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000
FXUS62 KGSP 160719
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
319 AM EDT THU MAY 16 2013

.SYNOPSIS...
A WARM AIR MASS WILL REMAIN OVER THE REGION THROUGH THE REST OF THIS
WEEK. CONDITIONS WILL BECOME MORE UNSETTLED AS A MID LEVEL
DISTURBANCE RIPPLES ACROSS THE CAROLINAS LATE THIS WEEKEND. A COLD
FRONT WILL SLOWLY APPROACH THE SOUTHERN APPALACHIANS DURING THE
MIDDLE PART OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM EDT...WATER VAPOR IMAGERY SHOWS A 500 MB LOW CENTER
MEANDERING EAST ACROSS ERN OK EARLY THIS MORNING. THIS FEATURE WILL
GRADUALLY OPEN UP AND CONTINUE MOVING EAST...STEADILY BREAKING DOWN
THE RIDGE OVER THE APPALACHIANS AND SPREADING MID AND HIGH LEVEL
CLOUDS INTO THE FORECAST AREA. SCATTERED CONVECTION SHOULD DEVELOP
FIRST TODAY OVER THE SW MTNS OF NC WHERE A LOW LEVEL SW UPSLOPE FLOW
AND WEAK VORT MAXIMA ALOFT WILL PROVIDE TRIGGERING. SOME CONVECTIVE
INHIBITION REMAINS IN MODEL PROFILES TODAY...BUT THIS SHOULD BE
OVERCOME IN THE MTNS WITH THE WEAK FORCING...WITH A FEW STRONG TSTMS
THEN POSSIBLE IN THE FAIRLY STEEP LAPSE RATES ALOFT. WESTERLY
STEERING FLOW WILL CARRY SCATTERED MTN CONVECTION INTO THE FOOTHILLS
THIS AFTERNOON...AND ISOLD COVERAGE MAY SURVIVE EAST INTO THE
PIEDMONT LATE IN THE DAY. DESPITE THE INCREASING CLOUDS...EXPECT
MAXES 5 DEGREES OR MORE ABOVE NORMAL.

ALTHOUGH THE CONVECTION WILL WANE WITH THE LOSS OF DAYTIME HEATING
TONIGHT...ISOLATED SHOWERS COULD LINGER OVERNIGHT OVER THE NC MTNS
AS WEAK ENERGY AHEAD OF THE OPENING UPPER LOW PUSHES INTO THE
APPALACHIANS. EXPECT WARM MINS UNDER THE CLOUD COVER...WITH MAINLY
50S MTNS AND LOWER 60S PIEDMONT.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 235 AM THURSDAY...ON FRIDAY...THE MID LEVEL HEIGHTS WILL
FEATURE SLIGHT RIDGING ACROSS THE CWA AS A BROAD LOW TRACKS OVER THE
LOWER OHIO RIVER VALLEY. AT H7...RIDGING IS SLIGHTLY BETTER
DEFINED...WITH THE CENTER OF THE H7 HIGH OFF THE COAST OF SC. AT THE
SFC...A STATIONARY FRONT WILL TRACK GENERALLY WEST TO EAST ACROSS
THE VIRGINIAS DURING THE AFTERNOON. FORECAST SOUNDINGS INDICATE THAT
MOISTURE WILL INCREASE AHEAD OF THE MID LEVEL TROF...PW VALUES
RANGING ACROSS THE CWA FROM 1.25 TO 1.5 INCHES. TEMPERATURES BELOW
H5 WILL REMAIN VERY MILD...LIMITING CAPE VALUES LESS THAN 1000 J/KG.
THE INCREASE IN LLVL MOISTURE SHOULD KEEP CIN FAIRLY WEAK AND
SHALLOW DURING THE AFTERNOON. GIVEN THE APPROACH OF THE MID LEVEL
TROF...BROAD FIELD OF INSTABILITY...AND DEEP MOISTURE...I WILL
FORECAST LIKELY POPS ACROSS THE MTNS AND CHC EAST FOR SHRA/TSRA. MOS
CONSENSUS SUPPORTS HIGHS FROM AROUND 80 AT KAVL TO MID TO UPPER 80S
EAST OF THE MTNS.

