000
FXUS62 KGSP 150535
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
135 AM EDT WED MAY 15 2013

.SYNOPSIS...
HIGH PRESSURE WILL PUMP WARM MOIST AIR OVER THE REGION THROUGH
WEDNESDAY..AHEAD OF A MID LEVEL DISTURBANCE THAT IS EXPECTED TO
RIPPLE OVER THE SOUTHERN APPALACHIANS ON THURSDAY. HIGH SHIFTS OFF
THE CAROLINA COAST FOR THE WEEKEND AS A COLD FRONT APPROACHES FROM
THE WEST DURING THE EARLY PART OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 AM EDT...A FLAT RIDGE WILL PERSIST OVER THE AREA TODAY AS
A CLOSED LOW PRES SYSTEM MOVES SLOWLY E ACROSS THE SOUTHERN PLAINS.
FAIRLY STOUT WESTERLY 850 MB FLOW OVER THE RIDGE AXIS WILL IMPACT
THE HIGHEST ELEVATIONS OF THE NC MTNS THIS MORNING. HOWEVER...WINDS
SHOULD NOT MIX DOWN TO THE MID SLOPES OR LOWER VALLEYS IN THIS WARM
ADVECTION REGIME. THE WESTERLY FLOW WILL PRODUCE DOWNSLOPE WARMING
EAST OF THE MTNS...WITH A LEE TROUGH LIKELY DEVELOPING. A FEW SREF
MEMBERS AS WELL AS THE OPERATIONAL GFS HAVE ISOLATED SHOWERS LATE
TODAY IN THE LEE TROUGH AXIS. MODEL PROFILES INDICATE FAIRLY DECENT
SFC BASED CAPE VALUES AROUND 1000 J/KG. HOWEVER...LOW LEVEL
CONVERGENCE IN THE LEE TROUGH SHOULD BE TOO WEAK TO PROVIDE MUCH
TRIGGERING GIVEN THE RELATIVELY HIGH LFC HEIGHTS. MAX TEMPS WILL
SURGE TO 7 TO 10 DEGREES ABOVE NORMAL IN MOST LOCATIONS THIS AFTN.

