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Area Forecast Discussion

271
FXUS62 KGSP 200904
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
504 AM EDT SUN APR 20 2014

.SYNOPSIS...
WEAK HIGH PRESSURE BUILDS IN TODAY THROUGH MONDAY BEHIND...AS LOW
PRESSURE DRIFTS EAST OF THE AREA. A COLD FRONT WILL CROSS THE REGION
ON TUESDAY...FOLLOWED BY DRY HIGH PRESSURE FOR WEDNESDAY AND
THURSDAY. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION ON
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 445 AM EDT...REGIONAL RADARS SHOW THAT NEARLY ALL THE
LINGERING DEFORMATION ZONE LIGHT RAIN HAS DISSIPATED SOUTHEAST OF
CHARLOTTE...SO POPS HAVE BEEN CURTAILED ON THE LATEST UPDATE.
OTHERWISE...WATER VAPOR IMAGERY SHOWS THE SWIRLING UPPER LOW MOVING
OVER THE OFFSHORE WATERS EAST OF SAVANNAH THIS MORNING. AS THIS
UPPER VORTEX MOVES FARTHER OFFSHORE TODAY...RIDGING WILL BUILD IN
FROM THE WEST. GRADUAL SCATTERING OF THE CLOUDS WILL ALLOW TEMPS TO
REBOUND DESPITE THE LINGERING SFC HIGH PRES RIDGE REMAINING IN
PLACE. THE NAM HAS MORE EASTERLY FLOW MOISTURE AT 850 MB
TONIGHT...BUT THE PREFERRED GFS/ECM CAMP KEEP THE MOISTURE CONFINED
MORE TO THE COASTAL PLAIN. EXPECT MAXES IN THE 60S THIS AFTN AND
MINS IN THE 40S TONIGHT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM EDT SUNDAY...THE SHALLOW UPPER RIDGE WILL MOVE MORE
SQUARELY OVER THE REGION ON MONDAY...WHILE SFC HIGH PRESSURE SLOWLY
WEAKENS. ANTICIPATE MAXES TO REBOUND TO NEAR OR SLIGHTLY ABOVE
CLIMO. THE NEXT UPSTREAM TROUGH AXIS EJECTING EASTWARD FROM THE
PLAINS WILL APPROACH THE APPALACHIANS MON NIGHT AND CROSS THE
FORECAST AREA ON TUE ALONG WITH AN ATTENDANT COLD FRONT. INSTABILITY
WILL BUBBLE UP IN PIEDMONT SECTIONS TO SUPPORT PRE/FRONTAL AFTN TSRA
TUE...BUT SHEAR PROFILES APPEAR TOO WEAK FOR MUCH OF A SEVERE
THREAT. SHOWER CHANCES WILL END QUICKLY TUE EVENING...WITH MIN TEMPS
FALLING INTO THE UPPER 30S AT SOME HIGHER RIDGE TOPS EARLY WED
MORNING. HOWEVER...NO FROST OR FREEZE IS EXPECTED.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 300 AM SUNDAY...A SHARP UPR RIDGE AXIS WILL CROSS THE AREA
THURSDAY....FOLLOWED BY ANOTHER POTENT SHORTWAVE TROF...WHICH WILL
LIFT NE INTO THE GREAT LAKES ON FRIDAY. AT THE SFC...DRY HIGH PRES
BUILDS IN FROM THE NORTH WEDNESDAY AND THURSDAY...GRADUALLY SHIFTING
SOUTHEAST OF THE AREA TO ALLOW AN INCREASING RETURN FLOW ATOP THE
CWFA BY FRIDAY. LOW PRES DEEPENS OVER THE WESTERN GREAT LAKES
THURSDAY INTO FRIDAY...WITH A TRAILING COLD FRONT PUSHING ACRS THE
OH/TN VLYS. MODELS ARE IN GOOD AGREEMENT ON THE FRONT PUSHING THRU
THE CWFA ON FRIDAY WITH A LITTLE MORE INSTBY/SHEAR AND FORCING TO
WORK WITH COMPARED TO THE FRONT THAT IS EXPECTED TO CROSS ON
TUESDAY. STILL...IT DOES LOOK LIKE MOISTURE WILL STILL BE SOMEWHAT
LIMITED...AND THAT FAR OUT IN THE EXTENDED...THE SEVERE WX THREAT IS
STILL UNCERTAIN. THE FRONT SHUD PUSH THRU THE AREA BY EARLY
SATURDAY...WITH DRY WX. TEMPS LOOK TO BE A CATEGORY OR TWO COOLER
THAN TUESDAY FOR BOTH WEDNESDAY AND THURSDAY...WHICH IS NEAR NORMAL.
THEN TEMPS WARM BACK ABOVE NORMAL FOR FRIDAY AND SATURDAY.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
AT KCLT...ANY NEARBY LIGHT RAIN IN THE LINGERING DEFORMATION ZONE
HAS LARGELY DISSIPATED AT THIS POINT. LOW LEVEL DRY AIR ADVECTING IN
ON NE FLOW IS KEEPING CIGS AND VSBY VFR AND EXPECT THIS TO CONTINUE
THROUGH THE MORNING HOURS. OCCASIONAL GUSTS ARE LIKELY IN THE NE
FLOW...BUT WITH BETTER GUSTS DEVELOPING THROUGH THE DAY WITH MIXING.
WILL ALLOW VFR CIGS TO SCATTER OUT BY 15Z AND THEN LEAN TOWARD LESS
CLOUDS AS INDICATED ON THE GFS/ECM THROUGH THE EVENING HOURS.

ELSEWHERE...SLIGHTLY DRIER AIR ADVECTING IN ON NE FLOW IS KEEPING
VSBY AND CIGS AT VFR LEVELS AND THIS SHOULD PERSIST THROUGH THE
MORNING. KAVL WILL BE SHELTERED TO THE DRIER NE FLOW...AND KAND WILL
SEE SLIGHTLY LESS BOUNDARY LAYER DRYING...SO THESE LOCATIONS COULD
EXPERIENCE VERY BRIEF MVFR CONDITIONS TOWARD DAYBREAK.
HOWEVER...CONFIDENCE IS TOO LOW TO ADVERTISE THIS. EXPECT OCCASIONAL
GUSTS ON NE FLOW AT THE UPSTATE TAF SITES TODAY...ESPECIALLY PICKING
UP WITH MIXING BY LATE MORNING.

OUTLOOK...DRY HIGH PRES WILL DEVELOP THROUGH MONDAY. A FAIRLY WET
FRONTAL SYSTEM...WITH PIEDMONT THUNDERSTORMS...IS EXPECTED ON
TUE...WITH DRYING RETURNING MID WEEK.

CONFIDENCE TABLE...

            09-15Z        15-21Z        21-03Z        03-09Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     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...ARK
NEAR TERM...HG
SHORT TERM...HG
LONG TERM...ARK
AVIATION...HG






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