Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 220550
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
150 AM EDT MON SEP 22 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION FROM THE NORTHWEST TONIGHT
BRINGING COOLER AIR TO THE REGION FOR THE UPCOMING WEEK. COOL AND
DRY CONDITIONS ARE LIKELY TO PERSIST FOR THE REST OF THE WORK
WEEK...WITH RAIN CHANCES INCREASING OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM EDT...THE LATEST SFC ANALYSIS SHOWS A COLD FRONT
STRETCHING FROM GSO TO GSP TO NEAR GVL. SHOWER COVERAGE ALONG AND
THE AHEAD OF THE BOUNDARY REMAINS SPOTTY AT BEST...AND POST FROPA NW
FLOW INTO THE NC MTNS HAS GENERATED LOWER CLOUDS BUT LITTLE TO NO
RETURNS ON RADAR. WILL FEATURE MAINLY ISOLD POPS FOR LIGHT SHRA FOR
A FEW HOURS EARLY THIS MORNING AND THEN DWINDLE IT THROUGH DAYBREAK.

ALTHOUGH DEEP LAYER DRYING IS EXPECTED BEHIND THE FRONT TODAY...A
POTENT H5 SHORTWAVE CURRENTLY DROPPING INTO THE LOWER OH VALLEY IS
EXPECTED TO ROUND THE ERN TROUGH AND CROSS THE FORECAST AREA THIS
AFTERNOON. IT WILL SHARPEN UP AS IT MOVES TOWARD THE BASE OF THE SRN
APPALACHIANS...GENERATING STRONG 850 TO 500 DPVA ALONG WITH LAPSE
RATES BETTER THAN 6.5 DEG C/KM ACROSS THE SRN TIER THIS AFTERNOON.
DRYING IS EXPECTED TO GENERALLY WIN OUT ACROSS OUR FORECAST
AREA...BUT ISOLD SHRA POPS WILL BE FEATURED ACROSS THE EXTREME SRN
PIEDMONT MID TO LATE AFTN. OTHERWISE...COOLING AND DRYING N TO NE
FLOW COULD PRODUCE SOME LOW END GUSTS AT TIMES THROUGH THE
DAY...WITH TEMPS SLIGHTLY BELOW CLIMO.

MOST NUMERICAL MODELS SHOW THE UPPER SHORTWAVE SLOWING DOWN AND
CLOSING OFF OVER THE LOWER PIEDMONT OR SC MIDLANDS TONIGHT. ANY
RESIDUAL MOISTURE IS EXPECTED TO BE EAST OF THE FORECAST AREA AND NO
FURTHER POPS WILL BE MENTIONED AS SPRAWLING 1024 MB HIGH PRESSURE
BUILDS FROM THE MIDWEST TO THE ERN SEABOARD OVERNIGHT. JUST ENOUGH
OF A PRES GRADIENT S OF THE SFC HIGH WILL LINGER THROUGH THE EARLY
MORNING HOURS TO PREVENT IDEAL RADIATING CONDITIONS. STILL...EXPECT
THE FIRST MORNING OF AUTUMN TO FEATURE MIN TEMPS IN THE UPPER 30S IN
SOME MOUNTAIN LOCATIONS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 130 PM EDT SUNDAY...THE SHORT TERM FORECAST PERIOD INITIALIZES
MONDAY EVENING WITH A SURFACE COLD FRONT TO THE SOUTH ACROSS THE LOW
COUNTRY WHILE A SHARP UPPER TROF AXIS SLIDES THOUGH THE SOUTHEAST
AND MID ATLANTIC.  HIGH PRESSURE WILL SPILL INTO NORTHEAST GA AND
THE WESTERN CAROLINAS THROUGH MONDAY NIGHT INTO TUESDAY LEADING TO A
DRY/COOL FORECAST.  ON TUESDAY...THE UPPER PATTERN FEATURES RISING
HEIGHTS WITH ABOVE MENTIONED CANADIAN SURFACE HIGH SLIDING THROUGH
THE OHIO VALLEY WITH COOLER NORTHERLY FLOW PREVAILING ACROSS THE
SOUTHERN/CENTRAL APPS.  AS THE SURFACE RIDGE SLIDES EAST ON
WEDNESDAY IT WILL EXTEND SOUTHWARD IN AN EARLY FALL CAD WEDGE
CONFIGURATION FURTHER REINFORCING THE COOLER/DRIER AIRMASS.
THUS...AS ENHANCED DEEP LAYER MOISTURE REMAINS TO THE SOUTH TIED TO
OLD FRONTAL BOUNDARY...SKIES SHOULD REMAIN MOSTLY SUNNY ON TUESDAY
AND WEDNESDAY.  THEREFORE THE FORECAST WILL REMAIN DRY THROUGH THE
MAJORITY OF THE PERIOD WITH THE HIGHLIGHTS BEING COOLER MORE FALL
LIKE TEMPERATURES ON TUESDAY...AND ESPECIALLY ON WEDNESDAY WHEN
DAYTIME HIGHS STRUGGLE TO REACH INTO THE MID 70S AND OVERNIGHT LOWS
DIP INTO THE 50S ACROSS NORTHEAST GA AND THE NC/SC PIEDMONT REGION.
AS FOR THE MOUNTAINS...MID TO UPPER 60S ARE FEATURED EACH AFTERNOON
WITH OVERNIGHT LOWS IN THE 40S.  ALTHOUGH WITH LOW CONFIDENCE...POPS
ARE SLOWLY REINTRODUCED WEDNESDAY AFTERNOON ALONG AND SOUTH OF THE
INTERSTATE 85 CORRIDOR AS WEAK UPGLIDE REGIME IS INDICATED BY
GUIDANCE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 2 PM SUNDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
THURSDAY WITH A VERY BROAD AND STEEP UPPER RIDGE SPREAD ACROSS MOST
OF THE CONUS. THE RIDGE IS EXPECTED TO REMAIN IN PLACE THRU
NEW DAY 7 OVER THE EASTERN HALF OF THE CONUS WHILE ANOTHER STEEP
UPPER TROF DIGS DOWN OVER THE ROCKIES BY THE END OF THE MEDIUM RANGE.

