECK, EXTENDING
ACROSS THE FOOTHILLS OF ALL THREE OF OUR STATES. AREAS OF DENSE
FOG ARE PRESENT BOTH UNDER THE STRATUS DECK AND ALSO IN THE RIVER
VALLEYS OF THE FOOTHILLS AND NW NC PIEDMONT. DENSE FOG ADVISORY
ISSUED AND VALID UNTIL 11 AM OWING TO STRENGTH OF INVERSION; MAY
BE CANCELLED A BIT EARLY BUT KEPT GOALPOSTS WIDE FOR SIMPLICITY
AS COMPLEX WX SITUATION UNFOLDS THIS MORNING.
THE SURFACE LOW WILL RIDE NORTHEAST ACROSS THE CAROLINAS TODAY,
PROGGED TO REACH THE TIDEWATER REGION BY LATE AFTERNOON. WARM
UPGLIDE WILL AMPLIFY AND LIGHT PRECIP MAY BE CARRIED NORTH INTO
THE I-85 CORRIDOR BY 6-7 AM. A VERY SMALL AMOUNT OF ELEVATED
INSTABILITY WILL BE PRESENT ABOVE THE INVERSION AND SOME SHOWERS
MAY DEVELOP FURTHER NORTH IN THE NC PIEDMONT BETWEEN DAYBREAK
AND ABOUT NOON. TEMPERATURES WILL BE PRETTY STEADY NEAR CURRENT
READINGS, WARMING SLOWLY ONCE THE SUN COMES UP, SO THIS WILL
BE ALL RAIN. SKIES WILL CLEAR AS THE LOW PASSES AND DOWNSLOPE
FLOW IS INDUCED ACROSS THE PIEDMONT FROM MIDDAY ONWARD. TEMPS
STILL WILL BE NEAR CLIMO IN THE SOUTHEASTERN CWA. HOWEVER, AS
WINDS TURN WESTERLY OVER THE MOUNTAINS THIS MORNING AS THE LOW
PASSES BY, CAA WILL BEGIN WHICH WILL STRENGTHEN THIS AFTERNOON,
AND UPSLOPE FORCING ALSO BEGINS. PROFILES QUICKLY COOL AND SNOW
LEVELS FALL IN THE TN/NC BORDER AREA, SUCH THAT ACCUMULATING SNOW
IS LIKELY TO BEGIN BY ABOUT 9-10 AM; RATES ARE EXPECTED TO PICK
UP APPRECIABLY DURING THE AFTERNOON AS WINDS ORIENT MORE NW. AREAS
ALONG THE TN BORDER WILL SEE THEIR DAYTIME HIGHS WELL BEFORE NOON,
WITH VALLEYS SEEING TEMPS FALL THROUGH THE AFTERNOON. AS NOTED BY
PREVIOUS FORECASTERS, THE UPSLOPE LAYER BECOMES ESPECIALLY COLD
SUPPORTING MUCH GREATER SNOW RATIOS THAN WE TYPICALLY SEE, LIKELY
APPROACHING 20 TO 1. SMALL SBCAPE IS DEPICTED ALONG THE TN BORDER
WHICH WILL HELP ENHANCE PRECIP PRODUCTION. RATES UP TO AROUND AN
INCH PER HOUR MAY OCCUR IN SOME VERY HIGH ELEVATIONS OF THE SMOKIES
THIS AFTERNOON; BEST ICE NUCLEATION OCCURS AFTER SUNSET ALTHOUGH BY
THEN MOISTURE BECOMES A BIT HARDER TO COME BY. RETAINED EXISTING
WINTER STORM WARNINGS AND ADVISORIES. SUSTAINED WINDS OF 10 TO 20
MPH, WITH GUSTS OF UP TO 40 MPH MAY OCCUR ON RIDGETOPS, AND BASED
ON EXPECTED LOWS IN THE SINGLE DIGITS ACROSS MOST OF THE MOUNTAINS
(BELOW ZERO ON HIGHER RIDGETOPS, AND 10-15 IN THE FOOTHILLS),
WIND CHILLS EASILY MEET PREVIOUS EXPECTATIONS OF COLD WX ADVISORY
