504 
FXUS62 KGSP 280605
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 AM EDT FRI MAR 28 2014

.SYNOPSIS...
A MOIST FRONTAL SYSTEM WILL AFFECT THE AREA FRIDAY THROUGH
SATURDAY. STRONG UPPER LEVEL RIDGING WILL BUILD IN DRY AND WARM
HIGH PRESSURE SUNDAY...WHICH WILL REMAIN ACROSS THE REGION INTO
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
115 AM UPDATE...PCPN NOW ADVANCING THRU THE UPPER TENN VALLEY IN 
WEAK AND ELEVATED WARM ADVECTION UNDER CYCLONIC FLOW ALOFT. THIS 
ACTIVITY WAS SUGGESTED BY SOME SHORT TERM GUIDANCE TO WEAKEN AS IT 
APPROACHED THE MTNS...WITH THE BETTER UPPER FORCING RIDING UP TOWARD 
WEST VIRGINIA. THIS APPEARS TO BE THE CASE. NONETHELESS MOIST 
UPGLIDE SCHEME STRENGTHENS TOWARD DAWN ACRS THE BLUE RIDGE. WHILE I 
INITIALLY BRING IN SCHC POPS TO ACCOUNT FOR ANY LIGHT PCPN FROM THE 
EXISTING SHIELD...POPS RAMP UP MORE AGGRESSIVELY TOWARD 12Z.

AT 1000 PM EDT THURSDAY...AN UPPER TROUGH AXIS WAS OVER THE WESTERN 
USA...WHILE AN UPPER RIDGE WAS ALONG THE EAST COAST. A SHORTWAVE WAS 
MOVING THROUGH THE TROUGH AXIS OVER THE MID MS RIVER VALLEY. THIS 
SHORTWAVE IS EXPECTED TO REACH THE LOWER GREAT LAKES BY DAYBREAK.
A COLD FRONT NOW LEAVING THE EASTERN PLAINS IS EXPECTED TO REACH THE 
OH RIVER VALLEY BY DAWN.

SATELLITE IMAGERY SHOWS LIMITED CLOUD COVER OVER THE WESTERN 
CAROLINAS AND NE GA...BUT CIRRUS ASSOCIATED WITH UPSTREAM CONVECTION 
WAS ENCROACHING FROM THE WEST. MODEL TIME HEIGHTS SHOW LOW LEVEL 
MOISTURE ARRIVING STARTING LATE THIS EVENING ON A SOUTHERLY FLOW. 
THIS FLOW WILL HAVE AND UPSLOPE COMPONENT INTO THE SOUTH FACING BLUE 
RIDGE ESCARPMENT... AND AN ISENTROPIC UPGLIDE COMPONENT OVER THE 
LINGERING EAST COAST SURFACE RIDGE. PRECIPITATION ASSOCIATED WITH 
THIS LIFT IS EXPECTED TO REACH THE AREA BEFORE DAWN. THE MODELS 
SUPPORT FAIRLY STRONG WINDS AT HIGH MOUNTAIN ELEVATIONS 
OVERNIGHT...PERHAPS REACHING ADVISORY CRITERIA ON THE VERY HIGHEST 
PEAKS IN WESTERN NC. LOWS WILL RANGE FROM THE MID AND UPPER 30S IN 
THE HIGH ELEVATIONS TO THE 40S ACROSS THE FOOTHILLS AND PIEDMONT.

