Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 300830
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
330 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 315 AM...A COLD FRONT SHOULD HAVE PUSHED THROUGH MOST IF NOT
ALL OF OUR PIEDMONT ZONES BY DAYBREAK. THIS ASSOCIATED WITH A SHARP
SHORTWAVE TROUGH AND LOW PRESSURE MOVING OFF THE NORTHEAST COAST. LOW
CLOUDINESS INVOF THE FRONTAL CONVERGENCE ZONE APPEARS TO BE RESISTING
EROSION BY THE DOWNSLOPE FLOW...AND AT LEAST SOME OF THE AREA SEEMS
LIKELY TO REMAIN UNDERNEATH CLOUD COVER THRU DAYBREAK. REVISED TEMPS
ARE SEVERAL DEGREES WARMER THAN PREV FCST...THE COLD ADVECTION NOT
HAVING AS MUCH OF AN IMPACT DUE TO THE CLOUDS.

BRISK NWLY FLOW WILL SET IN TODAY AS A SEASONABLY STRONG CANADIAN
HIGH FILLS IN ACRS THE MISSISSIPPI VALLEY. THE SENSIBLE WX CONCERNS
FOR THE NEAR TERM ARISE FROM THE NW FLOW...THE CONCERNS BEING STRONG
WINDS AND /TO A LESSER EXTENT/ UPSLOPE SNOWFALL NEAR THE TENN BORDER.

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.

REGARDING THE SNOW...THE SETUP LOOKS MOST CAPABLE OF ACCUMULATION
EARLY THIS AM BEFORE MOISTURE PROFILES BECOME SHALLOW 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.

&&

.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 /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT...GUIDANCE SUGGESTS FROPA WILL OCCUR EARLY THIS AM...BUT
ALREADY SEEMS A LITTLE TOO FAST WITH TIMING OF WSHFT. NO PRECIP
EXPECTED TO MAKE IT THIS FAR EAST OF THE MTNS IN DOWNSLOPING FLOW
ALOFT. WINDS SHOULD BEGIN TO FAVOR NWLY AFTER 08Z WITH SOLIDLY NW
WINDS NOT ARRIVING UNTIL A LITTLE LATER. A MIDLEVEL CIG WILL LIKELY
PERSIST UNTIL AFTER SUNRISE UNLESS DOWNSLOPING IS MORE EFFECTIVE
THAN ANTICIPATED. NW WINDS WITH FREQUENT LOW-END GUSTS AS SOON AS
MIXING BEGINS TODAY. CAN/T RULE OUT A COUPLE GUSTS TO NEAR 30KT
THOUGH. GENERALLY CALMER AND CONTINUED CLEAR TONIGHT UNDER BUILDING
HIGH PRESSURE AND DRY SFC CONDS.

ELSEWHERE...A LOW VFR CIG WILL PERSIST THRU THE EARLY AM DUE TO
MIDLEVEL MOISTURE AND ENHANCED LIFT FROM FROPA. NW FLOW WILL DRIVE
MTN PRECIP ALONG THE TENN BORDER. PCPN CHANCES AT KAVL ARE TOO LOW
TO MENTION BUT SOME LIGHT SPRINKLES OR FLURRIES COULD OCCUR.
GUIDANCE HAS BACKED OFF EARLIER EXPECTATION OF AN MVFR CIG AT KAVL
BUT A FEW CLOUDS AT THAT LEVEL ARE LIKELY TO BE SEEN. WSHFT TO NW
WILL OCCUR POST FROPA GENERALLY IN THE 08-10Z TIMEFRAME WITH THE
CIGS SCOURING IN THE WAKE OF THE FRONT...THOUGH CIGS MAY NOT CLEAR
COMPLETELY UNTIL AFTER DAYBREAK. FREQUENT GUSTS OF 20-25KT ACRS MUCH
OF THE REGION THIS AFTN...WITH THE MTNS GUSTING HIGHER. KAVL MIGHT
SEE SOME GUSTS OF 30-35KT. 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...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  89%     LOW   56%     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...WIMBERLEY
SHORT TERM...HG
LONG TERM...HG
AVIATION...WIMBERLEY


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