Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 190654
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
254 AM EDT SAT APR 19 2014

.SYNOPSIS...
A MOIST LOW PRESSURE SYSTEM WILL MOVE SLOWLY ACROSS SOUTHERN GEORGIA
TODAY...AND CONTINUE TRACKING EAST OFF THE SOUTH CAROLINA COAST
TONIGHT THROUGH SUNDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN
MONDAY...BEFORE A COLD FRONT PUSHES ACROSS THE REGION ON TUESDAY. A
BROAD AND DRY AREA OF HIGH PRESSURE WILL THEN BUILD IN FROM THE
NORTH WEDNESDAY AND LINGER THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 150 AM EDT...SATELLITE IMAGERY SHOWED AN UPPER LEVEL CLOSED
LOW MOVING EWD ACROSS SW GA AND THE FL PANHANDLE VERY EARLY THIS
MORNING. IN ADDITION...WATER VAPOR IMAGERY IS SHOWING DRY SLOTTING
WRAPPING IN FROM THE SW WHICH WILL CURTAIL POPS AND QPF IN SW
SECTIONS THROUGH DAYBREAK. THE SFC LOW UNDER THE CLOSED UPPER SYSTEM
WILL MOVE EWD ALONG THE GA/FL BORDER TODAY AND THEN OFF THE COAST BY
THIS EVENING...WITH A CORRESPONDING GRADUAL DECREASE IN PRECIPITABLE
WATER VALUES IN AREA PROFILES FROM THE EARLY MORNING MAX VALUES.
ALTHOUGH UPPER LEVEL DIVERGENCE WILL GRADUALLY WEAKEN TODAY...DEEP
LAYER QG FORCING WILL CROSS THE FORECAST AREA BETWEEN 12Z AND 18Z
BEFORE DIMINISHING FROM THE W. IN ADDITION...AN AXIS OF STRONG
FRONTOGENESIS WILL CONTINUE THROUGH THE HEART OF THE FORECAST AREA
THIS MORNING BEFORE WEAKENING THIS AFTERNOON AND DIMINISHING TONIGHT
AS THE LOW PRESSURE SYSTEM MOVES AWAY OFFSHORE. THIS FRONTOGENESIS
MAX MAY PIVOT ACROSS PIEDMONT SECTIONS TO PRODUCE THE HEAVIEST
RAINFALL GOING FORWARD ACROSS THE CHARLOTTE METRO AREA. SERIOUS
CONSIDERATION HAS BEEN GIVEN TO A FLOOD WATCH ACROSS THE CLT METRO
AREA...BUT GIVEN THE WEAK RAINFALL RATES THUS FAR...AND THE FFG AND
HEADWATER GUIDANCE VALUES...IT APPEARS THAT ANY HYDRO PROBLEMS
SHOULD BE FAIRLY ISOLATED. WILL CONTINUE THE HWO MENTION FOR HEAVY
RAINFALL...BUT ADDRESS ANY HYDRO PROBLEMS AS THEY ARISE WITH SHORTER
FUSE PRODUCTS.

IN ADDITION TO THE RAINFALL...THE TIGHTENING PRES GRADIENT WILL
CAUSE NE WINDS TO PICK UP...WITH GUSTS WELL INTO THE 20S AND
POSSIBLY ABOVE 30 MPH AT TIMES THIS AFTN ACROSS THE PIEDMONT. SFC
CAD REMAINING IN PLACE THROUGH TONIGHT WILL KEEP THE DIURNAL TEMP
RANGE FAIRLY SMALL. PRECIPITATION SHOULD GRADUALLY END FROM THE WEST
TONIGHT AS THE MOISTURE AND FORCING DIMINISH.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 230 AM SATURDAY...THE STACKED LOW PRES SYSTEM WILL CONTINUE TO
SLOWLY DRIFT EAST AWAY FROM THE CAROLINA COASTS ON SUNDAY...WITH
WRAP-AROUND CLOUD COVER AND DECENT NELY LLVL FLOW LINGERING ATOP THE
CWFA. IT DOES LOOK LIKE POPS SHUD PRETTY MUCH BE OVER ACRS THE AREA
BY DAYBREAK SUNDAY...BUT A SLGT CHC DOES LINGER IN THE SE ZONES THRU
MIDDAY. WITH THE COOL NE FLOW AND LINGERING CLOUDS...I UNDERCUT MOS
TEMPS...ESP IN THE EAST.

SUNDAY NIGHT THRU MONDAY...SHORTWAVE RIDGING RIPPLES ACRS THE AREA
BEHIND THE DEPARTING LOW. TEMPS REBOUND TO NEAR NORMAL READINGS
UNDER MOSTLY CLEAR SKIES.