PRECIPITATION WILL SPREAD QUICKLY TO THE EASTERN ZONES DURING THE 
MORNING AND EARLY AFTERNOON. BEFORE THE END OF THE DAY... WESTERN 
AND SOUTHWESTERN LOCATIONS SHOULD HAVE BETWEEN ONE HALF INCH TO AN 
INCH OF RAIN. PRECIPITATION TYPE WILL NOT BE A PROBLEM... EVEN IN 
THE MOUNTAINS WHERE SIGNIFICANT WARM AIR ADVECTION IS ALREADY 
UNDERWAY. THE TEMPERATURE RISE WILL BE TEMPERED BY THE CLOUD COVER 
AND PRECIPITATION ON FRIDAY WITH HIGHS IN THE MID AND UPPER 50S WITH 
60S ACROSS THE SOUTHERN AND EASTERN ZONES.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 200 PM THURSDAY...MAIN FOCUS FOR THE SHORT TERM WILL BE THE 
COLD FRONTAL PASSAGE DURING SATURDAY. AT THE ONSET OF THE PERIOD FRI 
NIGHT...WIDESPREAD RAIN SHOWERS SHOULD BE ONGOING WITH A MOIST GULF 
FLOW BEING LIFTED BY WEAK ISENTROPIC UPGLIDE AND THE HIGHER TERRAIN. 
WITH UPPER SUPPORT LACKING FRI NIGHT...DO NOT BELIEVE THAT QPF WILL BE
EXCESSIVE. ON SAT...12Z MODEL SUITE IN FAIRLY GOOD AGREEMENT THAT 
LOW PRESSURE WILL MOVE THROUGH THE OHIO VALLEY WITH A TRAILING COLD 
FRONT MOVING ACROSS THE AREA FROM WEST TO EAST. THE FRONT SHOULD 
MOVE EAST OF THE I-77 CORRIDOR IN THE 20Z-23Z TIMEFRAME. 
HENCE...WILL CONTINUE WITH IDEA OF NUMEROUS SHOWERS AND EVEN 
SCATTERED THUNDERSTORMS. IT APPEARS THAT CLOUDINESS AHEAD OF THE 
FRONT WILL LIMIT THE AMOUNT  OF CAPE TO ABOUT 400-600J.  BULK SHEAR 
IS FORECAST TO INCREASE DURING SAT...BUT UPPER WINDS ALSO BECOME 
MORE UNIDIRECTIONAL AS THE DAY PROGRESSES SO SEVERE THREAT DOES NOT 
LOOK ALL THAT GREAT. SPC HAS INDICATED THE SEVERE THREAT SHOULD BE 
PRIMARILY EAST AND SOUTH OF OUR AREA WHICH LOOKS REASONABLE. SHOWERS 
AND STORMS WILL END QUICKLY IN THE I-77 CORRIDOR SAT EVENING AS 
FRONT MOVES TO THE EAST. HOWEVER...THERE MAY BE A BRIEF NW FLOW SNOW 
EVENT IN THE MOUNTAINS SAT NIGHT AS TEMPS DROP AND WINDS BECOME 
FAVORABLE. PLUS...THE NORTHERN MOUNTAINS MAY BE BRUSHED BY THE UPPER 
LOW'S DEFORMATION ZONE. THEREFORE...HAVE INDICATED 
SHOWERS...CHANGING TO SNOW SHOWERS THERE RIGHT NOW ANY SNOW ACCUMS 
SHOULD BE LESS THAN 1 INCH. ALSO...WINDS WILL BECOME GUSTY SAT NIGHT 
INTO SUN AS SUBSIDENCE MIXES DOWN HIGHER SPEEDS ALOFT. TEMPS WILL BE 
ABOVE AVERAGE THROUGH SAT AND THEN COOL TO NEAR NORMAL VALUES ON 
SUN.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM EDT THURSDAY...NOT TOO MUCH CONTROVERSIAL EXPECTED 
THROUGH THE MEDIUM RANGE. WEATHER SHOULD BE QUIET SUNDAY NIGHT AND 
MONDAY AS AN UPPER RIDGE BUILDS IN FROM THE WEST...SUPPORTING DRY 
HIGH PRESSURE THAT MOVES IN OVER THE SOUTHEAST. MIGHT BE SOME 
CONCERN FOR FROST EAST OF THE MTNS SUNDAY NIGHT WITH CLEARING SKY 
AND LIGHT WIND ALLOWING TEMPS TO DROP INTO THE MID/UPPER 30S. HIGH 
TEMPS MONDAY WILL REBOUND BY AS MUCH AS TWO CATEGORIES COMPARED TO 
SUNDAY...SO ANOTHER WARM EARLY SPRING DAY IS EXPECTED. THE MODELS 
INDICATE THE PASSAGE OF A SHORT WAVE ON TUESDAY MORNING BUT THE 
OVERALL UPPER RIDGE AXIS REMAINS ALONG THE EAST COAST. THIS WAVE 
WILL HAVE VERY LITTLE MOISTURE TO WORK WITH...SO NOT MUCH MORE THAN 
A SLIGHT CHANCE OF SHOWERS OVER THE HIGHER TERRAIN IS EXPECTED. THE 
UPPER RIDGE AXIS MIGRATES SLOWLY OFF THE EAST COAST DURING THE 
MIDDLE OF THE WEEK WHICH WILL PUSH THE SURFACE HIGH OUT OVER THE 
ATLANTIC. AS A RESULT...SOME RETURN FLOW OF MOISTURE FROM THE GULF 
SHOULD STRENGTHEN AHEAD OF THE NEXT SHORT WAVE...WHICH THE MODELS 
SHOW MOVING IN FROM THE WEST ON THURSDAY AFTERNOON. THIS WAVE WILL 
HAVE MUCH MORE MOISTURE TO WORK WITH. ALTHOUGH THE SURFACE FRONT 
WILL REMAIN WELL TO THE NORTHWEST...THERE WILL BE SOME UPPER SUPPORT 
FOR SHOWER DEVELOPMENT TO GO ALONG WITH SOME INSTABILITY. PRECIP 
CHANCES RAMP UP TO THE CHANCE RANGE FROM THE WEST THROUGH THURSDAY 
AFTERNOON...WITH PERHAPS SOME THUNDERSTORMS E OF THE MTNS. TEMPS 
WILL BE ABOVE NORMAL.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT...BKN CIRRUS WILL BE SEEN UNTIL LOW VFR STRATOCU MOVE IN 
EARLY THIS AM...THE LATTER CLOUDS MAINLY COMING FROM DECAYING PCPN 
SHIELD COMING OUT OF THE TENN VALLEY. MEANWHILE LLVLS MOISTEN ON 
STRENGTHENING SOUTHERLY WINDS AND UPGLIDE. THERE REMAINS SOME THREAT 
FOR AN IFR STRATUS DECK TO DEVELOP NEAR DAYBREAK...BUT THIS IS NOT 
WELL AGREED UPON BY GUIDANCE. MOISTURE PROFILE HOWEVER SUPPORTS IT. 
SHOWERS WILL PREVAIL FROM MID MORNING ONWARD...BRINGING CIGS DOWN TO 
MVFR. THERE MAY BE SOMEWHAT OF A BREAK DURING THE AFTN ALLOWING SOME 
IMPROVEMENT IN FLT CAT...BUT AFTER SUNSET CONDITIONS WILL AGAIN 
WORSEN WITH MOIST FRONTAL BOUNDARY STILL NEARBY. WINDS WILL CONTINUE 
FROM THE S BUT STRONG 850MB JET MAY CAUSE LLWS ISSUES IN THE AREA.

