Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 280539
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
139 AM EDT THU AUG 28 2014

.SYNOPSIS...
A COLD FRONT WILL DROP DOWN INTO NORTH CAROLINA FROM THE NORTH
TOMORROW...LINGERING OVER THE REGION BRIEFLY BEFORE MOVING BACK
NORTH ON FRIDAY. MOISTURE AND TEMPERATURES WILL GRADUALLY INCREASE
THIS WEEKEND AS HIGH PRESSURE STRENGTHENS OVER THE SOUTHEAST...WITH
SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS EACH DAY.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 135 AM...CLEAR AND CALM CONDITIONS SHOULD FAVOR THE
DEVELOPMENT OF RADIATIONAL FOG WITHIN THE MTN VALLEYS. BASED ON
PERSISTENCE...I WILL CRAFT THE FORECAST TO INDICATE FOG BETWEEN
9Z-13Z. OTHERWISE...THE CURRENT FOG APPEARS IN GOOD SHAPE.

EVENING UPDATE...SFC HIGH PRESSURE WILL REMAIN SUPPORTED OVERNIGHT
AS AN ULVL RIDGE AXIS REMAIN ACROSS THE MIDWEST. SFC WIND SPEEDS ARE
CALM ACROSS THE CWFA AND WITH A DECOUPLING DRY ATMOS...STRONG SFC
INVERSIONS WILL KEEP WINDS NIL THROUGH DAYBREAK. DEWPOINT
DEPRESSIONS ACROSS THE MTN VALLEYS WILL LIKELY LOWER ENUF FOR
MORNING FG FORMATION...HOWEVER...LIMITED SFC MOISTURE WILL OFFSET A
WIDELY DENSE FG THREAT. AN APPROACHING BACK DOOR COLD FRONT WILL
INCREASE MOISTURE LEVELS ACROSS THE FAR NRN ZONES WITH SOME STCU
DEVELOPING NORTH OF THE I40 CORRIDOR.

730 PM EDT UPDATE...NO MAJOR CHANGES NEEDED TO THE GOING FCST.
HOURLY TEMPS RUNNING A LITTLE WARMER THAN THE FCST CURVE MOST
LOCALES AND WERE ADJUSTED.

AS OF 200 PM...THE REMAINDER OF THE AFTERNOON WILL REMAIN QUIET WITH
SUNNY CONDITIONS AND WARM TEMPS.

FOR THE OVERNIGHT...GENERALLY CLEAR CONDITIONS WILL PREVAIL THANKS
TO WEAK SFC HIGH PRESSURE AND AN USUALLY DRY AIRMASS FOR THIS TIME
OF YEAR. THE CLEAR AND CALM CONDITIONS SHOULD AGAIN PROMOTE VALLEY
FOG FORMATION THROUGHOUT THE MOUNTAIN VALLEYS. IN THE WAKE OF
CRYSTOBAL MOVING NORTHEAST OFF THE COAST AND SHORT WAVE ENERGY
MOVING THROUGH NEW ENGLAND...A BACKDOOR COLD FRONT WILL MAKE A RUN
AT THE AREA BY LATE TONIGHT. AN E-W NAM CROSS SECTION ACROSS THE
FORECAST AREA SHOWS INCREASING MOISTURE OVER EASTERN SECTIONS LATE
TONIGHT IN THE  850-700MB LAYER WHICH COULD SUPPORT SOME PATCHY MID
CLOUDS BY SUNRISE THU IN THE EAST.

ON THU...THE 12Z NAM AND GFS ARE IN GOOD AGREEMENT THAT THE BACKDOOR
FRONT WILL SETTLE SOUTHWARD INTO THE NORTHERN NC MOUNTAINS...EASTWARD
THROUGH THE I-40 CORRIDOR. MOISTURE ALONG THE BOUNDARY WILL INCREASE
THROUGHOUT THE DAY PROMOTING CAPES EXCEEDING 1000J/KG. THE MODELS
SHOW SOME CONVECTIVE RESPONSE DURING THE AFTERNOON HOURS MAINLY OVER
THE NC MOUNTAINS...BUT ALSO EASTWARD IN THE VICINITY OF THE
BOUNDARY. WITH A WEAK STEERING FLOW...DO NOT THINK THAT CONVECTIVE
COVERAGE WILL BE MORE THAN SCT. HENCE...WILL CONTINUE THE IDEA OF
SCT/WDLY SCT POPS OVER FROM THE MOUNTAINS EAST ALONG AND NORTH OF
I-40.

MIN TEMPS SHOULD BE ABOUT A CATEGORY HIGHER TONIGHT AS TEMPS WARMING
THIS AFTERNOON TO LEVELS ABOVE YESTERDAY. THU WILL BE A VERY WARM
DAY WITH MAX TEMPS A COUPLE DEGREES ABOVE CLIMO.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AT 200 PM EDT WEDNESDAY...ON THURSDAY EVENING AN UPPER RIDGE WILL BE
CENTERED NEAR THE SC AND GA...EXTENDING OVER MUCH OF THE SOUTHEAST.
THE RIDGE WILL MAINTAIN ITS HOLD ON GA AND THE CAROLINAS THROUGH
SATURDAY...WHILE IT WEAKENS TO THE WEST AS BROAD UPPER TROUGHING
SETS UP OVER THE CENTRAL ANS WESTERN PORTION OF THE NATION.

