Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 270604
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
204 AM EDT WED AUG 27 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO BRING MOSTLY DRY CONDITIONS TO THE
REGION TONIGHT INTO THURSDAY. MOISTURE AND TEMPERATURES WILL
GRADUALLY INCREASE THIS WEEKEND INTO EARLY NEXT WEEK AS A BERMUDA
HIGH PRESSURE REDEVELOPS.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 2 AM...I WILL UPDATE THE FORECAST TO MAKE SMALL CHANGES IN
NEAR TERM SKY AND TEMPS. IN ADDITION...I HAVE ADDED A MENTION OF
DAWN FOG ACROSS THE UNIFOUR...DECREASED THE DENSITY OF FOG WITHIN
THE MTN VALLEYS.

AS OF 1025 PM EDT TUESDAY...SCATTERED TO BROKEN LOW LEVEL STRATUS
HAS EXPANDED IN DEPTH/COVERAGE ACROSS PORTIONS OF THE BLUE RIDGE
ESCARPMENT.  THIS SKY COVER WAS EXPECTED HOWEVER HAS DEVELOPED A FEW
HOURS AHEAD OF SCHEDULE.  THUS...MADE ADJUSTMENTS TO SKY GRIDS
OVERNIGHT BY BLENDING IN LATEST NAM WHICH SEEMS TO HAVE A GOOD READ
ON THE CURRENT SITUATION.  OTHERWISE...NORTHERLY WINDS HAVE ALL BUT
CALMED AT MOST SITES AND WILL REMAIN LIGHT/CALM THROUGH THE
OVERNIGHT.  TEMPERATURES ARE COOLING OFF RATHER NICELY AMIDST MOSTLY
CLEAR SKIES AS MOST PIEDMONT/FOOTHILLS SITES ARE ALREADY IN THE
LOWER 70S WITH THE MOUNTAIN LOCATIONS IN THE MID TO UPPER 60S.
OTHERWISE...TWEAKED TEMPERATURES AND DEWPOINTS IN THE EXTREME NEAR
TERM AND LEFT THE REMAINDER OF THE FORECAST UNCHANGED.

PREVIOUS DISCUSSION...