MONDAY NIGHT...THE NEXT SHORTWAVE TROF APPROACHES FROM THE WEST.
HEIGHT FALLS ALOFT AND LLVL MOISTURE ARRIVING WITHIN INCREASING WLY
FLOW MAY SUPPORT A FEW SHWRS ALONG THE NC/TN BORDER OVERNIGHT. BUT
OTHERWISE...JUST AN INCREASE IN CLOUDS AND TEMPS A COUPLE CATEGORIES
ABOVE NORMAL.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 245 AM SATURDAY...MODELS STILL IN GOOD AGREEMENT ON TIMING A
COLD FROPA ACRS THE CWFA ON TUESDAY. THE FRONT WILL BE RELATIVELY
WEAKLY FORCED. BUT THERE SHUD BE ENUF Q-VECTOR CONVERGENCE COUPLED
WITH LLVL FRONTAL CONVERGENCE AND MOISTURE TO SUPPORT AT LEAST
SCATTERED SHWRS WITH THE FRONT. THE TIMING LOOKS GOOD FOR ABOUT
MAXIMUM DAYTIME HEATING INSTBY...WITH THE GFS MOST BULLISH WITH UP
TO 1000 J/KG OF SBCAPE BY 18Z TUESDAY. HOWEVER...I THINK THE
DOWNSLOPE W/NW LLVL FLOW WILL LIMIT COVERAGE AND OVERALL INSTBY. THE
GFS HODOGRAPHS ALSO DON/T SHOW MUCH SHEAR FOR ORGANIZED
CONVECTION...WITH UNIDIRECTIONAL W/NW FLOW ONLY INCREASING TO ABOUT
30 KTS IN THE MID LVLS. TEMPS WILL BE ABOVE NORMAL...UPR 70S TO LWR
80S EAST OF THE MTNS...ASSUMING FRONT PUSHES THRU LATE AFTN/EVE.

TUESDAY NIGHT THRU END OF THE WEEK...UPR FLOW CONTINUES TO BE QUITE
PROGRESSIVE...WITH ANOTHER UPR RIDGE BUILDING IN FOR WEDNESDAY AND
THURSDAY...FOLLOWED BY ANOTHER LATITUDINAL TROF APPROACHING THE AREA
FRIDAY. TEMPS REMAIN NEAR OR SLIGHTLY ABOVE NORMAL...WITH THE SFC
HIGH PRES CENTER TRANSLATING EAST ACRS THE GREAT LAKES. A COLD FRONT
WILL PUSH INTO THE OHIO VALLEY FRIDAY...WITH SLGT CHC TO LOW-END CHC
POPS CREEPING BACK IN BY FRIDAY EVENING.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...IFR TO MVFR LEVEL CLOUDS HAVE FILLED IN AROUND THE KCLT
AIRFIELD...BUT GUIDANCE INSISTS ON KCLT REMAINING AN ISLAND OF
MAINLY MVFR TO VFR CIGS. STILL THINK THAT MOISTURE AND RAINFALL WILL
EVENTUALLY OVERCOME THE BOUNDARY LAYER TO PRODUCE AT LEAST TEMPO IFR
CONDITIONS AFTER 08Z. ANTICIPATE MAINLY MVFR CIGS THROUGH THE DAY
WITH PERIODS OF MODERATE RAINFALL AS THE FRONTOGENESIS MAX PIVOTS
OVERHEAD. ADDITIONAL TEMPO IFR CIGS WILL LIKELY BE NEEDED IN LATER
ISSUANCES. THE TIGHTENING PRES GRADIENT SHOULD EASILY PRODUCE GUSTS
INTO THE 20S THROUGH MOST OF THE TAF PERIOD.

AT KAVL AND KHKY...THE WESTERN NC TAF SITES WILL BE THE FARTHEST
FROM THE DEEPER MOISTURE WITH THE SE LOW...AND THE LEAST LIKELY TO
EXPERIENCE ANY EXTENDED PERIODS OF IFR CIGS. IFR CIGS ARE
POSSIBLE...BUT FOLLOWING A MOS CONSENSUS OF MAINLY MVFR TO LOWERING
VFR SEEMS REASONABLE. BRIEF N TO NE WIND GUSTS ARE LIKELY AS
WELL...BUT WITH LESS MAGNITUDE THAN TAF LOCATIONS FARTHER SE.

AT THE UPSTATE TAF SITES...IFR CIGS SHOULD CERTAINLY MAKE A RUN AT
THE AIRFIELDS THROUGHOUT THE MORNING HOURS IN LIGHT TO MODERATE
RAINFALL. THE MOST PRUDENT COURSE WILL BE TO TEMPO IFR CIGS IN AFTER
08Z...SOONER AT KGSP...AND THEN FEATURE MAINLY MVFR CIGS THROUGH THE
COURSE OF THE DAY. NE FLOW WILL STEADILY INCREASE AS THE PRES
GRADIENT TIGHTENS...AND GUSTS TO BETTER THAN 25 KT WILL BE LIKELY
TODAY THROUGH THIS EVENING. RAIN SHOULD TAPER OFF FROM THE WEST LATE
IN THE PERIOD.

OUTLOOK...CEILING RESTRICTIONS MAY WELL LINGER INTO SUNDAY MORNING
BEFORE MOISTURE PULLS AWAY WITH THE SLOWLY DEPARTING OFFSHORE LOW
PRESSURE SYSTEM. DRY HIGH PRES WILL THEN DEVELOP THROUGH
MONDAY...WITH A FAIRLY WET FRONTAL SYSTEM EXPECTED ON TUE.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-07Z
KCLT       HIGH  95%     HIGH  98%     HIGH  82%     HIGH  85%
KGSP       HIGH  83%     HIGH  96%     HIGH  90%     HIGH  80%
KAVL       HIGH  95%     HIGH  86%     MED   69%     HIGH  84%
KHKY       HIGH  96%     MED   78%     MED   66%     HIGH  97%
KGMU       MED   79%     HIGH  90%     HIGH  81%     HIGH  81%
KAND       HIGH  86%     HIGH  92%     HIGH  95%     HIGH  87%

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...ARK
NEAR TERM...HG
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG






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