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000
FXUS62 KGSP 140227
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1027 PM EDT THU JUN 13 2013

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA LATE THIS AFTERNOON THROUGH THIS
EVENING. DRY HIGH PRESSURE WILL BUILD IN FROM THE NORTH BEHIND THE
FRONT FRIDAY...AND SETTLE ACROSS THE REGION THROUGH THE WEEKEND. THE
NEXT COLD FRONT WILL APPROACH FROM THE NORTHWEST BY THE MIDDLE OF
NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 1025 PM...LAST OF THE CONVECTION HAS MOVED SOUTH AND EAST OF
THE CWFA. A FEW VERY LIGHT SHRA WILL MOVE INTO THE MTNS LATE THIS
EVENING AND DISSIPATE SHORTLY AFTER MIDNIGHT. SKIES WILL BEGIN TO
CLEAR OUTSIDE OF THE MTNS AS CONVECTIVE DEBRIS FROM THE MCS MOVES
SOUTH AND EAST AS WELL. CLOUDS WILL LINGER OVER THE MTNS A LITTLE
BIT LONGER THEN DISSIPATE BY DAYBREAK. STILL EXPECT MTN VALLEY FOG
TO DEVELOP. CANNOT RULE OUT FOG ELSEWHERE...BUT CHC TO LOW TO
INCLUDE FOR NOW. OTHERWISE...UPDATES WERE MAINLY FOR CURRENT
CONDITIONS.

AS OF 8 PM...WILL EXTEND THE WATCH FOR 1 HOUR ALONG THE SRN TIER OF
THE CWFA WHERE STORMS CONTINUE. THE LINE SHOULD FINALLY BE SOUTH OF
THE AREA BY 9 PM...ALTHOUGH IT COULD SLOW SLIGHTLY WITH SOME
LINGERING SHRA FOR ANOTHER HOUR. SOME SCT SHRA WILL MOVE SOUTH INTO
THE TN BORDER COUNTIES BEFORE MIDNIGHT...BUT SHOULD DISSIPATE BEFORE
MOVING TOO FAR SE. OTHERWISE...EXPECT SLOWLY CLEARING SKIES WITH
DIMINISHING WINDS. WINDS COULD PICK BACK UP OVER THE MTNS AFTER
MIDNIGHT HOWEVER. EVEN IF THE WINDS DO INCREASE...LIKELY NOT ENUF TO
KEEP PATCHY VALLY FOG FROM FORMING.

AS OF 225 PM EDT THURSDAY...SEVERE STORMS ARE JUST BEGINNING TO MOVE
INTO THE NC MTNS. WESTERLY WINDS HAVE INCREASED TO AROUND 50 KTS AT
10KFT ACROSS THE REGION...WITH 0-3KM BULK SHEAR VALUES GENERALLY
RANGING BETWEEN 30-40 KTS. DCAPE VALUES ARE HIGH AND THE ATMOSPHERE
IS SUPPORTIVE OF STRONG COLD-POOL GENERATION. THEREFORE I EXPECT THE
LINE TO SURVIVE IT/S TRIP ACROSS THE MOUNTAINS AND DEVELOP QUICKLY
INTO A SQUALL LINE OVER OR JUST EAST OF THE BLUE RIDGE. THIS SHOULD
RESULT IN WIDESPREAD STRAIGHT-LINE WIND DAMAGE ACROSS THE FORECAST
AREA AS IT RAPIDLY MOVES OFF TO THE EAST-SOUTHEAST. THIS FIRST ROUND
OF STORMS MAY MISS THE SOUTHWEST MOUNTAINS AND EXTREME NORTHEAST
GEORGIA TO THE EAST...THOUGH I WOULD EXPECT ADDITION CONVECTION TO
DEVELOP UPSTREAM AND AFFECT THESE AREAS DURING THE EARLY EVENING
HOURS. BY LATE EVENING THINGS WILL QUIET DOWN CONSIDERABLY AS COLD
FRONT CROSSES THE REGION. FOR FRIDAY IT WILL BE SUNNY AND MUCH LESS
HUMID.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EDT THURSDAY...AN UPPER TROUGH WILL BE ALONG THE EAST
COAST ON FRIDAY EVENING...WHILE AN UPPER RIDGE WILL BE OVER THE
LOWER MS RIVER VALLEY. ON SATURDAY THE TROUGH PROGRESSES FARTHER
OFFSHORE...WHILE THE RIDGE BROADENS ACROSS THE GULF STATES. THE
PATTERN DEAMPLIFIES ON SUNDAY...WITH A FLAT RIDGE ACROSS THE
SOUTHERN TIER OF STATES...AND ZONAL FLOW ACROSS THE NORTHERN TIER.

