Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 231107
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
707 AM EDT TUE SEP 23 2014

.SYNOPSIS...
COOL HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH MID WEEK.
MOISTURE AND RAIN CHANCES INCREASE INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 655 AM EDT...WATER VAPOR SATELLITE IMAGERY CONTINUES TO
FEATURE A CLOSED MID LEVEL CIRCULATION NEAR THE CENTRAL SAVANNAH
RIVER AREA AT DAYBREAK THIS MORNING. MOISTURE IS INDICATED WRAPPING
WRAPPING NORTH AND WEST OF THIS FEATURE...SPREADING CLOUDS BACK INTO
THE SRN APPALACHIANS...BUT WITH ISOLD SHOWERS OR LIGHT RAIN STILL
CONFINED TO THE LOWER PIEDMONT EAST OF INTERSTATE 77 WHERE MOISTURE
IS A BIT DEEPER. DEEP LAYER QG FORCING WILL BE BEST FROM KCLT S AND
E THROUGH THE MORNING HOURS...THEN GRADUALLY SLIP EWD THROUGH THE
DAY. THE CLOUDS SHOULD KEEP A LID ON AFTN MAX TEMPS...WITH VALUES
GENERALLY 5 TO 10 DEGREES BELOW CLIMO IN MOST AREAS.

THE H5 LOW CENTER WILL LIKELY REMAIN OVER THE CENTRAL CAROLINAS
THROUGH TONIGHT...HOWEVER...LOW PRES DEVELOPMENT AT LOWER LEVELS
STILL APPEARS FOCUSED MAINLY ON THE FORMATION OF A COASTAL TROUGH.
THAT IS WHERE THE BEST MOISTURE AND GREATEST BAROCLINICITY SHOULD
SET UP...ALLOWING POPS TO TAPER OFF IN WRN PIEDMONT AREAS TONIGHT.
MINS HAVE BEEN ADJUSTED UP A BIT GIVEN THE DEEPER LAYER EASTERLY
FLOW AROUND THE LOW AND ASSOCIATED ATLANTIC MOISTURE INTRUDING WEST
TOWARD THE BLUE RIDGE.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AT 230 AM EDT TUESDAY...ON WEDNESDAY MORNING A CLOSED UPPER LOW WILL
BE OVER SC...WITH WEAK RIDGING TO ITS NORTH OVER THE NE USA...AND A
WEEK TROUGH OVER THE NORTHERN PLAINS. THE UPPER LOW LIFT NORTH INTO
PA BY THURSDAY MORNING...WHILE THE TROUGH UPSTREAM DRIFTS EAST
TOWARD THE GREAT LAKES. ON THURSDAY NIGHT THE NAM BRINGS THE UPPER
LOW SE TO CHESAPEAKE BAY...AND HAS AN UPPER RIDGE FROM THE GREAT
LAKES TO THE GULF STATES...WHILE THE GFS UPPER LOW IS ABSORBED BY A
TROUGH OFF THE NEW ENGLAND COAST...AND HAS ITS UPPER RIDGE STILL
OVER THE NORTHERN PLAINS.

AT THE SURFACE...A STATIONARY FRONT WILL BE OFF THE CAROLINA AND GA
COASTS ON WEDNESDAY MORNING...WITH SOME AMOUNT OF LOW TO MID LEVEL
MOISTURE EXTENDING INLAND TO THE MOUNTAINS ON AN EAST NORTHEAST FLOW
OFF THE ATLANTIC. THIS SETUP WILL SUPPORT AT LEAST SMALL POPS IN
LIMITED UPSLOPE FLOW. AS A SURFACE WAVE MOVES UP THE COASTAL FRONT
LATE ON THURSDAY...LOW LEVEL FLOW BACKS TO THE NORTHEAST...REDUCING
THE UPSLOPE COMPONENT.

MAXIMUM TEMPERATURES WILL RUN BELOW NORMAL...WHILE MINIMUM
TEMPERATURES WARM TO NEAR NORMAL...AS CLOUD COVER LIMITS HEATING
AND COOLING.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AT 230 AM EDT TUESDAY...ON FRIDAY MORNING AND UPPER RIDGE WILL
EXTEND FROM THE SW USA TO THE NORTHERN PLAINS...WITH A WEAK UPPER
TROUGH DOWNSTREAM OVER THE EAST COAST...AND ANOTHER RIDGE FROM FL TO
BERMUDA. BY SATURDAY THE NORTHER RIDGE REACHES THE GREAT LAKES AND
THE EAST COAST TROUGH WEAKENS FURTHER. ON SUNDAY THE GFS AND ECMWF
DIVERGE...WITH THE GFS HAVING A WEAK UPPER RIDGE OVER THE EAST
COAST...AND THE ECMWF HAVING A WEAK UPPER LOW NEAR THE DELMARVA
PENINSULA. ON MONDAY THE GFS RIDGE IS GONE...THE ECMWF LOW HAS
FILLED AND THE REMAINING TROUGH HAS MOVED OFFSHORE...AND BOTH MODELS
HAVE AN UPPER LOW OVER THE MID MS RIVER VALLEY.

