Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 291848
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
248 PM EDT WED JUL 29 2015

.SYNOPSIS...
A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE NORTHWEST ON
THURSDAY AND SETTLE SOUTHEAST OF THE REGION ON FRIDAY. THE FRONT AND
ASSOCIATED DEEPER MOISTURE WILL LIKELY REMAIN CONFINED TOWARD THE
SOUTHEAST COASTLINE THROUGH THE WEEKEND...WITH SLIGHTLY COOLER
TEMPERATURES EXPECTED OVER THE FORECAST AREA. LOW LEVEL MOISTURE
WILL GRADUALLY RETURN EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
OF 225 PM...RADAR SHOWS SCT SHOWERS/THUNDERSTORMS ALIGNED ALONG
THE BLUE RIDGE AND ALSO OVER THE SOUTHERN UPSTATE ALONG AN AXIS OF
HIGHER CAPE. CELLS EXHIBITING ONLY SLOW MOVEMENT TO THE SE. WITH
PRECIP. WATER AROUND 2 INCHES...LOCALLY HEAVY RAIN/FLOODING IS THE
MAIN THREAT THIS AFTERNOON. CAMS INDICATE THAT SOME SCT CONVECTION
MAY LINGER INTO THE EVENING HOURS...BUT IT SHOULD DISSIPATE BY
MIDNIGHT.

IN REGARD TO THE BIG PICTURE FOR THE SHORT TERM. AN UPPER LOW
DEEPENING OVER THE HUDSON BAY WILL PROMOTE FALLING HEIGHTS ACROSS THE
EASTERN U.S. THIS WILL DRIVE A COLD FRONT SE WHICH WILL APPROACH THE
NC MOUNTAINS BY 12Z THURSDAY. THE FRONT WILL THEN PROCEED TO CROSS
THE WESTERN CAROLINAS AND NE GA ON THURSDAY.

IN REGARD TO THE SENSIBLE WEATHER...THE OVERNIGHT WILL FEATURE
PARTLY CLOUDY AND HUMID CONDITIONS WITH SOME LOCALLY DENSE VALLEY
FOG DEVELOPING IN THE MOUNTAINS AFTER MIDNIGHT...AND MAINLY JUST
LIGHT FOG OUTSIDE THE MOUNTAINS. SOME SHOWERS/STORMS ASSOCIATED WITH
THE APPROACHING COLD FRONT MAY REACH THE MOUNTAINS EARLY THURSDAY
MORNING...SO HAVE POPS INCREASING INTO THE CHANCE CATEGORY THERE.