A STATIONARY FRONT WILL BE OVER NC ON THURSDAY EVENING...SERVING AS
A FOCUSING MECHANISM FOR PRECIPIATION...MAINLY TO THE NORTH OF THE
BOUNDARY WHERE ISENTROPIC UPGLIDE WILL EXIST. THE FRONT MOVES NORTH
AND AWAY FROM OUR AREA ON FRIDAY. MEANWHILE...THE GULF OF MEXICO
OPENS UP AND MOISTURE INVADED THE GULF STATE.  BY SATURDAY MORNING
GULF MOISTURE REACHES THE SOUTHERN APPALACHIANS...NEARLY
OVERSPREADING THE FOOTHILLS AND PIEDMONT OF THE WESTERN CAROLINAS
AND NE GA BY LATE SATURDAY. INSTABILITY WILL RETURN TO OUR AREA BY
SATURDAY AFTERNOON...BUT IS SOMEWHAT LIMITED...AS IS SHEAR. UPSLOPE
FLOW INTO MOUNTAIN TERRAIN WILL REMAIN RATHER LIMITED AS WELL...
HOWEVER THE SOUTH FACING BLUE RIDGE WILL LIKELY RECEIVE THE MOST
PRECIPITATION. TEMPERATURES WILL TREND DOWN FROM ABOVE NORMAL TO
NEAR NORMAL AS CLOUDS AND PRECIPITATION INCREASE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 200 PM EDT WEDNESDAY...THE UPPER RIDGE OFF THE SOUTHEAST COAST
WILL MAINTAIN ITS GRIP ON THE CAROLINAS AND GA THROUGH SUNDAY WHILE
BROAD UPPER TROUGHING DOMINATES THE PLAINS AND ROCKIES. WEAKENING OF
THE TROUGH WILL ALLOW AND EAST PACIFIC RIDGE AND THE ATLANTIC RIDGE
TO BRIDGE TOGETHER ON MONDAY. THIS RIDGE OVER THE SOUTHERN TIER OF
STATES STRENGTHENS THROUGH WEDNESDAY...AS THE NORTHERN STREAM TROUGH
PROGRESSES AND WEAKENS FURTHER.

MOIST GULF INFLOW INTO THE SOUTHERN APPALACHIANS WILL CONTINUE ON
SUNDAY AND MONDAY..SUPPORTING PRECIPITATION IN UPSLOPE FLOW INTO THE
SOUTH FACING BLUE RIDGE. GULF INFLOW WEAKENS IN TUESDAY...NEARLY
ENDING BY WEDNESDAY...AS WESTWARD BUILDING SURFACE RIDGING CLOSES
OFF THE GULF. A COLD FRONT WILL APPROACH FROM THE NW ON TUESDAY...
CROSSING OUR AREA LATE ON WEDNESDAY...AND THE ARRIVAL OF THIS
BOUNDARY WILL LEAVE LITTLE OR NO GAP IN PRECIPITATION CHANCES AFTER
THE GULF CLOSES OFF. TEMPERATURES WILL TREND SLIGHTLY HIGHER...FROM
NEAR NORMAL TO A LITTLE ABOVE NORMAL...AS THE UPPER RIDGE
STRENGTHENS.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT AND TERMINALS EAST OF THE MTNS...VFR CONDITIONS ARE FORECAST
TO PERSIST THROUGH THE 6Z TAF PERIOD. CALM TO LIGHT NORTHWEST WINDS
WILL CONTINUE THROUGH SUNRISE. A WEAK BACK DOOR COLD FRONT IS
EXPECTED TO REACH THE VA/NC LINE AROUND 12Z...REMAINING ALONG THE
I-40 CORRIDOR THROUGH THE REMAINDER OF THE TAF PERIOD. BY MID
MORNING...LIGHT WINDS WILL LIKELY BACK FROM THE WEST SOUTHWEST.
DURING THE MID TO LATE AFTERNOON...A FEW SHRA OR TSRA MAY DEVELOP
ACROSS THE FOOTHILLS...COVERAGE TOO LIMITED TO MENTION AT KHKY.

AT KAVL...CLEAR AND CALM CONDITIONS SHOULD FAVOR THE DEVELOPMENT OF
RADIATIONAL FOG WITHIN THE MTN VALLEYS. BASED ON PERSISTENCE...I
WILL USE A TEMPO FROM 9Z-12Z TO HIGHLIGHT LIFR CEILINGS AND IFR VIS.
CONDITIONS SHOULD RETURN TO VFR BY 1330Z.

OUTLOOK...THE AIRMASS WILL MOISTEN OVER THE WEEKEND TO SUPPORT ISOLD
TO SCT DIURNAL THUNDERSTORMS...ESPECIALLY ACROSS THE MTNS. MORNING
LOW CLOUDS AND FOG WILL REMAIN POSSIBLE DURING THE EARLY
MORNING...ESPECIALLY IN THE MTN VALLEYS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-05Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   79%     MED   72%     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...WIMBERLEY
NEAR TERM...NED
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...NED






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