Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 012052
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
452 PM EDT FRI AUG 1 2014

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL REMAIN WEDGED OVER THE CAROLINAS
THROUGH SATURDAY AS AN UPPER TROUGH REMAINS CENTERED TO OUR WEST. TO
THE EAST...A FRONT WILL REMAIN NEARLY STATIONARY ALONG THE COAST
ALLOWING DEEP ATLANTIC MOISTURE TO CONTINUE TO SPREAD OVER THE AREA.
CONDITIONS ARE EXPECTED TO RETURN TO MORE TYPICAL LATE SUMMER
CONDITIONS BY THE MIDDLE OF NEXT WEEK AS THE BERMUDA STRENGTHENS TO
OUR EAST.

&&

.NEAR TERM /THROUGH SATURDAY/...
430 PM UPDATE...SOLID STRATUS DECK REMAINS OVER THE ERN HALF OF THE
CWFA WHERE WARM UPGLIDE CONTINUES OVER THE WEDGE. A WEAK SHORTWAVE
IS ALSO SHOWN LIFTING UP ACRS THIS AREA...COMING OUT OF THE SYNOPTIC
SCALE TROUGH. THE WRN HALF OF THE AREA HAS LARGELY CLEARED NOW THAT
THE UPGLIDE HAS WEAKENED. I GENERALLY EXPECT THESE TRENDS TO
CONTINUE. HOWEVER THE CLEARER SKIES IN THE W HAS ALLOWED SFC
DESTABILIZATION...WITH SBCAPES APPROACHING 1000 J/KG PER SPC
MESOANALYSIS. POP-UP SHRA WITH MORE ISOLATED TSRA SHOULD FILL BACK
IN TO SOME EXTENT. GENERALLY REDUCED POPS TO CHANCE RANGE EAST WHERE
THE PATTERN WILL REMAIN FAVORABLE FOR SOME PRECIP GENERATION INTO
THIS EVENING.

AT 910 AM EDT...AN UPPER LOW REMAINED OVER EASTERN CANADA...WITH A
POSITIVELY TILTED UPPER TROUGH EXTENDING SW TO THE GULF COAST. A
SHORTWAVE WAS EXITING THE BASE OF THE TROUGH OVER THE CAROLINAS...
WHILE ANOTHER WAS DIVING INTO THE TROUGH OVER THE MID MS RIVER
VALLEY. PRECIPITATION ASSOCIATED WITH THE FIRST SHORTWAVE WAS MOVING
ACROSS THE INTERSTATE 77 CORRIDOR THIS MORNING...WITH ALMOST NO
ACTIVITY IN ITS WAKE OVER THE MOUNTAINS AND FOOTHILLS.

THE MODELS SHOW A WEAK AND NEARLY STATIONARY FRONT LINGERING NEAR
THE COAST TODAY...WITH ROBUST MOISTURE EXTENDING INLAND OVER THE
BOUNDARY AS FAR WEST AS THE PIEDMONT...AND LESSER MOISTURE WEST TO
THE MOUNTAINS. WITH HEATING THIS AFTERNOON...CONVECTIVE CHANCES ARE
EXPECTED TO INCREASE OVER THE AREA...BUT WILL NOT BE AS GREAT AS
BEFORE THE SHORTWAVE ARRIVED YESTERDAY AND OVERNIGHT. WITH THE AREA
STILL RECOVERING FROM EARLIER HEAVY RAINFALL...ISOLATED FLOODING
CANNOT BE RULED OUT...BUT THE FLOOD WATCH FOR THE WESTERN PORTION OF
THE WILL BE CANCELLED. TEMPERATURES WILL RUN BELOW NORMAL DUE TO
LINGERING CLOUD COVER.

A STATIONARY FRONT WILL REMAIN TO THE SE OF THE FA OVERNIGHT...
ROBBING MOISTURE INTO THE AREA AS DEEP CONVECTION FIRES ALONG THE
COAST. MINS WILL REMAIN A FEW DEGREES BELOW NORMAL...MID TO UPPER
60S NON/MTNS AND L60S MTN VALLEYS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 200 PM FRIDAY...A POSITIVELY-TILTED UPPER TROF WILL LINGER
OVER THE GREAT LAKES TO THE LWR MS VALLEY INTO EARLY NEXT WEEK. A
SERIES OF EMBEDDED SHORTWAVES WILL ROUND THE BASE OF THE TROF AND
LIFT NE ACRS THE CWFA SUNDAY AND MONDAY. HOWEVER...OVERALL FORCING
WILL REMAIN FAIRLY WEAK. AN UPPER JET STREAK WILL ALSO EXIST BETWEEN
THE TROF AND A LARGE SUBTROPICAL RIDGE ACRS THE NORTH ATLANTIC. THE
OP MODELS ALL PLACE THE BEST RIGHT ENTRANCE REGION OF THE JET STREAK
TO THE EAST OF THE CWFA ALONG THE CAROLINA COASTS. AT THE SFC...A
QUASI-STATIONARY FRONT/INVERTED TROF WILL LINGER PARALLEL TO THE
UPPER JET...EXTENDING FROM FL NE TO NEW ENGLAND. GUIDANCE DIFFERS ON
EXACT PLACEMENT AND SHARPNESS OF THE TROF AXIS...WITH THE NAM STRONG
OUTLIER...CLOSING OFF A SFC LOW EAST OF FL AND LIFTING IT NORTH
TOWARD SC. MEANWHILE...THE GFS IS THE WEAKEST...ALLOWING MORE
MOISTURE AND INSTBY TO BE TRANSPORTED NW FROM THE COAST TO THE BLUE
RIDGE. I LIKE THE ECMWF REPRESENTATION...WHICH IS IN BETWEEN. THE
RESULT IS FOR A SLIGHT WARMING TREND (BUT STILL SLIGHTLY BELOW
NORMAL) AND GENERALLY DIURNAL SHOTGUN CHC POPS BOTH SUNDAY AND
MONDAY. INSTBY AND SHEAR WILL BE MODEST...SO SEVERE THREAT SHUD BE
LOW. ALSO...CONVECTION ALONG/EAST OF SFC TROF AXIS SHUD LIMIT THE
ANOMALOUSLY HIGH PWATS FROM REACHING THE AREA FROM THE EAST. AND
WITH LACK OF LLVL TRIGGERING AND WEAK UPPER FORCING...I DON/T EXPECT
MUCH OF A HEAVY RAIN THREAT.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 215 PM FRIDAY...THE MEDIUM RANGE STARTS AT 00Z TUESDAY. THE
MODELS IN OKAY AGREEMENT ON THE UPPER FLOW FLATTENING OUT
SOMEWHAT...BUT A GENERAL EAST COAST TROFINESS WILL LINGER INTO LATE
NEXT WEEK. THE COASTAL INVERTED TROF/STATIONARY FRONT FINALLY WASHES
OUT AND IS REPLACED BY DRIER AIR WORKING IN FROM THE WEST. TUESDAY
AND WEDNESDAY LOOK TO HAVE ONLY ISOLD TO WIDELY SCATTERED DIURNALLY
DRIVEN CONVECTION. TEMPS RETURN TO AROUND NORMAL.

