Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 252329
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
729 PM EDT MON AUG 25 2014

.SYNOPSIS...
DRY AND COOLER CONDITIONS WILL CONTINUE THROUGH MID WEEK AS A RIDGE
OF HIGH PRESSURE PERSISTS ACROSS THE REGION. LATE THIS WEEK...
MOISTURE AND TEMPERATURES WILL GRADUALLY INCREASE ACROSS THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA AS A BERMUDA HIGH REDEVELOPS.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 720 PM EDT MONDAY...SETTING UP TO BE A RATHER NICE EVENING
ACROSS THE REGION WITH TEMPERATURES STARTING TO COOL INTO THE UPPER
70S.  SKIES HAVE CLEARED OUT FOR THE MOST PART WITH SOME LINGERING
LOW LEVEL CU ACROSS PORTIONS OF THE PIEDMONT REGION AND ALSO THE
SOUTHWEST NC MOUNTAINS.  GUIDANCE STILL INDICATES THIS WINDOW OF
CLEAR SKIES WILL BE SOMEWHAT BRIEF AS A PATCHY AREA OF LOW LEVEL
STRATUS WILL ADVECT IN FROM THE EAST BY MID MORNING AND LIKELY
LINGER INTO THE LATE MORNING HOURS.  AS FOR THE FORECAST...NO
SIGNIFICANT CHANGES NEEDED/MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AT 200 PM EDT MONDAY...AN UPPER RIDGE EXTENDING FROM NEW ENGLAND TO
NORTHERN MEXICO WILL BECOME MORE WEST TO EAST ORIENTED BY LATE
TUESDAY AS THE NORTHERN PORTION BREAKS DOWN AND ZONAL FLOW SETS UP
ACROSS CANADA AND THE NORTHERN TIER OF THE USA. MEANWHILE...AN UPPER
TROUGH WILL REMAIN OVER THE WESTERN ATLANTIC.

DRY HIGH PRESSURE WILL REMAIN ALONG THE EASTERN SEABOARD. MODEL TIME
HEIGHTS SHOW LINGERING MOISTURE AROUND 850 MB...THAT MAXIMIZES
AROUND DAYBREAK ON TUESDAY...AT WHICH TIME THE MODELS APPEAR TO
BRING SOME CLUSTERS OF CLOUD COVER SW OVER THE COASTAL PLAIN AND
PERHAPS THE EASTERN PIEDMONT. MINIMUM TEMPERATURES TONIGHT WILL RUN
AROUND FIVE DEGREE BELOW NORMAL IN COOL NE FLOW. MAXIMUM
TEMPERATURES TUESDAY WILL RUN AROUND FOUR DEGREES...MODERATING
UPWARD AS HEIGHTS RISE ALOFT WITH THE REORIENTATION OF THE UPPER
RIDGE.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 2 PM MONDAY...THE SHORT TERM FCST PICKS UP AT 00Z ON WEDNESDAY
WITH BROAD UPPER RIDGING IN PLACE OVER MOST OF THE CONUS. OVER THE
NEXT COUPLE OF DAYS...THE RIDGE WILL DEAMPLIFY AND FLATTEN
OUT...HOWEVER ANY NORTHERN STREAM ENERGY ASSOCIATED WITH THE POLAR
JET STREAM WILL REMAIN WELL TO OUR NORTH.

ON WEDNESDAY...UNSEASONABLY DRY HIGH PRESSURE WILL BE IN PLACE OVER
THE REGION WITH TS CRISTOBAL WELL OFF THE CAROLINA COAST. CRISTOBAL
SHOULD REMAIN WELL OFFSHORE AND IS NOT EXPECTED TO IMPACT OUR
SENSIBLE WEATHER. OTHERWISE...CONDITIONS WILL BE MOSTLY CLEAR AND
DRY WITH TEMPS REBOUNDING BACK TO NEAR NORMAL VALUES FOR LATE
AUGUST.