CRITERIA IN VALLEYS/FOOTHILLS AND EXTREME COLD WARNING IN HIGHER
ELEVATIONS. ALL AREAS PREVIOUSLY IN EXTREME COLD WATCH ARE NOW IN
ONE OF THOSE PRODUCTS; ADVISORY CRTIERIA LOOK TO BE MET IN SOME
ADJACENT FOOTHILLS AREAS SO THAT WAS ADDED WITH THIS ISSUANCE. WE
MISS CRITERIA BY ONLY A FEW DEGREES ELSEWHERE IN THE FORECAST AREA
ALTHOUGH THE INDICATION IS THAT ACCUMS MIGHT ONLY BE ON THE ORDER OF
1-3 INCHES IN THE TN BORDER COUNTIES AWAY FROM THE UPSLOPE AREAS,
THE DRY SNOW FALLING INTO TEMPS BELOW THE UPPER 20S SHOULD RESULT
IN VERY SLIPPERY ROAD CONDITIONS IN PLACES WHERE ROADS ARE NOT
TREATED. THIS COULD RESULT IN A HIGH IMPACT TO TRANSPORTATION.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
AS OF 3:25 AM EST SUNDAY...THE SHORT-TERM FCST PICKS UP AT 12Z ON
MONDAY WITH VERY BROAD UPPER TROFING COVERING MOST OF THE CONUS.
OVER THE NEXT 24 HRS OR SO, THE TROF BEGINS TO SHIFT EAST AND DE-
AMPLIFY AS UPPER RIDGING BUILDS OVER THE WEST COAST. TOWARDS THE
END OF THE PERIOD EARLY WEDNESDAY, THE TROF AXIS IS EXPECTED TO
PASS OVER OUR AREA AND THEN LIFT NE AND OFF THE ATLANTIC COAST.
AT THE SFC, BROAD, ARCTIC HIGH PRESSURE WILL BE SPREADING OVER
THE SOUTHEAST AS THE PERIOD BEGINS. THE HIGH WILL LINGER OVER OUR
AREA INTO TUESDAY AND THEN GET REINFORCED FROM THE WEST TOWARDS
THE END OF THE PERIOD LATE TUESDAY INTO EARLY WEDNESDAY. AT THE
SAME TIME, A LOW IS PROGGED TO DEVELOP OVER THE GULF OF MEXICO
AND THEN QUICKLY MOVE NE AND OUT OVER THE ATLANTIC. WITH THE COLD
AIR IN PLACE DURING THAT TIME, IT'S STILL LIKELY THAT ANY PRECIP
THAT DOES MATERIALIZE WOULD BE SNOW FOR OUR FCST AREA. OVERALL,
PRECIP CHANCES HAVE TRENDED UP A BIT ROUGHLY ALONG AND SOUTH OF
THE I-85 CORRIDOR, BUT THE QPF AMOUNTS REMAIN MINIMAL AT BEST
WITH ONLY A FEW HUNDRETHS OF AN INCH EXPECTED FOR OUR FCST AREA.
NONETHELESS, THIS DOES PRODUCE ABOUT A HALF INCH OF SNOW OVER
OUR SOUTHERN/SOUTHEASTERN-MOST ZONES LATE TUES INTO EARLY WED.
WITH THE COLD SFC/ROAD TEMPS ALREADY IN PLACE, ANY SNOWFALL COULD
PRODUCE SIGNIFICANT IMPACTS ON UNTREATED ROADS. THE OTHER MAIN
CONCERN FOR THE PERIOD WILL BE THE VERY COLD AIRMASS THAT LINGERS
THRU THE PERIOD. THIS AIRMASS WILL PRODUCE VERY COLD TEMPERATURES
AND WIND CHILLS, ESPECIALLY ACROSS THE MTNS. HIGH TEMPERATURES WILL
STRUGGLE TO GET ABOVE FREEZING EACH DAY ACROSS MOST OF OUR CWA.