THURSDAY AND FRIDAY...MODELS ARE TRENDING DEEPER WITH ANOTHER TROF
DIGGING ACRS THE GREAT LAKES TO THE MID SOUTH. THIS USHERS IN A WEAK
BACKDOOR COLD FRONT...WHICH THEN STALLS ACRS THE REGION. POPS
INCREASE TO MID TO HIGH CHC...AND TEMPS TREND A CATEGORY OR TWO
COOLER.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
21Z KCLT UPDATE...STRATUS STARTING TO ERODE WELL W AND SW OF THE
FIELD ATTM WHERE WARM UPGLIDE OVER COOL SFC WEDGE HAS WEAKENED AS
WELL AS WITH DOWNWARD MOTION IN THE WAKE OF A WEAK SHORTWAVE.
HOWEVER THE UPGLIDE IS SHOWN TO CONTINUE INTO THIS EVENING OVER THE
NC PIEDMONT...AND THE BACK EDGE IS MOVING SO SLOWLY THAT I AM
DOUBTFUL IT WILL MAKE IT TO KCLT BEFORE DIURNAL HEATING ENDS. IF IT
DOES NOT BREAK UP THEN THE MVFR CIG SHOULD LAST UNTIL LOWER IFR DECK
FORMS LATE TONIGHT.

AT KCLT...PRECIPITATION IS DIMINISHING WITH THE PASSAGE OF AN UPPER
SYSTEM...BUT SOME AFTERNOON CONVECTION REMAINS POSSIBLE WITH LIMITED
HEATING. INSTABILITY...THOUGH LIMITED...WIL BE SLOW TO DIMINISH THIS
EVENING. GUIDANCE LOWERS THE CIG TO LIFR BY DAWN...AND THE VSBY TO
IFR. CONFIDENCE ON THE VSBY IS MORE LIMITED...SO LOW END MVFR WILL
BE CARRIED AT THIS TIME. IMPROVEMENT SHOULD BE MORE RAPID ON
SATURDAY MORNING THAN IT WAS THIS MORNING...WITH VFR VSBY AND MVFR
CIG BY LATE MORNING. LIGHT NE WINDS WILL PERSIST.

ELSEWHERE...PRECIPITATION CHANCES WILL INCREASE WITH HEATING THIS
AFTERNOON...BUT COVERAGE AND INTENSITY SHOULD BE MUCH LESS THAN
YESTERDAY...OR THIS MORNING. GUIDANCE BRINGS CIGS TO LIFR BY DAWN IN
NC...AND MVFR AT SC SITES. GUIDANCE ALSO SUPPORTED VERY LOW DAYBREAK
VSBY IN NC...BUT WITH CONFIDENCE LIMITED...IFR WILL BE CARRIED
THERE...WITH MVFR AT SC SITES. MORE RAPID IMPROVEMENT IS EXPECTED ON
SATURDAY MORNING WITH VFR BY LATE MORNING...EXCEPT FOR MVFR CIG AT
KHKY. LIGHT WINDS WILL FAVOR THE NE ON THE NORTH SIDE OF A COASTAL
FRONT.

OUTLOOK...UNSETTLED WEATHER WITH ENHANCED PRECIPITATION CHANCES
ALONG WITH MORNING FOG/STRATUS ARE EXPECTED THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-21Z
KCLT       HIGH  96%     MED   79%     MED   78%     HIGH  87%
KGSP       HIGH  81%     HIGH  82%     MED   76%     HIGH  90%
KAVL       HIGH  91%     MED   65%     MED   77%     HIGH 100%
KHKY       MED   75%     MED   65%     MED   71%     MED   75%
KGMU       HIGH  89%     HIGH  84%     MED   69%     HIGH  90%
KAND       HIGH  94%     HIGH  84%     HIGH  82%     HIGH  90%

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...JAT/WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JAT/WIMBERLEY





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