Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 291624
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1224 PM EDT TUE JUL 29 2014

.SYNOPSIS...
CANADIAN HIGH PRESSURE OVER THE AREA WILL DOMINATE THE SURFACE
PATTERN THROUGH MIDWEEK...LEADING TO WELL BELOW NORMAL TEMPERATURES
MORE TYPICAL OF LATE SUMMER OR EARLY AUTUMN. THE SURFACE HIGH WILL
WEAKEN AND MOISTURE WILL RETURN FOR THE WEEKEND...BUT TEMPERATURES
WILL REMAIN BELOW NORMAL.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1215 PM...FORECAST STILL LOOKS ON TRACK. CU DEVEOPING OVER THE
HIGHER TERRAIN BUT NO SBCAPE ANALYZED ON THE SPC MESO ANAL PAGE.
HENCE...STILL THINK THAT CURRENT SLIGHT CHC POPS OVER THE HIGHEST
TERRAIN IN THE MOUNTAINS WILL HOLD DESPITE THE QPF RESPONSE IN
THE 12Z NAM AND GFS. ONLY MINOR CHANGES MADE BASED ON CURRENT
TRENDS.

AS 0F 950 AM...CURRENT FORECAST IS ON TRACK. THE BIGGEST QUESTION IS
WHETHER ANY RIDGE TOP SHOWERS DEVELOP THIS AFTERNOON. ACTUALLY THE
12Z NAM DEVELOPS SOME SHRA OVER THE HIGHER TERRAIN THIS AFTERNOON
AND ADVECTS THEM INTO THE PIEDMONT THIS EVENING. THE QPF RESPONSE
AND THE CAPE IN THE MODEL LOOK WAY OVER DONE AND WILL DISCOUNT THAT
SOLUTION. THE LATEST HRRR HAS A VERY MUTED RESPONSE FOR ANY
MEASURABLE PRECIP. HENCE...WILL JUST MAINTAIN SOME ISOLATED TYPE
POPS MAINLY ALONG THE BLUE RIDGE IN THE GRIDS. MADE SOME MINOR
ADJUSTMENTS TO OTHER FIELDS BASED ON LATEST OBS AND CONSSHORT RUN.

AS OF 530 AM EDT TUESDAY...RATHER NICE MORNING ACROSS THE REGION AS
MOST LOCATIONS ARE REPORTING CLEAR SKIES AND TEMPERATURES IN THE
UPPER 50S TO LOWER 60S.  REMOVED WHAT LITTLE PATCHY FOG THAT WAS IN
THE FORECAST FOR THE MOUNTAIN VALLEYS AS EVEN THE LITTLE TN RIVER
VALLEY REMAINS FOG FREE.  DEWPOINT DEPRESSIONS ACROSS THESE REGIONS
REMAIN IN THE 1-3 DEGREE MARK WITH LIGHT/VRB WINDS.  LATEST
SATELLITE DIFFERENCE PRODUCT INDICATES AREAS OF LOW STRATUS ALONG
THE TN BORDER WITH SCATTERED MID LEVEL STRATUS ACROSS THE NC/SC
PIEDMONT REGIONS THIS MORNING.  TWEAKED TEMPERATURES AND DEWPOINTS
IN THE EXTREME NEAR TERM TO REFLECT LATEST SURFACE OBSERVATIONS AND
LEFT THE REMAINDER OF THE FORECAST AS IS.

PREVIOUS DISCUSSION...