WINDS ARE EXPECTED TO BE GUSTY AS THE PERIOD BEGINS MONDAY MORNING,
WHICH WILL LIKELY PRODUCE WIND CHILL VALUES BELOW ZERO ACROSS MOST
OF THE MTNS EARLY MONDAY WITH SINGLE DIGIT TO LOW TEENS LIKELY FOR
MOST OF OUR LOWER TERRAIN. WIND CHILL VALUES AREN'T EXPECTED TO BE
AS LOW TUESDAY MORNING AS WINDS SHOULD BE WEAKER, HOWEVER WINDS PICK
UP AGAIN EARLY WEDNESDAY MORNING AND PRODUCE ANOTHER ROUND OF VERY
COLD WIND CHILLS EARLY WEDNESDAY.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
AS OF 3:05 AM EST SUNDAY...THE EXTENDED FCST PICKS UP AT 12Z ON
WEDNESDAY WITH BROAD UPPER TROFING FLATTENING OVER OUR AREA AND
HEIGHTS BRIEFLY RECOVERING. OVER THE NEXT COUPLE OF DAYS, THE
BACKSIDE OF THE TROF WILL AMPLIFY AGAIN OVER THE CENTRAL CONUS
AND THEN TRANSLATE EAST AND OVER OUR REGION. BY EARLY SATURDAY,
MOST OF THE CURRENT LONG-RANGE GUIDANCE HAS THE UPPER TROF LIFT-
ING OFF THE ATLANTIC COAST WITH FLAT UPPER RIDGING SPREADING OVER
THE SOUTHEAST TO END THE PERIOD. AT THE SFC, A MOIST FRONTAL BOUN-
DARY IS EXPECTED TO BE LINGERING JUST TO OUR SOUTH AND EAST AS THE
PERIOD BEGINS EARLY WEDNESDAY. AT THE SAME TIME, HIGH PRESSURE GETS
REINFORCED FROM THE WEST ACROSS OUR FCST AREA AND LINGERS WELL INTO
THURSDAY. BY LATE THURSDAY, MOST OF THE LONG-RANGE GUIDANCE STILL
TRIES TO DEVELOP ANOTHER SFC LOW JUST OFF THE SE COAST AND THEN
QUICKLY MOVE THE SYSTEM NORTHWARD AND UP THE ATLANTIC COAST. HOW
FAST THIS HAPPENS STILL REMAINS UNCLEAR AMONGST THE OPERATIONAL
MODELS. AT THE SAME TIME, ANOTHER TRAILING COLD FRONT IS EXPECTED
TO MOVE THRU OUR AREA FROM THE WEST, BUT IT'S LOOKING PRETTY DRY
AT THIS POINT. IN ITS WAKE, ANOTHER BROAD AREA OF HIGH PRESSURE
WILL SPREAD BACK OVER THE SOUTHEAST TO END THE PERIOD. AS SUCH,
THE PERIOD REMAINS DRY THRU THE END OF THE WEEK WITH SOLID CHANCE
POPS BY THE VERY END OF THE PERIOD NEXT SUNDAY. THE COLD AIRMASS
WILL STILL BE IN PLACE AS THE PERIOD BEGINS, BUT WILL GRADUALLY
MODIFY AS THE PERIOD WEARS ON. TEMPS ARE STILL EXPECTED TO REMAIN
WELL-BELOW CLIMATOLOGY THRU FRIDAY, BUT SHOULD WARM TO NEAR-NORMAL
VALUES OVER THE WEEKEND AS THE PERIOD ENDS.