FRONTAL CONVERGENCE COMBINED WITH THE FALLING HEIGHTS SHOULD LEAD TO
SCT TO NUMEROUS THUNDERSTORMS DEVELOPING ACROSS THE AREA DURING
THURSDAY WITH THE BEST COVERAGE DURING THE AFTERNOON OUTSIDE THE
MOUNTAINS. STRONG HEATING AND IMPROVING LAPSE RATES MAY SUPPORT A
FEW SEVERE STORMS THURSDAY AFTERNOON. SPC HAS MOST OF THE AREA
OUTSIDE THE MOUNTAINS IN A MARGINAL RISK FOR THURSDAY. TEMPERATURES
WILL REAMAIN ABOVE CLIMO WITH LOWS IN THE 60S MOUNTAINS TO LOW 70S
ELSEWHERE...AND HIGHS FROM THE MID 80S MOUNTAINS TO THE LOWER TO MID
90S ELSEWHERE.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM WEDNESDAY...THE BIG STORY FOR THE SHORT TERM PERIOD
WILL BE THE ESTABLISHMENT OF AN EASTERN LONG WAVE TROUGH...WITH THE
AXIS OF SAID TROUGH EXPECTED TO SET UP ALONG THE EAST COAST BY EARLY
IN THE PERIOD. THIS SHOULD ALLOW THE FRONTAL BOUNDARY...AND
ATTENDANT CONVECTION TO BE CARRIED SOUTHEAST OF THE FORECAST AREA
THURSDAY EVENING. WHILE THICKNESS VALUES WILL NOT CHANGE MUCH IN THE
WAKE OF THE BOUNDARY...ESSENTIALLY RESULTING IN NEAR-CLIMO TEMPS
THROUGH THE PERIOD...THE MAIN IMPACT WILL BE THE INTRODUCTION OF AN
UNSEASONABLY DRY AIR MASS. IN FACT...DEWPOINTS MAY MIX OUT WELL INTO
THE 50S FRI AFTERNOON. THE RESULT WILL BE VIRTUALLY NO POSITIVE
BUOYANCY... AS DEPICTED BY THE LATEST RUNS OF THE NAM AND THE GFS.
POPS WILL THEREFORE BE FEATURES WELL BELOW CLIMO...AND IN FACT BELOW
20 PERCENT ACROSS THE MAJORITY OF THE FORECAST AREA FRI AFTERNOON
AND EVENING. NOT MUCH CHANGE IN THE AIR MASS IS ANTICIPATED THROUGH
SATURDAY...AND POPS REMAIN AT 20 PERCENT OR LESS DURING THE
AFTERNOON AND EVENING. OVERALL...IT/S SHAPING OUT TO BE A DECENT
WEEKEND AS FAR AS EARLY AUGUST GOES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH BROAD UPPER TROFFING OVER THE EASTERN CONUS AND BROAD
UPPER RIDGING IN PLACE OVER THE WESTERN CONUS. THIS PATTERN IS
EXPECTED TO REMAIN IN PLACE THROUGH MOST OF THE PERIOD WITH SOME
DEAMPLIFICATION OF THE UPPER TROF EXPECTED BY THE END OF THE PERIOD
NEXT WEDNESDAY. AT THE SFC...HIGH PRESSURE CENTERED TO OUR NW WILL
BE OVER THE FCST AREA AT THE START OF THE PERIOD AND SHOULD LINGER
INTO EARLY NEXT WEEK...GRADUALLY GETTING WEAKER. THE ECMWF STILL
TRIES TO SPIN UP SOME SORT OF SFC LOW TO OUR SOUTH EARLY IN THE
PERIOD...YET THE GFS CONTINUES TO SUPRESS ANY LOW DEVELOPMENT.
TOWARDS THE VERY END OF THE PERIOD ON DAY 7...THE LONG RANGE
GUIDANCE SUGGESTS THAT ANOTHER CANADIAN SFC HIGH WILL BEGIN TO MOVE
INTO THE REGION FROM THE NW. AS FOR THE SENSIBLE FCST...WE CAN
EXPECT MOSTLY DIURNAL CHANCES FOR SCT CONVECTION EACH DAY/EVENING
WITH THE BEST CHANCES OVER THE SE ZONES. CHANCES INCREASE A BIT FOR
TUES AND WED OVER THE NW ZONES WITH BETTER LOW LVL CONVERGENCE
EXPECTED. TEMPS WILL START OUT RIGHT AROUND NORMAL AND REMAIN NEAR
NORMAL...IF NOT A FEW DEGREES ABOVE...THROUGH THE PERIOD.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...CONVECTIVE CONCERNS THIS AFTERNOON INTO THE EVENING ARE
THE MAIN CONCERN. SCT SHRA/TSRA DEVELOPING WEST/NORTH OF THE
AIRFIELD BUT MOVING ONLY VERY SLOWLY SE. CAMS INDICATE THAT CELLS
WILL CONTINUE TO DEVELOP VICINITY AIRFIELD SO WILL CONTINUE WITH
TEMPO TSRA 19Z-23Z. COULD SEE SOME LIGHT FOG AT AIRFIELD CIRCA
SUNRISE.

ELSEWHERE...OVERALL CONDITIONS SIMILAR TO CLT WITH SCT TSRA
DEVELOPING. EXPECT THAT ALL AIRFIELDS WILL HAVE STORMS IN VICINITY
SO WILL CARRY TEMPO TSRA THIS AFTERNOON. SOME MVFR FOG AND PATCHY
IFR CONDITIONS LATE TONIGHT.

OUTLOOK...AN UPPER LEVEL TROUGH WILL AMPLIFY ACROSS THE ATLANTIC
STATES LATE IN THE WEEK...WITH THE PASSAGE OF A SURFACE COLD FRONT
THURSDAY NIGHT. THE POTENTIAL FOR CONVECTION WILL INCREASE THURSDAY
AFTERNOON AND EVENING WITH THE FRONTAL PASSAGE. GENERALLY DRY AND
QUIET WEATHER IS EXPECTED FRIDAY THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  97%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH  94%     HIGH 100%
KAVL       HIGH  93%     HIGH 100%     LOW   55%     HIGH  91%
KHKY       HIGH  99%     HIGH 100%     HIGH  91%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH  94%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  94%     HIGH  97%

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...LG
SHORT TERM...JDL
LONG TERM...JPT
AVIATION...LG


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