ELSEWHERE...GENERALLY VFR THROUGH THE EARLY AM THOUGH CIGS WILL 
GRADUALLY LOWER TO MVFR THRU THE MORNING...OCCURRING BY AROUND 15Z 
IF NOT SOONER AS MOISTURE TRANSPORT AND PRECIP COVERAGE MAXIMIZES. 
SOME IFR POSSIBLE AT TIMES DURING THE HEAVIEST PRECIP. A LULL MAY 
COME DURING THE AFTN...PERHAPS ALLOWING BETTER FLT CATS FOR A 
TIME...BUT PRECIP WILL AGAIN INCREASE IN COVERAGE THIS EVENING AND 
CIGS/VSBY AGAIN LOWER. WINDS WILL CONTINUE SOUTHERLY BUT LLWS IS 
LIKELY TO BE PRESENT AT LEAST SPORADICALLY THRU THE MORNING.

OUTLOOK...SHOWERS AND POSSIBLY THUNDERSTORMS LATE FRIDAY NIGHT AND 
SATURDAY. VFR BUT WINDY ON SUNDAY. VFR WEATHER MONDAY. RESTRICTIONS 
IN SHOWERS POSSIBLE WHEN A COLD FRONT APPROACHES TUESDAY. VFR 
WEDNESDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z 
KCLT       HIGH  99%     HIGH  83%     HIGH  93%     HIGH  95%     
KGSP       MED   67%     HIGH  83%     MED   72%     HIGH  91%     
KAVL       HIGH  84%     MED   74%     HIGH  95%     HIGH 100%     
KHKY       HIGH  86%     HIGH  96%     HIGH  98%     HIGH 100%     
KGMU       MED   65%     HIGH  80%     MED   72%     HIGH  91%     
KAND       HIGH  90%     MED   62%     HIGH  88%     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...SBK
NEAR TERM...JAT/LGL/WIMBERLEY
SHORT TERM...LG
LONG TERM...PM
AVIATION...WIMBERLEY