AVIATION /09Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: LOW STRATUS DECK OVER KCLT AND KGSP/KGMU/KAND
WILL REMAIN LOCKED IN UNTIL AROUND MIDDAY TODAY; SOME VARIABILITY
BETWEEN LIFR/IFR/MVFR POSSIBLE IN THE FIRST COUPLE HOURS OF THE
PERIOD BUT IS EXPECTED TO SETTLE TO LIFR THEREAFTER. GUIDANCE
SUGGESTS SOME AREAS UNDER THE DECK WILL DEVELOP DENSE FOG WHICH
COULD BRING ANY OF THOSE SITES BELOW MINIMA AT LEAST FOR SHORT
PERIODS; CHANCE AT KGMU IS ENOUGH TO WARRANT TEMPO. FOR KHKY/KAVL
CONFIDENCE IS LOWER ON FLIGHT CAT INITIALLY, WITH CLEARER
SKIES ALLOWING RADIATION FOG/STRATUS, BUT SO FAR HAVING PROVEN
INTERMITTENT. EXPECTATION IS THEY TOO WILL GO SOLIDLY LIFR TOWARD
DAWN, ALSO WITH SOME CHANCE OF DENSE FOG CAUSING THEM TO GO BELOW
MINIMA. WEAK SFC LOW WILL PASS NE'WD FROM CURRENT LOCATION OVER
AL/GA TO COASTAL NC/VA BY LATE AFTERNOON. THIS MAY ENHANCE WAA
WITHIN SFC BASED MOIST LAYER AND PRODUCE LIGHT -SHRA AT THE SC
SITES OR KCLT IN THE PREDAWN TO MID-MORNING PERIOD, BUT CHANCE
AND POTENTIAL IMPACT SMALL ENOUGH NO MENTION IS MADE. WINDS
INITIALLY LIGHT/VRB AND POSSIBLY BACKING IN ADVANCE OF THE SFC
LOW, BUT SHOULD RESPOND TO STRONG FRONT/TROUGH MOVING IN FROM
THE WEST LATE MORNING. SW WINDS AND GUSTS WILL DEVELOP IN LATE
MORNING THEN TURN NW AS LOW DEPARTS; LOW CLOUDS SHOULD BE SCOURED
OUT BY 18Z AND 20-30 KT GUSTS WILL CONTINUE THE REST OF THE DAY,
AND POSSIBLY THRU THE END OF THE PERIOD. LOW VFR TO MVFR CLOUDS
WILL PERSIST AT KAVL VIA UPSLOPE INTO THE MTN SPINE, AND A FEW
FLURRIES ARE NOT OUT OF THE QUESTION BUT LIKELY OF SMALL IMPACT.
OUTLOOK: GUSTY NW WINDS LINGER AT KAVL THROUGH MONDAY. AN ARCTIC
AIRMASS WILL SPREAD OVER THE REGION SUNDAY NIGHT, LINGERING MUCH
OF THE WEEK, BRINGING EXCEPTIONALLY COLD TEMPERATURES BUT MOSTLY
VFR. THERE IS A SMALL POTENTIAL FOR SNOW TUESDAY EVENING INTO
TUESDAY NIGHT BUT CONFIDENCE REMAINS LOW.
CLIMATE
RECORDS FOR 01-20
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 69 1906 24 2009 53 1954 -13 1985
1890
KCLT 71 1951 30 1983 53 1890 -2 1985
1929 1893
1927
KGSP 72 1933 30 1983 56 1922 1 1985
RECORDS FOR 01-21
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 72 1927 8 1985 59 1927 -16 1985
KCLT 73 1935 24 1985 58 1954 -5 1985
KGSP 73 1927 26 1985 59 1933 -4 1985
RECORDS FOR 01-22
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 73 1932 21 1960 59 1933 0 1970
KCLT 74 1937 29 1970 60 1906 5 1970
KGSP 72 1938 31 1970 58 1933 3 1893
1921
RECORDS FOR 01-23
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 73 1927 20 2005 54 1999 1 1936
1936
KCLT 75 1927 27 1970 59 1999 9 2003
KGSP 73 1974 30 1970 58 1999 5 1893
1927
GSP WATCHES/WARNINGS/ADVISORIES
GA...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR GAZ010-017-
018-026-028-029.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST MONDAY
FOR GAZ010-017-018-026.
NC...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR NCZ033-
035>037-048>053-056>059-062>065-068>072-082-501>510.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST MONDAY
FOR NCZ033-048>053-058-059-062>065-501>510.
WINTER STORM WARNING FROM 7 AM THIS MORNING TO 7 AM EST MONDAY
FOR NCZ033-048>052-058.
EXTREME COLD WARNING FROM MIDNIGHT TONIGHT TO NOON EST MONDAY
FOR NCZ033-048>052-058-059-062-063.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 AM EST
MONDAY FOR NCZ051-058-059.
SC...DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR SCZ008>014-
019-101>109.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST MONDAY
FOR SCZ101>103.
SYNOPSIS...WIMBERLEY
NEAR TERM...PM/WIMBERLEY
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...WIMBERLEY
CLIMATE...
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