AT THE SFC...STRONG CANADIAN HIGH PRESSURE WILL BE CENTERED TO OUR
NORTHEAST AND OVER NEW ENGLAND WITH COOL AND DRY NELY LOW LVL FLOW
OVER THE FCST AREA. OVER THE NEXT FEW DAYS...THE LATEST LONG RANGE
GUIDANCE GRADUALLY MOVES THE HIGH A BIT WESTWARD BACK TOWARDS THE
GREAT LAKES. THIS DIFFERS FROM WHAT THE MODELS HAVE BEEN ADVERTISING
THE PAST COUPLE OF DAYS WITH THE HIGH DRIFTING SLOWLY EASTWARD OR
REMAINING NEARLY STATIONARY. THE ECMWF STILL REMAINS MORE BULLISH
WRT DEEPER LYR MOISTURE ENCROACHING UPON THE CWFA FROM THE SOUTH AND
EAST WHILE THE LATEST 12Z GFS KEEPS THE HIGHER RH VALUES JUST TO OUR
SOUTH THRU SAT. BY SUN...THE GFS DOES TRY TO SPIN UP SOME SORT OF
GULF OF MEX LOW WHICH SPREADS DEEPER MOISTURE OVER MOST OF THE CWFA
BY LATE SUN. THE ECMWF ALSO APPEARS TO SPIN UP SOMETHING IN THE
NORTHERN GOM BY THE END OF THE MEDIUM RANGE WITH DEEPER MOISTURE
SPREADING ACROSS THE SE REGION. WITH THAT SAID I BUMPED UP POPS JUST
A BIT ON THURS AND FRI...BUT KEPT MOST OF THE CWFA AT JUST SLIGHT
CHANCE OR BELOW. TEMPS WERE CHANGED VERY LITTLE WITH THE COOLEST
VALUES EXPECTED AT THE BEGINNING OF THE PERIOD ON THURS WITH SOME
MINOR WARMING GOING INTO THE WEEKEND...HOWEVER HIGHS SHOULD REMAIN
BELOW CLIMO THRU DAY 7.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AT KCLT...THE SFC COLD FRONT WILL BE KNOCKING ON THE DOOR AT 06Z.
BRIEF NRLY GUSTS WILL BE POSSIBLE POST FROPA THROUGH DAYBREAK...BUT
MIXING THROUGH THE DAY DOES NOT APPEAR ESPECIALLY DEEP TO SUPPORT
FREQUENT GUSTS. STEADY NE FLOW AT 10 KT OR LESS IS EXPECTED. MORNING
VFR CIGS WILL QUICKLY SCATTER...WITH MAINLY HIGH CLOUDS EXPECTED
LATE DAY WITH THE UPPER SHORTWAVE CLOSING OFF THROUGH THE EVENING
HOURS. THE TAF WILL BE FREE OF PRECIPITATION...WITH ANY EARLY
MORNING SHOWERS S OF THE AREA...AND PROFILES TOO DRY TO SUPPORT ANY
SHOWERS WITH THE STRONG SHORTWAVE THIS AFTN/EVENING.

ELSEWHERE...ANY PRE/FRONTAL SHOWERS APPEAR SAFELY SE OF KAND TO
KGSP...WITH THE REST OF THE FORECAST AREA DRY. VFR CIGS WILL
STEADILY SCATTER OUT WITH THE DRYING POST FRONTAL NRLY FLOW THROUGH
THE MID TO LATE MORNING HOURS. NW FLOW MOISTURE COULD ALLOW CIGS TO
BRIEFLY FLIRT WITH MVFR AT KAVL PRIOR TO DAYBREAK...BUT GENERALLY
VFR CIGS ARE EXPECTED THERE AS WELL. KAVL IS ALREADY SEEING SOME
COLD ADVECTION GUSTS...AND BRIEF NRLY FLOW GUSTS CANNOT BE RULED OUT
AT THE FOOTHILL SITES AS THE COOLER AND DRIER AIR SPILLS IN TODAY.
HOWEVER...MIXING LOOKS FAIRLY SHALLOW. ANY INTERACTION OF LINGERING
BOUNDARY LAYER MOISTURE AND UPPER SUPPORT WITH THE SHORTWAVE SHOULD
AFFECT MAINLY THE EXTREME SRN PIEDMONT THIS AFTN...WITH ANY ISOLD
SHRA POTENTIAL S OF KAND. EXPECT STEADY N TO NE FLOW AT 10 KT OR
LESS...EXCEPT NW WITH LOW END GUSTS AT KAVL...AND FEW TO SCT VFR
CLOUDS.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH THE
WEEK...WITH EASTERLY FLOW MOISTURE POSSIBLY RETURNING FROM THE COAST
THIS WEEKEND.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-05Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  88%     MED   79%     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...NONE.
SC...NONE.

&&

$$
SYNOPSIS...JPT
NEAR TERM...HG
SHORT TERM...CDG
LONG TERM...JPT
AVIATION...HG







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