ON THURSDAY...ANOTHER REINFORCING HIGH WILL SLIDE EASTWARD ACROSS
THE GREAT LAKES AND HELP PUSH CRISTOBAL FARTHER NE. A WEAK COLD
FRONT WILL MOVE OVER THE CWFA LATE WED/EARLY THURS...ACTUALLY
BRINGING MORE MOIST AIR INTO THE REGION. THIS SHOULD INCREASE CLOUD
COVER...ESPECIALLY OVER THE NORTHERN ZONES...BY MIDDAY OR SO. I
BUMPED UP POPS TO A DIURNAL SLIGHT CHANCE FOR THE MTS AND PORTIONS
OF THE NC FOOTHILLS AND SOUTHERN PIEDMONT. THE LATEST NAM SOUNDINGS
ARE SHOWING SOME DECENT SFC BASED CAPE OVER THE MTS THURS
AFTERNOON/EVENING...HOWEVER THE MODEL HAS NOT BEEN VERY CONSISTENT
WITH CAPE PROFILES OVER THE PAST FEW RUNS. AS FOR TEMPS...HIGHS WILL
LIKELY BE ABOUT THE SAME AS WED IF NOT A BIT WARMER AND LOWS SHOULD
BE NEARLY A CATEGORY WARMER THAN EARLY WED.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 140 PM MONDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
FRIDAY WITH THE RELATIVELY FLAT UPPER RIDGE STILL IN PLACE OVER THE
SE CONUS AND A DEEP UPPER SHORTWAVE DIGGING DOWN OVER THE CENTRAL
AND SOUTHERN ROCKIES. OVER THE NEXT COUPLE OF DAYS...THE RIDGE WILL
REMAIN FLAT OVER OUR REGION AS THE UPPER SW MAKES ITS WAY TOWARDS
OUR WESTERN FRINGE. BY EARLY SUN...THE LONG RANGE MODELS HAVE THE SW
JUST TO OUR NW AND BY EARLY MON...THE FEATURE HAS PASSED TO OUR NE.

AT THE SFC...THE GREAT LAKES HIGH WILL SLIDE EASTWARD AND EVENTUALLY
MERGE WITH THE LARGER BERMUDA HIGH AS IT MOVES OFFSHORE. THIS WILL
GRADUALLY PUT THE REGION BACK INTO A MORE TYPICAL SUMMERTIME FLOW
PATTERN. BY SAT...SLY FLOW COUPLED WITH A RETURN OF DEEPER LYR
MOISTURE WILL RAMP UP CHANCES FOR WIDESPREAD SHOWERS AND TS. THE LATEST
RUN OF THE GFS DEVELOPS A LOW OVER THE SOUTHERN GREAT LAKES ON SAT
AND MOVES ITS ASSOCIATED FRONTAL BNDY TO OUR DOORSTEP BY EARLY MON.
IF THIS PANS OUT...WE COULD EXPECT DRIER AND COOLER AIR OVER THE
CWFA BY THE VERY END OF THE PERIOD. THIS SCENARIO...HOWEVER...IS NOT
CURRENTLY CONSISTENT WITH THE ECMWF SOLUTION...WHICH KEEPS THE FCST
AREA UNDER MOIST SLY FLOW THRU NEW DAY 7 AND DOES NOT DEVELOP THE
GREAT LAKES LOW UNTIL EARLY NEXT WEEK. AS FOR TEMPS...THE REGION
WILL REMAIN A BIT ABOVE NORMAL FOR LATE AUGUST AND LIKELY COOL A FEW
DEGREES BY DAY 7.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE
PERIOD AS HIGH PRESSURE AND NORTHEASTERLY FLOW DOMINATES.  MODELS
CONTINUE TO HINT AT LOW LEVEL MOISTURE PLUME ADVECTING ACROSS THE
PIEDMONT AND INTO THE FOOTHILLS BY EARLY/MID MORNING LEADING TO
REDEVELOPMENT OF A FEW LOW LEVEL STRATUS CLOUDS.  NOT EXPECTING
MOISTURE TO BE SUBSTANTIAL ENOUGH FOR CIGS TO DEVELOP THEREFORE
OPTED FOR SCT MENTION AT KCLT AND KHKY WITH ONLY FEW ELSEWHERE.
NORTHEAST WINDS WILL INCREASE ON TUESDAY MORNING TO AROUND 10-12KTS
WITH AN OCCASIONAL GUST POSSIBLE.  NOT EXPECTING PROLONGED GUSTING
AS THE PRESSURE GRADIENT RELAXES AND MIXED LAYER FLOW IS RATHER
UNIMPRESSIVE.  SKIES WILL REMAIN MOSTLY SUNNY ON TUESDAY WITH
OCCASIONAL HIGH LEVEL CIRRUS STREAMING THROUGH.

OUTLOOK...DRY HIGH PRESSURE WILL REMAIN OVER THE TERMINAL FORECAST
AREA THROUGH WED. THE AIRMASS WILL MODIFY MID TO LATE WEEK TO
GRADUALLY SUPPORT RETURNING ISOLD TO SCT DIURNAL THUNDERSTORMS...
ESPECIALLY ACROSS THE MTNS. MORNING LOW CLOUDS AND FOG WILL BE
POSSIBLE...ESPECIALLY IN THE MTN VALLEYS.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-23Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     MED   73%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   73%
KAVL       LOW   55%     LOW   52%     MED   63%     MED   60%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   73%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   73%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   73%

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...JOH
NEAR TERM...CDG/JAT
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...CDG






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