AS OF 300 AM EDT TUESDAY...RATHER PLEASANT NEAR TERM FORECAST AHEAD
FOR NORTHEAST GA...UPSTATE SC...AND WESTERN NC.  BROAD UPPER EASTERN
CONUS TROF WILL REMAIN NEARLY STATIONARY THROUGH THE ENTIRE PERIOD
LEADING TO NO CHANGE IN THE OVERALL PATTERN.  AT THE SURFACE...HIGH
PRESSURE CONTINUES TO DIVE SOUTHWARD ACROSS THE NORTHERN PLAINS AND
INTO THE MID MISSISSIPPI RIVER VALLEY.  CP AIRMASS WILL CONTINUE
TO SPREAD ACROSS THE SOUTHERN/CENTRAL APPS LEADING TO BELOW NORMAL
TEMPERATURES AND DRIER CONDITIONS.  DEWPOINTS ACROSS THE REGION HAVE
ALREADY FALLEN INTO THE UPPER 50S FOR MOST LOCATIONS WITH EVEN MORE
DRYING IN STORE THIS AFTERNOON.  THAT SAID...FORECAST SOUNDINGS
INDICATE A THIN LAYER OF MOISTURE TRAPPED BENEATH LOW/MID LEVEL
INVERSION WHICH WILL LIKELY SATURATE THIS AFTERNOON AMONGST HEATING.
THEREFORE THE FORECAST WILL FEATURE PARTLY CLOUDY SKIES AS FAIR WX
CU PREVAILS.  LASTLY...NORTHERLY WINDS WILL BE WEAKER TODAY VS
YESTERDAY AS PRESSURE GRADIENT HAS RELAXED...AND LOW LEVEL WINDS
REMAIN WEAK THEREBY NEGATING MIXING EFFECTS THIS AFTERNOON.  AS
MENTIONED ABOVE...TEMPERATURES WILL BE RATHER COMFORTABLE TODAY WITH
HIGHS NEARLY A DEGREE OF MAGNITUDE UNDER NORMAL LEVELS.
LIKEWISE...OVERNIGHT LOWS WILL FALL INTO LOWER/MID 60S ACROSS THE
LOW TERRAIN WHILE SOME OF THE HIGHER PEAKS AND RIDGETOPS EXPERIENCE
LOWS IN THE UPPER 40S TO LOWER 50S.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 305 AM...THE WEATHER WILL CONTINUE TO BE DOMINATED BY A DEEP
UPPER TROF OVER THE EASTERN CONUS. A SERIES OF WEAK SHORT WAVES MOVE
THRU THE TROF TAKING THE TROF AXIS EAST OF THE AREA WED...WITH THE
AXIS REBUILDING TO THE WEST ON THU. AT THE SFC...WEAK HIGH PRESSURE
BUILDS INTO THE AREA WED AND REMAINS IN PLACE THU. ALSO ON THU...A
FRONTAL SYSTEM SOUTH AND EAST OF THE GULF AND ATLANTIC COASTS MOVES
NORTH TOWARD THE COAST. ALTHOUGH WARM MID LEVELS WILL KEEP ATMOS
GENERALLY CAPPED...THERE WILL BE ENUF LOW LEVEL MOISTURE AND WEAK
INSTABILITY FOR ISOLATED DIURNAL SHRA TO DEVELOP OVER THE SWRN NC
MTNS. LOW LEVEL S TO SE FLOW INCREASES THU INTO THU NITE AS MID
LEVEL FLOW BECOMES SWLY AND GRADIENT INCREASES BETWEEN THE SFC HIGH
AND APPROACHING FRONTAL SYSTEM. THIS BRINGS INCREASING LOW LEVEL
MOISTURE. DEEP MOISTURE INCREASES AS WELL IN THE DEVELOPING SWLY MID
LEVEL FLOW. UPPER DIVERGENCE DEVELOPS AS THE RIGHT ENTRANCE REGION
OF AN UPPER JET SETS UP OVER THE SERN CONUS. MID LEVEL CAP REMAINS
IN PLACE...BUT WEAKENS ALLOWING WEAK INSTABILITY TO DEVELOP. ALL
THIS WILL LEAD TO AN INCREASED CHC OF SCT SHRA THU INTO THU NITE.
BEST CHC FOR ISOLATED TSRA WILL BE ACROSS THE MTNS WHERE BETTER
INSTABILITY DEVELOPS. QPF WILL GENERALLY BE LIGHT. HIGHS WILL BE
AROUND 10 DEGREES BELOW NORMAL WITH LOW THICKNESSES...INCREASING
CLOUDS...DEVELOPING WEDGE LIKE SFC PATTERN AND POTENTIALLY LIGHT
PRECIP. LOWS WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 320 AM...GUIDANCE SHOWS GENERALLY GOOD AGREEMENT EARLY ON
DURING THE MEDIUM RANGE. UPPER TROF AXIS REMAINS TO OUR WEST FRI AND
SAT AS WEAK SHORT WAVES MOVE ACROSS THE AREA IN THE SWLY FLOW.
HOWEVER...THIS CHANGES BY THE END AS THE GFS KEEPS THE TROF AXIS
WEST OF THE AREA SUN...THEN MOVES IT ACROSS THE AREA MONDAY. THE
ECMWF MOVES IT ACROSS ON SUN WITH THE SUB-TROPICAL RIDGE BUILDING
WEST INTO THE SERN CONUS MONDAY. AT THE SFC...HIGH PRESSURE REMAINS
OVER THE AREA IN A WEDGE LIKE PATTERN FRI AND SAT AS THE FRONTAL
SYSTEM REMAINS NEAR THE COAST. THIS KEEPS THE MOIST S TO SE LOW
LEVEL FLOW ACROSS THE AREA...ALONG WITH THE CHC OF PRECIP. ALTHOUGH
THE GUIDANCE DISAGREES ON THE UPPER PATTERN...THE SFC PATTERN IS
SIMILAR. THE HIGH PRESSURE WEAKENS AND FRONTAL SYSTEM WEAKENS.
HOWEVER...THE MOIST LOW LEVEL SLY FLOW REMAINS IN PLACE...KEEPING
THE CHC OF PRECIP IN PLACE AS WELL. HIGHS REMAIN AROUND 10 DEGREES
BELOW NORMAL...BUT SHOW A SLIGHT WARMING TREND THRU THE PERIOD. LOWS
AROUND 5 DEGREES BELOW NORMAL SLOWLY WARM TO NEAR NORMAL BY THE END
OF THE PERIOD.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
CYCLE.  HIGH PRESSURE AND DOWNSLOPING FLOW WILL DOMINATE THROUGH THE
PERIOD LEADING TO WX FREE CONDITIONS.  MOISTURE TRAPPED BENEATH
LOW/MID LEVEL INVERSION WILL LIKELY CONDENSE BY LATE MORNING INTO
THE AFTERNOON HOURS ACROSS THE REGION LEADING TO FEW/SCT LOW VFR
FAIR WX CU.  WINDS WILL REMAIN IN THE 5-8KTS RANGE AND NORTHERLY
THROUGH THE PERIOD.

OUTLOOK...DRY HIGH PRESSURE PREVAILS THROUGH WEDNESDAY WITH THE ONLY
POSSIBLE RESTRICTIONS BEING POTENTIAL EARLY MORNING FOG/STRATUS IN
THE MOUNTAIN VALLEYS.  INCREASING MOISTURE ON THURSDAY AND INTO
FRIDAY WILL YIELD ENHANCED PRECIPITATION/FOG/STRATUS CHANCES INTO
THE WEEKEND.

CONFIDENCE TABLE...

            16-22Z        22-04Z        04-10Z        10-16Z
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  95%
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...LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CDG






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