Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 032046
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
446 PM EDT MON AUG 3 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 TUESDAY/...
430 PM UPDATE...THE CU FIELD LOOKS TO BE WANING ACRS THE MTNS AND
ACRS THE AREA FOR THAT MATTER. BACKED OFF PRECIP CHANCES
OVERALL...KEEPING AN ISOLD MENTION ALONG THE SRN ESCARPMENT ONLY FOR
THE NEXT HR OR SO. DEWPOINTS HAVE MIXED OUT SHARPLY AT A FEW OBS
SITES SINCE THE LAST UPDATE...SO I REVISED T/TD FOR THE NEXT FEW
HRS. STILL EXPECTING SEA BREEZE BOUNDARY TO LIFT INTO THE PIEDMONT
SIMILAR TO LAST NIGHT...WITH GUIDANCE CONSENSUS ON THAT REACHING AT
LEAST THE AREAS ALONG OUR SERN BORDER.

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 /TUESDAY NIGHT 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 /21Z MONDAY THROUGH SATURDAY/...
AT KCLT...HIGH BASED CUMULUS WILL LINGER THRU MID EVENING...WITH
MOSTLY THIN HIGH CLOUDS AT NIGHT. NONE OF THE GUIDANCE HAS LOW
STRATUS MAKING A RUN TOWARD THE AIRFIELD EARLY TUESDAY MORNING...BUT
THIS WILL NEED TO BE MONITORED AS ANOTHER SEABREEZE ALONG WITH
REINFORCING BOUNDARY LAYER MOISTURE RETURNS THIS EVENING. MVFR FOG
SEEMS THE BEST CONSENSUS FOR DAYBREAK VISIBILITY. WILL KEEP THE TAF
DRY THROUGH 18Z TUE...BUT CONVECTION CHANCES LOOK BETTER TO THE NW
THROUGH TUE AFTERNOON WITH A FRONT APPROACHING. WINDS WILL REMAIN
LIGHT S TO SE THE FIRST HALF OF THE PERIOD...LIKELY TOGGLING WNW TO
NW TUE MORNING...BUT STILL LIGHT.

ELSEWHERE...WINDS WILL REMAIN LIGHT...GENERALLY SRLY ACROSS THE
FOOTHILLS AND NW AT KAVL. MORNING MVFR FOG IS LIKELY...ESPECIALLY AT
KAVL WHERE SOME STRATUS WILL ALSO BE HINTED AT. PRECIP CHANCES LOOK
BETTER ACROSS WRN NC ON TUESDAY...BUT PROBABLY AFTER 18Z. WINDS WILL
VEER THROUGHOUT AS A BOUNDARY APPROACHES FROM THE NORTH.

OUTLOOK...GRADUALLY INCREASING PRECIPITATION/RESTRICTION CHANCES ARE
EXPECTED THROUGH THE WEEK AS MOISTURE RETURNS ALONG A STALLING FRONT
THROUGH MID WEEK...AND AHEAD OF A LOW PRESSURE SYSTEM LATE WEEK.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  93%     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 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...DEO
NEAR TERM...HG/WIMBERLEY
SHORT TERM...LG
LONG TERM...DEO
AVIATION...HG/WIMBERLEY


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