Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 260550
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
150 AM EDT SAT JUL 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE AREA THROUGH THE WEEKEND.
ANOTHER COLD FRONT IS EXPECTED TO REACH THE AREA FROM THE NORTHWEST
BY EARLY MONDAY. HIGH PRESSURE WILL REGAIN CONTROL ON TUESDAY...
LASTING THROUGH AT LEAST MID-WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 150 AM...PATCHY FOG AND SOME LOW CLOUDS FORMING EVEN WITH THE
MID AND HIGH CLOUDS MOVING OVERHEAD. IF THESE CLOUDS DO NOT BECOME
THICKER...THEN FOG WILL BECOME MORE WIDESPREAD BY DAYBREAK. HAVE
ADDED FOG TO MUCH OF THE AREA...BUT LIMITED DENSE FOG TO THE MTN
VALLEYS. WILL HAVE TO KEEP A WATCH ON THIS THRU THE NITE.
OTHERWISE...FCST IS ON TRACK WITH UPDATES ONLY FOR CURRENT
CONDITIONS.

AS OF 945 PM EDT...THE LAST VESTIGES OF ISOLD SHOWERS ALONG THE NRN
BLUE RIDGE AND IMMEDIATELY ADJACENT FOOTHILLS SHOULD DISSIPATE
BEFORE MIDNIGHT. ALTHOUGH AN UPSTREAM MID LEVEL SHORTWAVE WILL LIKELY
CROSS THE NRN HALF OF THE FORECAST AREA OVERNIGHT...NO ADDITIONAL
PRECIPITATION IS EXPECTED AS PROFILES CONTINUE TO STABILIZE.
HOWEVER...THIS FEATURE SHOULD BE ACCOMPANIED BY AN INCREASE IN MID
AND HIGH LEVEL CLOUDINESS WHICH COULD IMPACT FOG AND LOW CLOUD
FORMATION IN THE MOIST SFC LAYER. THE CURRENT THINKING IS THAT THE
HIGHER CLOUDS WILL BE MAINLY THIN AND PROBABLY ALLOW AT LEAST LIGHT
FOG TO DEVELOP IN PATCHES ACROSS THE NRN TIER...WITH THICKER FOG AND
LOW STRATUS IN THE MTN VALLEYS...ESPECIALLY IN SW SECTIONS...THROUGH
THE EARLY MORNING HOURS. THE LACK OF PRECIPITATION TODAY...THE
VEERED LIGHT SW SFC FLOW...AND THE PATCHY MID AND HIGH CLOUDS SHOULD
PRECLUDE DENSE FOG CONCERNS OVER THE FOOTHILLS AND PIEDMONT TOWARD
DAYBREAK. MIN TEMPS APPEAR ON TRACK FOR NEAR CLIMO VALUES.

SATURDAY...FORECAST SOUNDINGS ARE CAPPED UNDER THE INFLUENCE OF
RISING HEIGHTS ALOFT...AS A RIDGE AXIS ASSOCIATED WITH THE
SUBTROPICAL HIGH OVER THE GREAT PLAINS NOSES ITS WAY TOWARD THE
SOUTHEAST COAST. AS A RESULT...THERE IS LITTLE TO NO MODEL QPF
RESPONSE ACROSS THE AREA SAT AFTERNOON...AND A DRY FORECAST WILL BE
MAINTAINED. OTHERWISE...TEMPS WILL WARM NOTICEABLY FROM TODAY/S
READINGS...WITH MAXES EXPECTED TO REACH THE LOWER 90S IS MOST
LOCATIONS EAST OF THE MTNS...AND MID/UPPER 80S EXPECTED IN THE MTN
VALLEYS.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 100 PM FRI...BROADLY CYCLONIC UPPER LEVEL FLOW WILL CONTINUE
ACRS THE ERN HALF OF THE CONUS SATURDAY NIGHT AND SUNDAY...BEFORE
BEGINNING TO AMPLIFY MONDAY AS A POTENT SHORTWAVE MOVES THRU THE
GREAT LAKES. A COLD FRONT ACCOMPANYING THE TROUGH WILL MOVE THRU THE
OHIO VALLEY SUNDAY...WITH MOST GUIDANCE INDICATING A PASSAGE ACRS THE
SRN APPALACHIANS EARLY MONDAY...BUT STILL IN PLACE TO AFFECT THE
PIEDMONT THAT AFTN.