HIGH PRESSURE WILL BUILD INTO OUR AREA FROM THE NW ON FRIDAY NIGHT
AND SATURDAY. MODEL TIME HEIGHTS SHOW LIMITED LOW LEVEL MOISTURE
LINGERING UNDER A MID LEVEL INVERSION...BUT WITHOUT FORCING OR
BUOYANCY TO SUPPORT CONVECTION.

MOISTURE WILL INCREASE OVER OUR AREA ON SATURDAY NIGHT AND SUNDAY ON
THE BACK SIDE OF THIS HIGH PRESSURE...ESPECIALLY OVER THE MOUNTAINS.
THE MID LEVEL CAP REMAINS...BUT IS WEAKER. SMALL POPS WILL MAINLY
FAVOR MOUNTAINOUS TERRAIN...WHERE AN UPSLOPE FLOW MAY ASSIST IN
OVERCOMING THE WEAK CAPPING INVERSION.

TEMPERATURES WILL RUN A FEW DEGREES BELOW NORMAL ON SATURDAY IN THE
WAKE OF A DEPARTING COLD FRONT AS COOL HIGH PRESSURE ARRIVES.
TEMPERATURES WILL MODERATE UPWARD TOWARD NORMAL VALUES ON SUNDAY AS
HEIGHTS RISE ALOFT AND SOUTHERLY LOW LEVEL FLOW SETS UP.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AT 230 PM EDT THURSDAY...AN UPPER TROUGH BEGINS TO AMPLIFY FROM THE
GREAT LAKES TO THE GULF STATES ON MONDAY. ON TUESDAY THIS TROUGH
REACHES THE CENTRAL AND SOUTHERN APPALACHIANS. ON WEDNESDAY THE
TROUGH REACHES THE EASTERN SEABOARD...AND ON THURSDAY IT MOVES OFF
THE EAST COAST...WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS.

ATLANTIC HIGH PRESSURE WILL EXTEND OVER THE CAROLINAS AND GA ON
MONDAY...WITH A LEE TROUGH EXPECTED EAST OF THE MOUNTAINS. THIS HIGH
PRESSURE WEAKENS ON TUESDAY WHILE A COLD FRONT APPROACHES FORM THE
NW. THE FRONT IS EXPECTED TO CROSS OUR AREA ON TUESDAY NIGHT...
STALLING JUST SOUTH OF OUR AREA ON WEDNESDAY AND THURSDAY.

CONVECTIVE CHANCES WILL IMPROVE AS THE FRONT APPROACHES AND HEIGHTS
FALL ALOFT. ACTIVITY WILL DECREASE BEHIND THE FRONT...BUT WITH THE
BOUNDARY AND ASSOCIATED MOISTURE REMAINING IN THE VICINITY...SOME
ACTIVITY CAN BE EXPECTED TO LINGER IN THE SOUTHERN PORTION OF THE
AREA ON WEDNESDAY AND THURSDAY. TEMPERATURES WILL EXHIBIT A REDUCED
DIURNAL TREND DUE TO CLOUDS AND MOISTURE...WITH HIGHS JUST BELOW
NORMAL...AND LOW A BIT ABOVE NORMAL.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
AT KCLT...CONVECTION FINALLY MOVING S AND E OF THE AIRFIELD ATTM.
EXPECT LIGHT N TO NW WIND AS THE WX MOVES OUT OF THE AREA. ANY LOW
VFR CIG SHOULD BE BRIEF WITH CLOUDS LIFTING THRU THE EVENING. EXPECT
THE NLY WIND TO CONTINUE THRU THE DAY FRI WITH SOME LOW END GUSTS
POSSIBLE WITH MIXING BY MID MORNING. SOME HIGH BASED CU MAY DEVELOP
DURING THE AFTERNOON.

ELSEWHERE...CONDITIONS ELSEWHERE WILL BE THE SAME AS AT KCLT. THE
EXCEPTION IS KAND WHERE STORMS ARE SLOWER MOVING S AND EAST...AND
KAVL WHERE SOME LOW CLOUDS MAY MOVE IN THIS EVENING THEN VALLEY FOG
DEVELOPS BY DAYBREAK. ANY RESTRICTIONS SHOULD QUICKLY DISSIPATE
AFTER SUNRISE.

OUTLOOK...HIGH PRESSURE WILL PRODUCE GENERALLY QUIET WEATHER AND VFR
CONDITIONS THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   73%     LOW   56%     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...JAT
NEAR TERM...MCAVOY/RWH
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...RWH