Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 082316
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
716 PM EDT TUE JUL 8 2014

.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA FROM THE NORTHWEST AND SHOULD
CROSS THE REGION THROUGH WEDNESDAY NIGHT. THIS SHOULD YIELD
HEIGHTENED PRECIPITATION CHANCES UNTIL AFTER THE FRONT PASSES. WEAK
HIGH PRESSURE WILL RETURN THROUGH THE WEEKEND BEFORE ANOTHER COLD
FRONT APPROACHES THE AREA BY EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
2300 UTC UPDATE...POPS HAVE BEEND ADJSUTED BASED ON RADAR TRENDS...
SPREADING COVNECTION EAST ACROSS THE BLUE RIDGE. QPF HAS BEEN
ADJSUTED ACCORDINGLY.

AS OF 230 PM EDT...CONVECTION DEVELOPED ALONG THE ERN SLOPES OF THE
MTNS AND THE ADJACENT FOOTHILLS THIS AFTN ALONG A DIFFERENTIAL
HEATING LINE CREATED BY HIGHER DEBRIS CLOUDS TO THE WEST...AND ALSO
AHEAD OF A WEAK UPPER VORTICITY MAXIMUM CROSSING THE SRN HALF OF THE
FORECAST AREA THIS AFTN. SBCAPE VALUES REMAIN 2000 TO 2500 J/KG IN
THIS AREA...BUT THE ACTIVITY WILL HAVE TO FIGHT IT/S WAY EAST INTO A
LOWER SBCAPE REGION WITH LOWER 60S DEWPOINTS AND A SLIGHTLY MORE
CAPPED ENVIRONMENT. BETWEEN OUTFLOWS WITH THIS ONGOING ACTIVITY AND
THE PASSING UPPER WAVE THROUGH EARLY EVENING...WILL FOCUS POP
COVERAGE JUST EAST OF THE MTNS EARLY...BUT WITH COVERAGE THEN
TURNING BACK TO THE WESTERN MOUNTAINS LATER TONIGHT AS PRE/FRONTAL
CONVECTION ARRIVES FROM ERN TN AND STOUT WESTERLY FLOW TRIGGERS
UPSLOPE FORCING. IN FACT...850 MB WINDS WILL VEER AND STRENGTHEN TO
SOME UNSEASONABLY HIGH VALUES OF 30 TO 35 KT BY 06Z...BUT
INSTABILITY SHOULD WANE OVERNIGHT. THE MAIN CONCERN FOR ANY
OVERNIGHT SEVERE WX WOULD BE WITH THE ARRIVAL OF A DECAYING
PRE/FRONTAL LINE ACROSS THE WRN NC MTNS.

A BROAD AREA OF WEAK Q VECTOR CONVERGENCE WILL DEVELOP FROM THE WEST
THROUGH WED AHEAD OF THE AXIS OF THE BROAD ERN CONUS TROUGH. THIS
WILL ARRIVE COINCIDENT WITH THE DEEPEST FRONTAL ZONE MOISTURE...WITH
THE BOUNDARY LIKELY BISECTING THE FORECAST AREA BY WED AFTN AND THEN
SETTLING SLOWLY SOUTHEAST. BOTH TRIGGERING AND INSTABILITY SHOULD BE
SOMEWHAT LIMITED GIVEN THE WEAK NATURE OF THE FRONT...LACK OF
VIGOROUS WAVES IN THE TROUGH ALOFT...AND CLOUDS TO INHIBIT HEATING.
WILL ORIENT POPS WITH LIKELY MTNS/CHC EAST EARLY...TRANSITIONING TO
SHOTGUN HIGH CHC THROUGHOUT DURING THE AFTN. CLOUDS SHOULD BE
THINNEST IN SE SECTIONS TO SUPPORT AT LEAST LOWER 90S FOR
HIGHS...BUT EXPECT MAXES TO BE AT LEAST A CATEGORY COOLER ELSEWHERE.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM TUE...AN EASTERN U.S. TROUGH WILL PREVAIL THROUGH THE
SHORT TERM WITH A COUPLE WEAK IMPULSES RIPPLING THROUGH THE MEAN
W-NW FLOW ALOFT. AT THE SURFACE...MODELS ARE IN DECENT AGREEMENT
THAT A BOUNDARY WILL LIE ACROSS UPSTATE SC INTO NE GA AT THE ONSET
OF THE PERIOD. SOME ONGOING CONVECTION IS LIKELY TO PERSIST IN THE
VICINTY OF THE BOUNDARY WED EVENING...BUT EXPECT WITH FORCING
REMAINING WEAK THAT COVERAGE OF PRECIP WILL TEND TO DECREASE
DIURNALLY WED NIGHT. FOR THU...THE NAM HAS COME INTO AGREEMENT WITH
THE GLOBAL MODELS THAT THE SURFACE BOUNDARY WILL CONTINUE TO LIE
ACROSS THE UPSTATE INTO NE GA AS UPPER FLOW REMAINS PARALLEL TO THE
BOUNDARY. IN FACT...THE NAM SUGGESTS THAT A WEAK WAVE WILL DEVELOP
ALONG THE BOUNDARY INCREASING THE LIKELIHOOD OF SCATTERED TO EVEN
NUMEROUS SHOWERS/THUNDERSTORMS WITH THE BEST COVERAGE FROM THE
CHARLOTTE AREA...THROUGH THE UPSTATE INTO NE GA. AS THE WAVE EXITS
THE AREA...DRYER AIR IS FORECAST TO FILER INTO THE REGION FROM THE
N-NW THU NIGHT. HENCE...POPS THU NIGHT AND FRI WILL BE PAIRED BACK.
MODELS DO SHOW SOME LIGHT QPF RESPONSE ON FRI AFTERNOON MAINLY IN
UPSLOPE AREAS AS WINDS BEGIN TO VEER TO THE SE. MAX TEMPS ARE
EXPECTED TO BE A CATEGORY BELOW AVERAGE EACH DAY.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY...UPPER H5 HEIGHTS WILL FALL ACROSS THE
SOUTHEAST FRI NIGHT INTO SAT AS AN UPPER RIDGE OF HIGH AMPLIFIES
ACROSS THE WESTERN CONUS WHILE AN UPPER LOW PRESSURE TROUGH OVER
SOUTH CENTRAL CANADA DIGS INTO THE GREAT LAKES REGION. MODELS
SUGGEST THAT THIS UPPER LOW PRESSURE TROUGH APPEARS TO BE
UNSEASONABLY STRONG WITH ITS CENTER HEIGHTS FALLING TO AROUND 545DM.
OUR FORECAST AREA WILL BE UNDER RATHER STRONG W/WNWLY FLOW LOFT
THROUGH TUESDAY AS THE TROUGH SWINGS ACROSS THE EASTERN CONUS.