SATURDAY NIGHT SHOULD BE QUIET WITHIN OUR CWFA...AND SUNDAY SHOULD
START OFF QUIET. VARIOUS GUIDANCE SOURCES CONTINUE TO SHOW NOTABLE
DIFFERENCES IN QPF RESPONSE TO DIURNAL DESTABILIZATION. GFS IS
ESSENTIALLY THE DRIEST MODEL...WITH A WARM LAYER ALOFT CAPPING OFF
CONVECTION. OPNL NAM ALSO INDICATES SOME DEGREE OF CAPPING THOUGH IT
WEAKENS LATE IN THE DAY...PARTICULARLY OVER THE MTNS. SREF MEMBERS
ARE FAIRLY EVENLY SPREAD BETWEEN STRONG CAPPING AND FREE CONVECTION.
LAPSE RATES ABOVE THE WARM LAYER ARE DECENT...WHICH IN CONJUNCTION
WITH SFC TEMPS/DEWPTS SLIGHTLY ABOVE NORMAL MEANS UNCAPPED PARCELS
WILL BE SOMEWHAT MORE UNSTABLE THAN USUAL. THIS WOULD BE CONCURRENT
WITH STRENGTHENING UPPER FLOW AHEAD OF THE DIGGING TROUGH...SO IF THE
TIMING IS RIGHT THERE COULD BE A SEVERE THREAT. THIS BECOMES MORE OF
A CONCERN OVERNIGHT IN THE MTNS WHERE SOME PROG SOUNDINGS ARE
UNCAPPED FOR NEAR-SURFACE PARCELS AS SHEAR RISES TO 40-50 KT. SPC HAS
ALREADY INCLUDED A PORTION OF OUR MTNS IN A SLIGHT RISK ON THE DAY 3
OTLK VALID THRU 12Z MON...WITH MOST OF THE REST OF THE CWFA WITHIN
THE 5 PERCENT CONTOUR. REGARDLESS OF ANY CONVECTION...WINDS WILL
BEGIN TO BECOME RATHER GUSTY IN THE HIGHER ELEVATIONS SUNDAY NIGHT.
THIS WILL CONTINUE MONDAY EVEN POST-FROPA.

COOLER AND DRIER AIR ARE PROGGED TO BEGIN FILTERING INTO THE MTNS BY
MIDDAY MONDAY...AND THRU THE PIEDMONT BY 00Z TUE IN THE WAKE OF THE
FRONT. THERE STILL APPEARS TO BE TIME FOR DESTABILIZATION AHEAD OF
THE WIND SHIFT LINE SO FRONTAL ENHANCEMENT TO TSTM CHANCES APPEARS
LIKELY AT LEAST ALONG AND SOUTH OF I-85 IF NOT UP INTO THE FOOTHILLS.
HODOGRAPHS IN THIS AREA WILL BE RATHER LONG WITH H5 FLOW NEARING 50
KT INDICATING A SUPERCELL RISK IN OUR AREA. SPC IS CURRENTLY
HIGHLIGHTING AREAS OF ERN NC/VA ON THE DAY 4 GRAPHIC BUT THE RISKS
THEY DESCRIBE APPEAR TO BE PRESENT IN OUR ERN/SERN ZONES AS WELL.
MONDAY AFTN MAX TEMPS IN THE MTNS REFLECT THE COOL AIRMASS THAT WILL
REMAIN OVER THE REGION THRU MOST OF NEXT WEEK...BEING 2 OR 3
CATEGORIES BELOW NORMAL. THE PIEDMONT APPEARS TO STILL BE CAPABLE OF
MAXES NEAR NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 2 PM EDT FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
TUESDAY WITH A SIGNIFICANT UPPER TROF DIGGING DOWN OVER THE EASTERN
CONUS WHILE AN EQUALLY STEEP UPPER RIDGE IS IN PLACE OVER THE WEST.
NO MAJOR PATTERN CHANGES ARE EXPECTED AS THIS TROF WILL REMAIN
LARGELY IN PLACE THRU DAY 7 WITH SOME DEAMPLIFICATION LIKELY ON DAYS
6 AND 7.

