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000
FXUS62 KGSP 301435
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
935 AM EST FRI JAN 30 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE EAST OF THE AREA TODAY. COOL HIGH PRESSURE
WILL BUILD INTO THE REGION BEHIND THE FRONT TODAY AND LINGER THROUGH
MOST OF THE WEEKEND. MOISTURE SHOULD RETURN LATE IN THE WEEKEND
AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM...WITH THE ASSOCIATED COLD
FRONT CROSSING THE REGION EARLY MONDAY. COLD AND DRY HIGH PRESSURE
WILL THEN SET UP THROUGH THE FIRST HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM UPDATE...HAVE RAISED POPS INTO THE CATEGORICAL RANGE
OVER THE AVERY AND MITCHELL COUNTIES THIS MORNING TO ACCOUNT FOR THE
LATEST RADAR RETURNS AND LOCAL WEBCAMS. THE NW SNOW SHOULD GRADUALLY
TAPER OFF ALONG THE TN LINE COUNTIES THROUGH MIDDAY AS LLVL DRYING
OCCURS IN LIGHT OF DRY AND COLD HIGH PRESSURE BUILDING IN FROM THE
WEST.

AS OF 635 AM...A SHARP SHORTWAVE TROUGH WILL MOVE EAST OF THE
AREA THIS MRNG...WHILE ITS ASSOCIATED SFC LOW MOVES OFF THE
NORTHEAST COAST. COLD FRONT APPEARS TO HAVE CLEARED THE AREA ATTM.
TEMPS HAVE REMAINED WARMER THAN GUIDANCE THRU THE WEE HRS OF THE
MRNG...BUT COLD ADVECTION IS HAVING AN EFFECT NOW THAT MOST OF THE
CLOUDINESS HAS CLEARED. TEMPS SHOULD COOL A BIT MORE AFTER DAYBREAK
BEFORE THE SUN HAS A CHANCE TO WORK ITS MAGIC. BRISK NWLY FLOW WILL
SET IN TODAY BEHIND THE FRONT...AS A SEASONABLY STRONG CANADIAN
HIGH FILLS IN ACRS THE MISSISSIPPI VALLEY. THIS WILL LEAD TO SOME
UPSLOPE SNOWFALL NEAR THE TENN BORDER AS WELL AS VERY GUSTY WINDS.

POPS WERE UPDATED THRU THE MRNG PER CLOUD TOP TEMPS...WITH REPORTS
FROM THE TENN BORDER COUNTIES INDICATING SNOW FALLING FROM A SHALLOW
LAYER BENEATH RADAR BEAMS. THE SETUP FOR NW FLOW SNOW LOOKS BEST
EARLY THIS AM...MOISTURE PROFILES BECOMING MORE SHALLOW AS THE DAY
CONTINUES AS DRIER AIR ARRIVES WITH THE HIGH PRESSURE. IN FACT BY
LATE MRNG THERE IS NOT MUCH OF A SATURATED LAYER AT ALL. SNOW-LIQUID
RATIOS ARE NOT LIKELY TO BE HIGH GIVEN THE TOP OF THE LAYER BEING
JUST WITHIN THE PRIME NUCLEATION ZONE...SO TOTALS WILL BE BELOW ADVY
CRITERIA. SOME MINOR ROADWAY ISSUES COULD OCCUR ESP IN CONJUNCTION
WITH THE WINDS...SO WE HAVE MAINTAINED AN SPS TO HIGHLIGHT THE
POTENTIAL.

PRESSURE GRADIENT APPEARS STRONGEST PRIOR TO 18Z TODAY WITH GOOD
MIXING AFFORDED BY DRY DEWPOINTS AND DOWNSLOPE WARMING. GUSTS WILL BE
FREQUENT ACROSS THE PIEDMONT...BUT THE HIGHER TERRAIN WILL OF COURSE
MIX INTO STILL STRONGER WINDS FURTHER ALOFT. SYNOPTIC MODELS ARE IN
THE SAME BALLPARK AS FAR AS SUSTAINED WINDS...AND TAKING THESE VALUES
WITH GUST FACTORS DERIVED FROM BUFKIT SOUNDINGS WINDS MEET ADVISORY
CRITERIA IN PORTIONS OF THE NRN MTN ZONES EVEN BEFORE ANY
ELEVATION-BASED ENHANCEMENT IS APPLIED TO GUSTS. STILL THINK THE
PREVIOUS SHIFT/S DECISION TO INCLUDE A MENTION OF 60-PLUS MPH GUSTS
IN THE ELEVS ABV 5000 FT WAS REASONABLE...AND LATEST WSW FEATURES
THAT. WITH THE HIGH CONTINUING TO PUSH IN TONIGHT...AND BEING
BASICALLY OVERHEAD BY 12Z SAT...THE GUSTS SHOULD DIE DOWN GRADUALLY
THRU THE EVENING.

TEMPS TODAY WILL MAX OUT ABOUT 10 DEG BELOW CLIMO IN THE MTNS DUE TO
THE STRONG WINDS AND COLD ADVECTION...WHILE THE PIEDMONT WILL SEE
HIGHS JUST A COUPLE DEGREES BELOW NORMAL. TONIGHT...AS THINGS CALM
DOWN AND DRY DEWPOINTS PERSIST...LOWS WILL BE 6-8 DEGREES BELOW
NORMAL.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 230 AM FRIDAY...FLAT UPPER RIDGING WILL SETTLE ACROSS THE ERN
CONUS FROM THE W ON SATURDAY. WNW DOWNSLOPE FLOW WILL AID
TEMPERATURES DESPITE THE CHILLY THICKNESSES IN PLACE. EXPECT MAINLY
AN INCREASE IN MID AND HIGH CLOUDS SAT AFTN THROUGH SAT NIGHT.

