733  
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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