THE H5 LOW WILL MEANDER INTO THE MID MS RIVER VALLEY TONIGHT...WITH
ALL ATTENDANT SHORTWAVE ENERGY STAYING W OF THE FORECAST AREA
THROUGH THE PERIOD. EXPECT MAINLY AN INCREASE IN HIGH CLOUDS FROM
THE W OVERNIGHT...WITH MIN TEMPERATURES 1 TO 2 CATEGORIES ABOVE
NORMAL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 215 PM TUESDAY...A FLAT UPPER RIDGE INITIALLY OVER THE AREA
WILL MOVE EAST ON THU AS A WEAKENING UPPER TROUGH APPROACHES AND
THEN MOVES EAST OF THE AREA THU NIGHT. AS THE TROUGH REACHES THE
AREA THU...THE LOWERING UPPER HEIGHTS SHOULD BE SUFFICIENT TO
ALLOW FOR CONVECTIVE INITIATION DURING THE AFTERNOON HOURS. THE
CONVECTION SHOULD FAVOR THE HIGH TERRAIN OVER WESTERN NC AND NE
GA. EAST OF THE MOUNTAINS...FORECAST SOUNDINGS SHOW QUITE A BIT OF
CIN TO OVERCOME IN THE LOWER LEVELS OF THE COLUMN ON THU. THIS
SHOULD LIMIT ANY CONVECTION OUTSIDE THE MOUNTAINS TO JUST ISOLATED
TO WIDELY SCATTERED COVERAGE. THE CONVECTION IS EXPECTED TO WANE
THU EVENING AS THE TROUGH MOVES EAST AND THE ATMOSPHERE COOLS.
MODEL TIME HEIGHTS SHOW THAT MOISTURE INCREASES SUBSTANTIALLY
THROUGH THE COLUMN ON FRIDAY WHICH WILL RESULT IN MORE CLOUDINESS.
ALSO...WEAK UPSLOPE FLOW WILL PRODUCE SCATTERED AFTERNOON SHOWERS
AND THUNDERSTORMS OVER THE MOUNTAINS...WITH A FEW MOVING OUT OVER
THE FOOHILLS AND PIEDMONT DURING THE LATE AFTEROON HOURS. TEMPS
WILL BE QUITE WARM ON THU WHERE A BLEND OF GUIDANCE PRODUCES MAX
TEMPS IN THE MID TO UPPER 80S OUTSIDE OF THE MOUNTAINS...AND LOW
80S MOUNTAIN VALLEYS. MORE CLOUDS ON FRIDAY WILL SERVE TO TRIM A
FEW DEGREES OFF MAX TEMPS WITH HIGHS IN THE LOW TO MID 80S OUTSIDE
OF THE MOUNTAINS AND 75 TO 80 MOUNTAIN VALLEYS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 145 PM TUESDAY...A WEAK UPPER RIDGE IS FORECAST TO PREVAIL
FROM THE GULF OF MEX...NE THROUGH THE TN VALLEY SAT THROUGH SUN. THE
RIDGE IS THEN EXPECTED TO MOVE TO THE EAST COAST ON MON AS AN UPPER
TROUGH DEVLOPS OVER THE CENTRAL PORTION OF THE COUNTRY. AT THE
SURFACE...THE WESTERN EXTENSION OF THE WESTERN ATLANTIC SUBTROPICAL
RIDGE WILL DOMINATE THROUGH THE PERIOD. A BACKDOOR COLD FRONT EARLY
IN THE WEEKEND IS EXPECTED TO STALL SOMEWHERE OVER EASTERN NC AND
THEN MOVE NORTH AS A WARM FRONT. THEREFORE...THE FORECAST WILL
FEATURE WARM TEMPERATURES AND MAINLY DIURNAL CONVECTION FAVORING THE
MOUNTAINS. A MCS STILL CAN NOT BE COMPLETELY RULED OUT IN THE SAT
NIGHT TIMEFRAME AS AN UPPER PULSE MOVES OVER THE UPPER RIDGE.
HENCE...HAVE MAINTAINED SOME LOW CHANCE POPS OVER NORTHERN SECTIONS
SAT NIGHT. OTHERWISE...JUST SCATTERED TYPE POPS ARE FORECAST EACH
AFTERNOON AND EVENING. TEMPS ARE FORECAST TO BE ABOUT A CATEGORY
ABOVE AVERAGE EACH DAY.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL CONTINUE THROUGH THE TAF
PERIOD. WESTERLY FLOW OVER THE MTNS WILL HELP TO ESTABLISH A LEE
TROUGH EAST OF THE BLUE RIDGE TODAY...WITH WINDS ADJUSTING TO SW AT
THE FOOTHILLS TAF SITES AS WELL AS KCLT. LOW END GUSTS OF 17 TO 19
KT ARE EXPECTED WITH PEAK MIXING THIS AFTN. MAINLY FEW TO SCT MID
AND HIGH CLOUDS ARE EXPECTED...BUT HIGH BASED CONVECTIVE CUMULUS MAY
DEVELOP IN THE LEE TROUGH CONVERGENCE AXIS THIS
AFTERNOON...ESPECIALLY FROM KGSP TO KCLT. EXPECT LIGHT SW FLOW
TONIGHT...WITH HIGH CLOUDS INCREASING FROM THE W.

OUTLOOK...VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE REST OF
THE WEEK. HOWEVER...SCATTERED AFTN AND EVENING THUNDERSTORMS WILL BE
POSSIBLE FROM THURSDAY THROUGH THE WEEKEND.

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       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...PAT
NEAR TERM...HG
SHORT TERM...LG
LONG TERM...LG
AVIATION...HG