REASONABLY GOOD MODEL AGREEMENT EXISTS ON A CLIPPER SYSTEM DIGGING
FROM THE NRN PLAINS TO THE MIDWEST SAT NIGHT THROUGH SUNDAY...
CROSSING THE APPALACHIAN CHAIN WITH AN ASSOCIATED COLD FRONT EARLY
MONDAY. THERMAL PROFILES ACROSS THE FORECAST AREA ARE MARGINALLY
COLD ENOUGH TO SUPPORT SOME WET SNOW AT ONSET SUNDAY...BUT THE
DEEPEST MOISTURE/FORCING AHEAD OF THE WAVE NOW LOOKS DELAYED UNTIL
LATE SUNDAY/SUNDAY NIGHT. WITH THE SFC LOW WITH THIS SYSTEM EXPECTED
TO PASS JUST N OF THE OUR FORECAST AREA...THICKNESSES SHOULD REMAIN
WARM ENOUGH FOR RAIN UNTIL WELL INTO SUNDAY EVENING. HOWEVER...SNOW
LEVELS WILL FALL QUICKLY FROM THE WEST SUNDAY NIGHT INTO MONDAY
MORNING ACROSS THE HIGHER TERRAIN. WITH DECENT MODEL QPF EXPECTED
DURING THE PERIOD OF ROBUST COLD ADVECTION AND NW FLOW...SOME
ADVISORY LEVEL ACCUMULATIONS COULD RESULT IN THE WRN MTNS BY MONDAY
MORNING. AN HWO MENTION SEEMS WARRANTED. EXPECT DRYING WITH BREEZY
TO WINDY CONDITIONS ON MONDAY. HOWEVER...SHALLOW MOISTURE WEST OF
THE SRN APPALACHIANS COULD CONTINUE TO WRING OUT SCATTERED NW FLOW
UPSLOPE SNOW SHOWERS THROUGH DAY.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 230 AM EST FRIDAY...ZONAL UPPER LEVEL FLOW WILL RETURN ON
TUESDAY...WITH ANY MID LEVEL MOISTURE PASSING N OF THE FORECAST
AREA. WITH CHILLY THICKNESSES IN PLACE...EXPECT PLENTY OF TEENS AND
LOWER 20S FOR TUE MORNING MINS...WITH AFTN MAXES 10 DEGREES OR MORE
BELOW CLIMO.

AN ACTIVE PATTERN WILL THEN QUICKLY GET REESTABLISHED MID TO LATE
WEEK. FORECAST CONFIDENCE IS QUITE LOW WED THROUGH THU AS BOTH SRN
STREAM ENERGY FROM THE GULF COAST AND AN AMPLIFYING NRN TIER TROUGH
WITH AN ASSOCIATED COLD FRONT COULD PROVIDE MOISTURE AND FORCING TO
THE AREA...BUT WITH CONSIDERABLE SPREAD IN THE TIMING AMONG THE
MODELS/MEMBERS. USING A CONSENSUS SOLUTION...THE SRN TIER WAVE AND
ASSOCIATED SFC FEATURE FROM THE GULF COAST MAY SPREAD PRECIP CHANCES
BACK INTO THE REGION ON WED. PROFILES GENERALLY LOOK WARM ENOUGH FOR
RAIN THROUGH MUCH OF THE WED/THU EVENT...BUT THE LOW PRESSURE
WRAPPING UP ALONG THE PASSING FRONTAL ZONE THROUGH THU COULD QUICKLY
TOGGLE MTN PRECIP BACK TO SNOW...DEPENDING ON THE TIMING. WILL
FEATURE MAINLY LOW END RAIN/SNOW CHANCES WITH BELOW CLIMO TEMPS FOR
WED/THU UNTIL FORECAST CONFIDENCE IMPROVES.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SOLIDLY NW WINDS WITH FREQUENT LOW-MODT GUSTS TODAY IN
COLD ADVECTIVE PATTERN IN THE WAKE OF THE EARLY MORNING FROPA.
CAN/T RULE OUT A COUPLE GUSTS ABOVE 30KT. LIGHTER NW WINDS AND
SKC TONIGHT UNDER BUILDING HIGH PRESSURE AND DRY SFC CONDITIONS.

ELSEWHERE...NW FLOW WILL DRIVE MTN PRECIP ALONG THE TENN BORDER
MUCH OF TODAY. PCPN CHANCES AT KAVL ARE TOO LOW TO MENTION BUT SOME
LIGHT SPRINKLES OR FLURRIES COULD OCCUR FROM TIME TO TIME VERY EARLY
IN THE PERIOD. FREQUENT GUSTS OF 20-25KT ACRS MUCH OF THE REGION
THIS AFTN...WITH THE MTNS GUSTING HIGHER. KAVL MIGHT EVEN SEE A
COUPLE GUSTS OF 35-40KT. INCOMING HIGH PRESSURE TONIGHT WILL ALLOW
WINDS TO RELAX AND SKIES TO REMAIN MCLR.

OUTLOOK...MAINLY VFR CONDITIONS ARE EXPECTED ACROSS THE AREA
SATURDAY. MOISTURE THEN BEGINS TO RETURN SUNDAY AHEAD OF ANOTHER LOW
PRESSURE SYSTEM...WHICH IS LIKELY TO BRING PRECIP AND RESTRICTIONS.
DRYING IS EXPECTED BY LATE MONDAY IN THE WAKE OF THAT SYSTEM.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  98%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...JOH/WIMBERLEY
SHORT TERM...HG
LONG TERM...HG
AVIATION...WIMBERLEY