AT THE SFC...A FAIRLY STRONG WARM SEASON COLD FRONT WILL BE MOVING
THRU THE FCST AREA LATE MON/EARLY TUES WITH CONSIDERABLY COOLER AND
DRIER AIR SPREADING OVER THE CAROLINAS ON TUES. BEHIND THE DEPARTING
FRONT CANADIAN HIGH PRESSURE WILL KEEP NLY FLOW OVER THE AREA THRU
WED AS IT GRADUALLY SLIDES SOUTHEASTWARD. BY THURS...BNDRY LYR FLOW
SHOULD BE PRETTY WEAK AND POSSIBLY BECOME VRB FOR MOST OF THE
DAY/EVENING. ON FRI...THE LONG RANGE MODELS VEER THE LOW LVL FLOW
MORE FROM THE EAST TO NE AND MOVE A LARGE PLUME OF DEEPER LYR
MOISTURE OVER THE CWFA FROM THE SOUTH. THIS WILL PROVIDE OUR BEST
OPPORTUNITY FOR WIDESPREAD SHOWERS AND TS IN THE MEDIUM RANGE.
OTHERWISE...I EXPECT DRY CONDITIONS WITH UNSEASONABLY COOL TEMPS
THRU DAY 7.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE EXCEPT KAVL...THE LOW CLOUDS FROM EARLIER HAVE
MOVED EAST OF THE AREA. GUIDANCE DOES NOT SHOW THE LOW CLOUDS MOVING
BACK INTO THE AREA AS LOW LEVEL FLOW IS S TO SW. THAT SAID...CANNOT
COMPLETELY RULE OUT STRATUS RETURNING FROM THE EAST. HOWEVER...THERE
WILL BE QUITE A BIT OF DEBRIS CLOUDINESS MOVING OVER THE AREA FROM
THE NW. THIS COULD KEEP FOG FORMATION TO THE NORMALLY MORE FOGGY
AREAS. AGAIN...THERE COULD BE QUITE A BIT MORE FOG THAN THAT. ANY
RESTRICTIONS THAT DO DEVELOP SHUD QUICKLY DISSIPATE AFTER DAYBREAK.
LIGHT S TO SW WINDS BECOME CALM OVERNIGHT WITH SWLY WINDS DEVELOPING
WITH MIXING AND CONTINUING INTO THE EVENING. EXPECT SOME HIGH BASED
CU DEVELOPING DURING THE AFTERNOON AS WELL.

AT KAVL...PLENTIFUL LOW LEVEL MOISTURE WILL THEN MEAN THAT FOG AND
LOW STRATUS ARE IN STORE FOR THE EARLY MORNING HOURS. HOWEVER...ANY
THICKER MID AND HIGH CLOUDS WITH THE PASSING SHORTWAVE COULD TEMPER
THIS SOMEWHAT...BUT WITH RESTRICTIONS ALREADY FORMING...THEY MAY NOT
KEEP IFR FROM DEVELOPING. ANY RESTRICTIONS SHUD DISSIPATE BEFORE MID
MORNING WITH CU DEVELOPING THRU THE DAY. CALM WIND OVERNIGHT BECOMES
NLY DURING THE MORNING THEN SLY FOR THE AFTERNOON.

OUTLOOK...SCT THUNDERSTORMS MAY RETURN TO THE FORECAST AREA SUNDAY
AFTERNOON THROUGH MON AS ANOTHER COLD FRONT APPROACHES AND THEN
MOVES THROUGH THE AREA BY MON NIGHT. VFR CONDITIONS WILL THEN LINGER
THROUGH MID WEEK.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH  92%     HIGH  92%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  94%     HIGH  94%     HIGH 100%     HIGH 100%
KHKY       HIGH  93%     HIGH  95%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  96%     HIGH  93%     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...NONE.
SC...NONE.

&&

$$
SYNOPSIS...JDL
NEAR TERM...HG/RWH
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...RWH





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