AT THE SURFACE...FRIDAY WILL SEE HIGH PRESSURE CENTERED OVER
SOUTHERN ONTARIO...AND EXTENDING FROM NEW ENGLAND AND THE GREAT
LAKES SOUTH TO THE GULF STATES. A STATIONARY FRONT OFF THE CAROLINA
AND GA COASTS WILL EXTEND TO THE NORTHERN GULF OF MEXICO. THE MODELS
DISAGREE ON THE WESTERN EXTENT OF MOISTURE ASSOCIATED WITH THE FRONT
AND POSSIBLE WAVES ALONG IT...WITH THE ECMWF BRINGING MOISTURE MUCH
FARTHER INLAND THAN THE GFS. POPS WOULD BE MORE LIKELY ALONG THE
INTERSTATE 77 CORRIDOR THAN OVER THE FOOTHILLS OR MOUNTAINS...BUT
EVEN THE GFS HAS A DRYING TREND OVER THE WEEKEND AS THE FRONT STARTS
TO MAKE A SLOW SOUTHEAST PUSH.

ON SUNDAY NIGHT AND MONDAY...A SURFACE WAVE ON THE WESTERN PORTION
OF THE FRONT IN THE CENTRAL GULF BEGINS MOVING NORTH INTO THE LOWER
MS RIVER VALLEY. MOIST ISENTROPIC UPGLIDE OVER THIS BOUNDARY WILL
SPREAD NORTH OVER THE UPPER SAVANNAH RIVER VALLEY BY LATE
MONDAY...SUPPORTING PRECIPIATION.

TEMPERATURES WILL EXHIBIT A SLIGHTLY REDUCED DIURNAL TREND DUE TO
CLOUD COVER.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
AT KCLT...MOISTURE WRAPPING NWD THROUGH CENTRAL SC AROUND THE H5
CUTOFF LOW OVER THE CENTRAL SAVANNAH RIVER AREA WILL SEND ISOLD TO
SCATTERED LIGHT RAIN SHOWERS TOWARD KCLT THROUGHOUT THE DAY.
COVERAGE SHOULD BE SPOTTY ENOUGH THAT VCSH CAN BE USED. VFR CIGS
WILL BE PERSISTENT THROUGH THE PERIOD...WITH SOME BKN TO OVC050
POSSIBLE AT TIMES AS THE SHOWERS GET CLOSER AND BETTER ATLANTIC
MOISTURE WRAPS WESTWARD FROM THE COAST. WINDS WILL REMAIN LOCKED IN
FROM THE NE...BUT LOW END GUST POTENTIAL WILL EXIST WITH SHALLOW
MIXING TODAY. SOME DRYING IS INDICATED IN PROFILES TONIGHT...BUT
WITH CONTINUED ALTOCUMULUS CIGS ALOFT AS THE CLOSED LOW SPINS OVER
THE REGION.

ELSEWHERE...PROFILES REMAIN DRIER ACROSS THE FOOTHILLS AND MTNS THAN
INDICATED AT KCLT...AND SHRA CHANCES ARE VERY MINIMAL. VFR CLOUDS
ARE EXPECTED TO INCREASE AROUND THE H5 CUTOFF LOW TODAY AND THEN
SLOWLY DECREASE AT THE SC SITES TONIGHT AS THE DEEPER MOISTURE PULLS
BACK EAST. MOST LOCATIONS WILL SEE AT LEAST A PERIOD OF LOWERING VFR
STRATOCUMULUS AT SOME POINT TODAY. EXPECT STEADY NE FLOW OF 10 KT OR
LESS AT THE FOOTHILL SITES...WITH PRIMARILY N TO NW WINDS AT KAVL.

OUTLOOK...HIGH PRESSURE BUILDING N OF THE REGION SHOULD KEEP
CONDITIONS MOSTLY VFR...BUT EASTERLY FLOW ATLANTIC MOISTURE COULD
ENCROACH ON THE REGION AT TIMES WED THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-11Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   78%     HIGH 100%     HIGH 100%     HIGH  88%
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...JAT
NEAR TERM...HG
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...HG





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