Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 040536
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
136 AM EDT TUE AUG 4 2015

.SYNOPSIS...
DRY HIGH PRESSURE WILL WEAKEN THROUGH TUESDAY AS A WEAK COLD
FRONT DROPS SOUTH TOWARD OUR REGION. LOW LEVEL MOISTURE WILL
GRADUALLY RETURN THROUGH THE WORK WEEK AS THIS COLD FRONT APPROACHES
FROM THE AREA FROM THE NORTHWEST.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 135 AM...FCST REMAINS ON TRACK WITH CONVECTIVE ACTIVITY WITH
THE UPSTREAM MCS DIMINISHING AS IT MOVES EAST. COULD SEE A LITTLE
MORE IN THE WAY OF CONVECTIVE DEBRIS EARLY...BUT MOSTLY CLEAR SKIES
WILL PREVAIL. TEMPS ARE SIGNIFICANTLY COOLER THAN EXPECTED ACROSS
THE HIGHER ELEVATIONS...SO HAVE LOWERED LOWS ACCORDINGLY.

1015 PM UPDATE...FCST APPEARS TO BE ON TRACK. PRACTICALLY ALL TRACES
OF DIURNAL CU HAVE DISSIPATED...SO I LOWERED SKY COVER TO MCLR
WORDING FOR THE WHOLE AREA OVER THE NEXT COUPLE HRS. WEAKENING BUT
STILL ORGANIZED MCS OVER ERN KY WILL ENCOUNTER INCREASINGLY MORE
STABLE AIR AS IT WORKS INTO SW VA. ITS TRAJECTORY AND FWD
PROPAGATING CORFIDI VECTORS SUGGEST IT WILL REMAIN N OF OUR CWFA IF
IT EVEN HOLDS TOGETHER LONG ENOUGH TO MOVE THAT FAR EAST. HOWEVER
SOME OF THE CIRRUS DEBRIS WILL BE SEEN OVER THE NRN TIER OF ZONES.
DEWPTS HAVE REBOUNDED AS EXPECTED...BUT GUIDANCE STILL KEEPS FOG ON
THE LIGHT SIDE ALG/SOUTH OF I-85.

AS OF 215 PM EDT...THE FORECAST AREA WILL REMAIN IN THE BASE OF A
BROAD TROUGH EXTENDING FROM ERN CANADA THROUGH THE SE UNITED STATES
TONIGHT THROUGH TUESDAY. THE LOW LEVEL CIRCULATION MOVING NE ALONG
THE SE COASTLINE EARLY IN THE PERIOD SHOULD PERMIT ALL ASSOCIATED
DEEPER MOISTURE TO REMAIN CONFINED TO THE COASTAL PLAIN OVERNIGHT.
ANOTHER SEABREEZE FRONT MAY WORK IN FROM THE SE TO FURTHER ELEVATE
DEWPOINTS AND KEEP MINS ON THE WARM SIDE OF CLIMO. PATCHY DAYBREAK
FOG IS EXPECTED THROUGHOUT.

A COLD FRONT WILL APPROACH THE NORTHERN TIER ON TUESDAY AND POSSIBLY
TRIGGER ISOLD TO SCATTERED CONVECTION ALONG THE NRN BLUE RIDGE
DURING THE AFTERNOON HOURS. WESTERLY STEERING FLOW WOULD THEN DRIVE
ANY CONVECTION EASTWARD OVER THE NC PIEDMONT THROUGH LATE DAY.
PROFILES ARE STILL ON THE DRY SIDE...BUT 850 TO 500 MB LAPSE RATES
SHOULD STEEPEN TO 6.5 DEG C OR BETTER AND THE APPROACHING BOUNDARY
WILL AID TRIGGERING. A MOS BLEND OF LOW END POPS FOR THE NRN HALF
SEEMS REASONABLE. MAX TEMPS MAY GAIN ANOTHER DEGREE OVER MONDAY
VALUES AHEAD OF THE BOUNDARY IN MOST AREAS TOMORROW AFTERNOON.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
AT 200 PM EDT MONDAY...A LARGE UPPER LOW NEAR HUDSON BAY IS FORECAST
TO MOVE SLOWLY EASTWARD ALLOWING FLOW OVER THE SE U.S. TO BECOME
MORE ZONAL IN NATURE. AN UPPER SHORT WAVE WILL APPROACH FROM THE
WEST BY LATE THURSDAY. IN REGARD TO SENSIBLE WEATHER...A WEAK COLD
FRONT IS FORECAST TO SETTLE SOUTH OF THE AREA TUESDAY NIGHT WITH
PERHAPS SOMOE WIDELY SCT CONVECTION LINGERING DURING THE EVENING.
HIGH PRESSURE NOSING SOUTHWARD SHOULD ALLOW SOMEWHAT DRYER AIR TO
FILTER INTO THE REGION TUE NIGHT INTO WED. THIS SHOULD ALLOW FOR A
PERIOD OF QUIET WEATHER THROUGH WED FOR MOST OF THE AREA. THE
EXCEPTION MAY THE UPPER SAVANNAH RIVER VALLEY AND SW NC MOUNTAINS
WHERE MODELS SHOW SOME CONVECTIVE RESPONSE LATE WED AS THE SFC FRONT
BEGINS TO RETURN AS A WARM FRONT. THE 12Z NAM DEPICTS THE WEAK FRONT
FRONT MOVING ACROSS THE WESTERN CAROLINAS WED NIGHT TRIGGERING
PERHAPS SOME SCT CONVECTION. ON THURSDAY...THE APPROACH OF THE UPPER
SHORT WAVE SHOULD TRIGGER NUMEROUS SHOWERS AND THUNDERSTORMS IN THE
MOUNTAINS...WITH SCT AFTERNOON CONVECTION ELSEWHERE. TEMPS WILL
REMAIN QUITE WARM AS 1000-850MB THICKNESS FIELD SHOWS LITTLE CHANGE
DESPITE THE WEAK FRONTAL PASSAGE. MAX TEMPS ON THU MAY BE A COUPLE
DEGREES LOWER DUE TO INCREASED CLOUDS AND CONVECTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AT 145 PM EDT MONDAY...STARTING AT 00Z FRIDAY...WITH NEARLY ZONAL
WEST TO EAST UPPER FLOW AND SHORTWAVES MOVING THROUGH THE MID LEVEL
FLOW TOPPING THE SW RIDGE GOING EAST.  TWO SIGNIFICANT SHORTWAVES
WILL BE CROSSING THE SOUTHERN APPALACHIANS THURSDAY NIGHT AND
FRIDAY. SOME AMPLIFICATION OF THE PATTERN WILL OCCUR FRIDAY AND
SATURDAY WITH THE AXIS OF THE UPPER EAST COAST TROUGH ROUGHLY ACROSS
THE CAROLINAS. UPPER RIDGE AT THAT TIME WILL BE CENTERED OVER WEST
TEXAS. FOR SUNDAY AND MONDAY...UPPER RIDGE BUILDS A BIT MORE EAST AS
UPPER TROUGH HOLDS ALONG THE EASTERN SEABOARD. ANOTHER SIGNIFICANT
SHORTWAVE PASSING THROUGH IN MID WEEK WILL DIG THR 500MB TROUGH OVER
CAROLINAS AND SUPPRESS RIDGE TO THE WEST.

