Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 111728
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
128 PM EDT FRI APR 11 2014

.SYNOPSIS...
A WARM SOUTHERLY FLOW OF AIR IS STILL EXPECTED TO CONTINUE THROUGH
THE WEEKEND. MOISTURE AHEAD OF AN APPROACHING COLD FRONT IS EXPECTED
TO OVERSPREAD THE REGION ON MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 120 PM EDT FRIDAY...CONTINUED WARMTH AMIDST PARTY CLOUDY SKIES
HAS MADE FOR A NICE BREEZY DAY ACROSS THE REGION.  ADJUSTED
TEMPERATURES AND DEWPOINTS TO REFLECT LATEST OBSERVATIONS AND LEFT
THE REMAINDER OF THE FORECAST AS IS FOR THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 330 AM...TODAY...HIGH PRESSURE WILL REMAIN CENTERED OFF THE
SOUTHEAST COAST AS A WEAK COLD FRONT APPROACHES FROM THE NORTHWEST.
THIS PATTERN WILL SUPPORT STEADY SOUTHWEST FLOW...RESULTING IN WEAK
WAA. THE WARM THICKNESSES COMBINED WITH STRONG INSOLATION SHOULD
RESULT IN HIGH TEMPERATURES AROUND 5 DEGREES ABOVE NORMAL...OR LOW
70S ACROSS THE MTN VALLEYS TO THE UPPER 70S ACROSS THE FOOTHILLS AND
PIEDMONT. AFTERNOON DEWPOINTS SHOULD RANGE FROM THE LOW TO MID
40S...YIELDING RH VALUES IN THE UPPER 20S. IN ADDITION...SOUTHWEST
WINDS WILL LIKELY DEVELOP MARGINAL GUSTS FROM LATE MORNING THROUGH
EARLY EVENING.

TONIGHT...NEAR TERM MODELS INDICATE THAT THE WEAK COLD FRONT WILL
REACH THE SOUTHERN APPALACHIANS AROUND 6Z. INTERESTINGLY...BOTH THE
NAM AND GFS INDICATE LITTLE TO NO CAPE ACROSS THE CWA...WITH SHRA
GENERALLY DISSIPATING IN THE WAKE OF THE CUMBERLAND PLATEAU. I WILL
REDUCE POPS TO A SCHC ACROSS THE TN BORDER...WITH LESS THAN 0.05 OF
AN INCH EXPECTED. LOW TEMPERATURES ARE FORECAST TO RANGE FROM THE
MID 40S ACROSS THE MTNS TO THE LOW 50S ACROSS THE PIEDMONT.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 200 AM FRIDAY...RIDGING SFC AND ALOFT WILL REMAIN OVER THE ERN
CONUS THRU THE PERIOD. THAT SAID...A SHORT WAVE DOES APPROACH THE
CWFA SUN NITE. A SLY SFC AND LOW LEVEL FLOW REMAINS ACROSS THE AREA
THRU THE PERIOD AS WELL. LOW LEVEL MOISTURE LINGERS ACROSS THE AREA
BUT INSTABILITY IS QUITE LIMITED. GUIDANCE DISAGREES ON THE
DEVELOPMENT OF ANY CONVECTION DURING THIS PERIOD. MDL BLEND KEEPS
THE AREA DRY THRU SUNDAY...SO HAVE FOLLOWED THIS TREND AS WELL. THAT
CHANGES SUN NITE AS THE SHORT WAVE MOVES IN ALONG WITH DEEPER
MOISTURE. SHUD BE ENUF UPSLOPE FLOW TO ACT ON THE INCREASING
MOISTURE FOR ISOLATED SHRA TO DEVELOP ALONG THE LENGTH OF THE BLUE
RIDGE. HIGHS AND LOWS WILL BE AROUND 10 DEGREES ABOVE NORMAL THRU
THE PERIOD.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 330 AM FRIDAY...MEDIUM RANGE GUIDANCE REMAINS IN OVERALL
AGREEMENT...BUT DETAIL DIFFERENCE CONTINUES. INITIAL SHORT WAVES
CROSS THE AREA MONDAY AS A DEEP CENTRAL CONUS TROF DEVELOPS. THIS
TROF MOVES TOWARD THE AREA AND CROSSES THE AREA TUE NITE OR WED...
DEPENDING ON THE AMOUNT OF NRN AND SRN STREAM PHASING. GUIDANCE ALSO
AGREES ON INCREASING DEEP MOISTURE AND SLY FLOW AHEAD OF AN
APPROACHING COLD FRONT MONDAY. THE FRONT MOVES INTO THE AREA MONDAY
NITE AND ACROSS THE AREA TUE. WAVES FORM ALONG THE FRONT AS IT
CROSSES THE AREA. THE ECMWF HAS SLIGHTLY STRONGER WAVES AND A SLOWER
MOVEMENT THAN THE GFS. HOWEVER...THE GFS IS RELATIVELY SLOW AS WELL.
FCST SOUNDINGS SHOW WEAK INSTABILITY AND SHEAR WITH THIS SYSTEM...
KEEPING THE CHC OF ORGANIZED SEVERE STORMS LOW. WITH THE SLOW
MOVEMENT EXCESSIVE QPF/FLOODING COULD BE AN ISSUE...BUT IS STILL
UNCERTAIN. CANNOT RULE OUT SOME NW FLOW SNOW FOR THE MTNS AS THE
PRECIP ENDS TUE NITE. HOWEVER...CHC OF ANY ACCUMS ARE LOW. COLD HIGH
PRESSURE BUILDS IN BEHIND THE FRONT FOR WED AND THU.