SATURDAY...THE FORCING ASSOCIATED WITH THE MID LEVEL TROF WILL FAVOR
A TRACK NE ALONG THE OHIO RIVER VALLEY. DEEP CONVECTION ACROSS THE
FORECAST AREA SHOULD GRADUALLY ASHE OUT EARLY SATURDAY
MORNING...WITH MIN POP EXPECTED AROUND 20 PERCENT. BY SATURDAY
AFTERNOON...THE MAIN WEATHER FEATURES WILL REMAIN COMPARABLE TO
FRIDAY. FORECAST SOUNDINGS ACROSS THE CWA INDICATE
INSTABILITY/STABILITY VALUES VERY CLOSE TO FRIDAY. GIVEN THE
SIMILARITY TO FRI...I WILL USE PERSISTENCE FOR THE PEAK POP DURING
THE MID AFTERNOON PERIOD. HIGH TEMPERATURE MAY VERIFY 2 TO 3 DEGREES
COOLER THAN FRIDAY...WITH DEWPOINTS 2 TO 4 DEGREES HIGHER.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...I WILL USE A BLEND OF THE GFS AND ECMWF
THROUGH THE MEDIUM RANGE. SUNDAY APPEARS TO BE THE DAY OF PEAK
COVERAGE OF SHRA AND TSRA ACROSS THE FORECAST AREA. BY SUNDAY
AFTERNOON INTO THE EARLY EVENING...GUIDANCE INDICATES THAT THE BOUNDARY
THAT LINGERED OVER THE VIRGINAS EARLIER IN THE WEEKEND WILL PUSH
INTO THE I-40 CORRIDOR. ALOFT...H7 TO H5 TROF AXIS AND VORT MAX WILL
RIPPLE OVER THE SOUTHERN APPALACHIANS...COOLING MID TROPOSPHERE
TEMPERATURES A DEGREE OR TWO. IN ADDITION...PW VALUES ACROSS THE CWA
WILL RANGE GENERALLY ABOVE 1.5 INCHES. THE COMBINATION PASSING
VORT...STEEPING LAPSE RATES...INCREASING MOISTURE SHOULD SUPPORT
LIKELY MTN POPS WITH HIGH CHC TO SOLID CHC EAST OF THE MTNS. HIGH
TEMPERATURES MAY RANGE WITHIN A COUPLE OF DEGREES OF NORMAL.

MON THROUGH WED...THE ENVIRONMENT ACROSS THE CWA WILL SEE A GRADUAL
REDUCTION IN PW VALUES AS S/W RIDGING BUILDS EAST ACROSS THE
APPALACHIANS. THE FORECAST AREA IS EXPECTED TO REMAIN ON THE WESTERN
EDGE OF A BERMUDA HIGH. ON WED...A COLD FRONT WILL APPROACH THE
REGION FROM THE WEST...BUT IS NOT EXPECTED TO ARRIVE OVER THE REGION
UNTIL WED NIGHT/EARLY THURSDAY. THIS PATTERN SHOULD BE VERY
FAVORABLE TO DIURNAL AIR MASS SHRA/TSRA. I WILL FORECAST A PEAK OF
CHC POPS DURING THE HEAT OF THE AFTERNOON...FADING TO SCHC OR LESS
DURING THE EARLY MORNING HOURS. TEMPERATURES WILL RANGE FROM NORMAL
TO 2 TO 3 DEGREES ABOVE.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
AT KCLT...MID AND HIGH CLOUDS WILL INCREASE THROUGH THE PERIOD AS AN
UPPER LEVEL LOW PRESSURE SYSTEM BREAKS DOWN THE RIDGE FROM THE WEST.
SCATTERED MOUNTAIN CONVECTION TODAY COULD MAKE A RUN EASTWARD IN THE
WESTERLY STEERING FLOW...BUT THERE IS ONLY A SLIGHT CHANCE OF IT
SURVIVING EAST TO KCLT LATE DAY. IF IT DID...IT WOULD PROBABLY
IMPACT THE AIRFIELD 22Z TO 00Z. SW WINDS WILL INCREASE WITH MIXING
TODAY BUT REMAIN GENERALLY 10 KT OR LESS WITH ONLY LIMITED GUSTS.

ELSEWHERE...MID AND HIGH CLOUD CEILINGS WILL DEVELOP AND PERSIST
THROUGH THE PERIOD AS A 500 MB LOW CENTER OPENS UP TO THE W.
SCATTERED CONVECTION SHOULD DEVELOP OVER THE SW NC MTNS BY MIDDAY
AND STEER E...WITH THE BEST CHANCE OF THUNDER AT KAVL. SCT ACTIVITY
WILL LIKELY SPILL OUT INTO THE FOOTHILLS DURING THE AFTN...WITH
PROB30 FEATURED FOR TSRA FROM KGMU TO KGSP...AND MAINLY VCSH NEAR
KHKY. ANTICIPATE STEADY SW FLOW THROUGH THE PERIOD AT MAINLY 5 TO 10
KT...WITH ISOLATED LOW END GUSTS POSSIBLE DURING AFTERNOON MIXING.

OUTLOOK...SHOWER AND THUNDERSTORM COVERAGE...AND ASSOCIATED
RESTRICTIONS...WILL GRADUALLY INCREASE FRIDAY THROUGH MONDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-07Z
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...NED
NEAR TERM...HG
SHORT TERM...NED
LONG TERM...NED
AVIATION...HG