AT THE SURFACE...A FRONTAL BOUNDARY JUST TO OUR SOUTH FRI NIGHT IS
FORECAST TO LIFT NORTH OF THE AREA BY SAT AFTERNOON AS BERMUDA HIGH
STRAIGHTENS ACROSS THE SE. THE REGION WILL BE UNDER THE INFLUENCE OF
BERMUDA HIGH THROUGH SUN NIGHT BEFORE IT WEAKENS AND SHIFT EAST AS A
COLD FRONT APPROACHES THE REGION FROM THE NW BY MON. THIS FRONT IS
PROGGED TO CROSS THE REGION LATE MONDAY INTO TUESDAY AND OFF THE SE
COAST BY TUE NIGHT. AS FOR OUR SENSIBLE WEATHER...MODEL SOUNDINGS
SUGGEST THAT WE WILL SEE UNCAPPED ALOFT WITH SEASONABLY UNSTABLE
ENVIRONMENT DURING THE AFTERNOON HOURS. HENCE...POPS REMAIN NEAR
CLIMO FAVORING IN THE HIGHER TERRAIN GIVEN BETTER UPSLOPE W/WSWLY
FLOW. THE BEST CHANCE FOR CONVECTION WILL BE ON LATE MONDAY AS THE
FRONT PUSHES THROUGH THE REGION. TEMPERATURES SHOULD REMAIN A FEW
DEGREES BELOW NORMAL THROUGH THE PERIOD.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
AT KCLT...CONVECTION WELL WEST OF KCLT IS NOT EXPECTED TO SURVIVE
THIS EVENING. SW WINDS WILL PERSIST...BUT SHOULD BE WEAKER WITH
LOWER GUSTS OVERNIGHT. GUIDANCE DOES NOT SUPPORT DAYBREAK
RESTRICTIONS. WINDS WILL COME UP AGAIN ON WEDNESDAY...AND CONVECTIVE
COVERAGE IS EXPECTED TO BE GREATER IN ADVANCE OF AN APPROACHING COLD
FRONT.

ELSEWHERE...CONVECTION CROSSING THE NC MOUNTAINS MAY AFFECT KAVL AND
KHKY EARLY THIS EVENING...BUT HAS LESS OF A CHANCE SURVIVING INTO
SC. WINDS SHOULD BECOME LIGHTER WITH LOWER GUSTS OVERNIGHT...BUT
PICK UP AGAIN ON WEDNESDAY AS A COLD FRONT APPROACHES. GUIDANCE
FAVORS MVFR DAYBREAK RESTRICTIONS AT KAVL...BUT NOT ELSEWHERE.
CONVECTIVE COVERAGE WILL BE GREATER ON WEDNESDAY AHEAD OF THE FRONT.

OUTLOOK...SCATTERED MAINLY AFTN THUNDERSTORMS WILL CONTINUE BEHIND
THE WEAK DEPARTING FRONT LATE THIS WEEK INTO THE WEEKEND AS HIGH
PRESSURE SLOWLY SETTLES OVER THE AREA. ANY RESTRICTIONS WOULD BE
CONFINED TO DIURNAL TSTMS AND MORNING VALLEY FOG EACH DAY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-23Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  81%     HIGH  82%     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...STAARMANN
NEAR TERM...HG/JAT
SHORT TERM...LG
LONG TERM...JOH
AVIATION...JAT






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