NEAR NORMAL HIGHS MONDAY FALL TO AROUND 10 DEGREES BELOW NORMAL BY
WED AND THU. LOWS AROUND 10 DEGREES ABOVE NORMAL MON NITE FALL TO 5
TO 10 DEGREES BELOW NORMAL BY THE END OF THE PERIOD. THESE LOWS
WOULD INDICATE A FROST/FREEZE POTENTIAL FOR THE I-40 CORRIDOR...AND
THE CENTRAL AND SRN NC MTNS...ALONG WITH THE NE GA AND SC MTNS. THE
FROST/FREEZE SEASON BEGINS APRIL 15 FOR ALL BUT THE NRN MTNS.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES
THROUGH THE PERIOD.  MIXING ALONG WITH INCREASING PRESSURE GRADIENT
FORCES AHEAD OF AN APPROACHING SURFACE COLD FRONT WILL WARRANT
CONTINUATION OF WIND GUSTS AT ALL SITES THROUGH THE REMAINDER OF THE
DAY WITH THE EXCEPTION OF KAVL WHERE RELATIVELY LIGHTER WINDS WILL
PREVAIL.  WINDS WILL DECREASE OVERNIGHT AS THE PRESSURE GRADIENT AND
MIXING RELAX.  ALL TAF SITES WILL REMAIN DRY WITH THIS FROPA.
MID/HIGH LEVEL CIRRUS WILL PREVAIL THROUGH THE OVERNIGHT WITH LOW
LEVEL FAIR WX CU DEVELOPING BY LATE MORNING AT ALL SITES AS
PERSISTENT SOUTHWEST FLOW ADVECTS MOISTURE INTO THE BOUNDARY LAYER.
LIGHT/CALM OVERNIGHT WINDS WILL INCREASE OUT OF THE SOUTH BY LATE
MORNING SATURDAY DESPITE THE WEAK FROPA.

OUTLOOK...HIGH PRESSURE WILL REMAIN ACROSS THE TERMINALS THROUGH THE
WEEKEND. A LOW PRESSURE SYSTEM WILL ORGANIZE ACROSS THE DEEP SOUTH
EARLY NEXT WEEK. MOISTURE AND LIFT ASSOCIATED WITH THIS SYSTEM WILL
LIKELY YIELD RESTRICTIVE CONDITIONS FROM EARLY MON MORNING THROUGH
TUESDAY.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-17Z
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 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...RWH
NEAR TERM...CDG/NED
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CDG






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