AT 200 PM EDT TUESDAY...AN UPPER RIDGE FROM THE MID ATLANTIC REGION
TO NORTHERN MEXICO WILL START TO BREAK DOWN OVER THE CAROLINAS ON
WEDNESDAY AS TROPICAL SYSTEM CRISTOBAL MOVES NORTH OFF THE EAST
COAST. DRY SURFACE HIGH PRESSURE OVER THE CAROLINAS AND GA WIL
PERSIST...BUT WEAKEN. DUE TO THE MOTION OF CRISTOBAL...SURFACE
WINDS WILL BACK FORM NE TO N OVERNIGHT...INTRODUCING A LIGHT
DOWNSLOPE FLOW IN A WEAK PRESSURE GRADIENT. MODEL TIME HEIGHTS SHOW
THE LIMITED MOISTURE NOW AROUND 900 MB LARGELY DIMINISHING BY
DAYBREAK. MINIMUM TEMPERATURES TONIGHT WILL RUN AROUND SEVEN DEGREES
BELOW NORMAL...AND MAXIMUM TEMPERATURES ON WEDNESDAY NEAR NORMAL.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 215 PM TUESDAY...DRY HIGH PRESSURE WILL CONTROL THE WEATHER
OVER THE REGION WED NIGHT THROUGH THU MORNING. WITH THE AXIS OF THE
UPPER RIDGE REMAINING WEST OF THE AREA AND STRONG SHORT WAVE ENERGY
MOVING THROUGH NEW ENGLAND ON THU...A BACKDOOR FRONT WILL MAKE A RUN
AT THE AREA. THE 12Z MODEL RUNS  HAVE COME INTO BETTER AGREEMENT
THAT THE BOUNDARY WILL REACH I-40 CORRIDOR INTO SRN VA ON BY LATE
THURSDAY. ALL THE MODELS SHOW SOME QPF RESPONSE IN THE VICINITY OF
THE FRONT AND OVER THE NC MOUNTAINS AS CAPES INCREASE TO PERHAPS
1000J/KG OR MORE. HENCE...WILL CONTINUE WITH THE IDEA THAT WIDELY
SCT/SCT THUNDERSTORMS WILL DEVELOP FROM THE NC MOUNTAINS...EASTWARD
ACROSS AND NORTH OF THE I-40 CORRIDOR. WITH THE LOSS OF DAYTIME
HEATING...EXPECT CONVECTION TO WANE THU EVENING. AS THE UPPER RIDGE
RE-ASSERTS ITSELF ON FRIDAY...DRY CONDITIONS ARE EXPECTED. MAX TEMPS
WILL BE A CATEGORY OR MORE ABOVE NORMAL BOTH THURSDAY AND FRIDAY.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 200 PM TUESDAY...AN UPPER RIDGE WILL REMAIN OVER THE SE U.S.
THROUGH TUE BUT DE-AMPLIFY SOMEWHAT THE FIRST PART OF NEXT WEEK AS
SHORT WAVE ENERGY MOVES THROUGH THE OHIO VALLEY. AT THE SURFACE...
THE BERMUDA HIGH WILL DOMINATE. CURRENT MODEL GUIDANCE SUGGESTS THAT
SATURDAY SHOULD BE GENERALLY DRY ACROSS THE AREA WITH DEEP LAYER
HIGH PRESSURE DOMINATING. THE EXCEPTION MAY BE THE SW NC MOUNTAINS
AND NE GA MOUNTAINS WHERE UPSLOPE FLOW MAY TRIGGER SOME SCT
AFTERNOON CONVECTION. PRECIP CHANCES WILL IMPROVE ON SUNDAY AS
MOISTURE INCREASES AND UPPER HEIGHTS FALL SOMEWHAT. CURRENT GUIDANCE
SUGGESTS NUMEROUS SHOWERS/STORMS FOR THE MOUNTAINS AND SCT ELSEWHERE
ON SUNDAY. WILL ADVERTISE NEAR CLIMO POPS FOR SCT DIURNAL CONVECTION
BOTH MONDAY AND TUE AS THE BERMUDA HIGH REMAINS IN PLACE OVER THE SE
STATES. TEMPS WILL BE ABOUT A CATEGORY OR SO ABOVE AVERAGE THROUGH
THE PERIOD.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...VFR VIS AND SKY. THROUGH THE 6Z TAF PERIOD...THE SFC
PATTERN WILL FEATURE WEAK HIGH PRESSURE ACROSS THE SOUTHERN
APPALACHIANS WITH CRISTOBAL ACROSS THE WESTERN ATLANTIC. THE SFC
PATTERN WILL SUPPORT WIND DIRECTIONS BETWEEN 310-010 DEGREES ACROSS
KCLT. SPEEDS WILL REMAIN 5 KTS OR LESS...POSSIBLY CALM DURING THE
NIGHT.

ELSEWHERE...EAST OF THE MTNS...CONDITIONS SHOULD FOLLOW CLT EXAMPLE.
MTN VALLEY AREAS...LATEST RUN OF MOS INDICATES A WEAK CASE FOR FOG
AND LOW CEILINGS EARLY THIS MORNING. HOWEVER...CALM AND CLEAR
CONDITIONS SHOULD ALLOW DEWPOINTS DEPRESSIONS TO CLOSE IN DURING THE
PRE DAWN HOURS. I WILL HIGHLIGHT LIFR CONDITIONS WITH A TEMPO FROM
11Z-13Z. AFTER 13Z...VFR CONDITIONS WITH LIGHTS WILL PREVAIL.

OUTLOOK...THE AIRMASS WILL MODIFY MID TO LATE WEEK TO GRADUALLY
SUPPORT RETURNING ISOLD TO SCT DIURNAL THUNDERSTORMS...ESPECIALLY
ACROSS THE MTNS. MORNING LOW CLOUDS AND FOG WILL BE POSSIBLE...
ESPECIALLY IN THE MTN VALLEYS.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH  95%     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...JOH
NEAR TERM...NED
SHORT TERM...LG
LONG TERM...LG
AVIATION...NED






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.