AT THE SURFACE...THE SLOW MOVING WEAK COLD FRONT WILL DROP SOUTH
OVER OUR REGION WITH THE PASSAGE OF THE SHORTWAVE.  THIS FRONT WILL
GRADUALLY MOVE JUST SOUTH OF OUR AREA OVER THE WEEKEND WITH THE
FRONT BECOMING STATIONARY SUNDAY AND MONDAY OVER SOUTH GEORGIA AND
THE SOUTHERN TIP OF SC.

RAISED POPS A BIT FOR THURSDAY NIGHT AND FRIDAY WITH THE SHORTWAVES
AND FRONTAL PASSAGE. INSTABILITY WILL BE WEAK TO MODERATE SOUTH OF
THE FRONT AND BEST CHANCES OF ANY RAIN WILL BE SUPPRESSED SOUTH OF
THE FRONTAL BOUNDARY. TEMPERATURES WILL BE AROUND OR SLIGHTLY BELOW
NORMAL OVER THE WEEKEND.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...VFR MOST LIKELY WILL PREVAIL THRU THE PERIOD. ANOTHER SEA
BREEZE HAS MOVED NORTH ACROSS THE AREA BRINGING AN INCREASE IN LOW
LEVEL MOISTURE. DESPITE THE IMPROVED SFC MOISTURE THIS WILL BRING...
THE CHC OF RESTRICTIONS AT DAYBREAK APPEARS TOO LOW TO MENTION AT
THIS TIME IN LIGHT OF DRY PROFILES...THE MIXING THAT OCCURRED MON
AFTERNOON...AND STRATUS WELL SE NEAR THE COAST. WINDS WILL VEER INTO
THE SW QUADRANT AS LOW PRESSURE PROGRESSES THRU ERN CANADA. SOME
GUIDANCE BRINGS KCLT UNDER THE INFLUENCE OF ANOTHER LOW RIDING ALONG
THE CAROLINA COAST...BUT IT LOOKS TOO WEAK TO BRING THEM AROUND TO
NW. CONVECTIVE CHANCES ARE SLIGHTLY BETTER TUE AFTN...BUT CHC
REMAINS LOW ENOUGH THAT IT WAS OMITTED. NWLY GUSTS FROM UPSTREAM
OUTFLOW BOUNDARIES ARE MORE LIKELY THAN ACTUAL SHRA/TSRA.

ELSEWHERE...WITH GOOD MIXING OVER MOST OF THE AREA MON AFTN...THE
BOUNDARY LAYER LIKELY DRIED OUT ENOUGH TO PRECLUDE FOG AT ALL SITES.
SEA BREEZE AGAIN MOVED NORTH ACROSS THE AREA...BUT MODELS GENERALLY
DO NOT DEPICT IT BEING ACCOMPANIED BY LOW STRATUS. WINDS WILL BE
VERY LIGHT BUT MOST LIKELY S TO SW. THESE WILL VEER TO A MORE WLY
DIRECTION BY THE END OF THE DAY. KAVL THE EXCEPTION WITH NNW WIND
THRU THE PERIOD. A FRONTAL BOUNDARY SAGGING INTO NRN NC WILL ENHANCE
DIURNAL CONVECTION...WARRANTING A PROB30 MENTION AT KAVL. NC
PIEDMONT WILL SEE ISOLD SHRA/TSRA BUT THIS DOESN/T WARRANT A MENTION
AT KHKY.

OUTLOOK...GRADUALLY INCREASING PRECIPITATION/RESTRICTION CHANCES ARE
EXPECTED THROUGH THE WEEK AS MOISTURE RETURNS AND A FRONT STALLS IN
OUR VICINITY...WITH A DISTURBANCE THEN MOVING ALONG IT.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH  83%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH  83%     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...DEO
NEAR TERM...HG/RWH/WIMBERLEY
SHORT TERM...LG
LONG TERM...DEO
AVIATION...RWH


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