Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 252333
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
733 PM EDT WED MAR 25 2015

.SYNOPSIS...
SOUTHERLY FLOW WILL GRADUALLY INCREASE AHEAD OF AN APPROACHING COLD
FRONT TONIGHT THROUGH THURSDAY. THE COLD FRONT WILL CROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA THURSDAY NIGHT...MAINLY
DURING THE EVENING HOURS. A TRAILING UPPER LEVEL DISTURBANCE WILL
THEN CROSS THE AREA FRIDAY THROUGH FRIDAY NIGHT. DRY AND COOL HIGH
PRESSURE WILL SETTLE IN OVER THE WEEKEND. A LOW PRESSURE CLIPPER
SYSTEM AND ASSOCIATED COLD FRONT WILL PASS OVER THE REGION FROM THE
NORTHWEST AROUND THE START OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AT 730 PM EDT...UPDATED THE POPS GRIDS WITH A LOWERING TREND
MAINLY FOR LATER THIS EVENING. HOURLY TEMPS AND WERE ADJ UP IN THE
UPSTATE AND SRN NC PIEDMONT WITH THE LAST BIT OF DIFFERENTIAL
HEATING SHOWING UP. SKY COVER REMAINS TRICKY THIS EVENING AND
THROUGH THE OVERNIGHT ACROSS MOST OF THE HIGHER TERRAIN AND THE FAR
SRN ZONES...BUT FOR NOW HAVE MADE A GENERAL INCREASE IN COVERAGE
ACROSS THE SOUTH BASED ON CONTINUED LLVL MOISTURE FLUX.

AT 530 PM EDT...UPDATED THE GRIDS TO ACCOUNT FOR CHANGING CLOUD
COVER AND POCKETS OF DIFFERENTIAL HEATING. TRICKY SKY EVOLUTION WITH
DRIER AIR MIXING IN FROM THE SOUTH AND THIN WEAK BANDS OF -RA/DZ
PUSHING NORTH WITHIN SE/LY H85 FLOW. SFC WEDGE IS HOLDING STRONG FOR
NOW...SO WILL STAY MOSTLY CLOUDY MOST LOCALES NON/MTNS. THE MTN SKY
COVER WAS REDUCED SIGFNTLY WITH MODERATELY DEEP CU DIMINISHING WITH
LOSS OF HEATING.

AT 220 PM...HIGH PRESSURE REMAINS WEAKLY WEDGED ACROSS THE AREA WITH
THE PARENT HIGH WELL OFFSHORE. WEAK ISENTROPIC UPGLIDE OVER THE CAD
AREA CONTINUES TO PRODUCE A FEW SHOWERS. HOWEVER..THE LATE MARCH SUN
HAS ERODED THE CAD OVER THE LOWER PIEDMONT AREAS AND THE WESTERN
MOUNTAINS HAVE SEEN PARTIAL SUNSHINE ALL DAY. SOME IMPROVEMENT IN
THE LOW CLOUDINESS WILL CONTINUE ACROSS THE UPSTATE AND NE GA THIS
AFTERNOON AND RADAR INDICATES THAT PASSING SHOWERS WILL OCCUR SOME
AREAS.

FOR THE OVERNIGHT...CLOUDS WILL THICKEN AND LOWER AS THE BOUNDARY
LAYER COOLS. ALSO EXPECT THAT REAS OF LIGHT RAIN/DRIZZLE/FOG WILL
DEVELOP AS LOW LEVEL MOISTURE REMAINS ABUNDANT ALONG WITH WEAK
ISENTROPIC UPGLIDE. TEMPS WILL REMAIN MILD AND ABOVE CLIMO OVERNIGHT.

ON THU...THE ISENTROPIC UPGLIDE WILL BE CUT OFF IN THE MORNING AS
WINDS VEER TO THE SW AHEAD OF AN APPROACHIGN COLD FRONT. PARTIAL
CLEARING SHOULD OCCUR AND WITH THE INCREASING SUNSHINE MAX TEMPS
SHOULD REACH WELL INTO THE 70S EAST OF THE MOUNTAINS WITH 60S TO
AROUND 70 MOUNTAIN LOCATIONS. LOOKS LIKE THE FRONT WILL NOT REACH
THE WESTERN MOUNTAINS UNTIL AROUND 00Z SO SHOWER/THUNDERSTORM
CHANCES WILL BE ON THE LOW THROUGHOUT THE DAY WITH HIGHEST POPS
MOUNTAINS DURING THE LATE AFTERNOON.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 255 PM WEDNESDAY...GUIDANCE IN PRETTY GOOD AGREEMENT ON THE WX
PATTERN THRU THE SHORT RANGE. THE FIRST IN A SERIES OF SHORT WAVES
CROSSES THE AREA THU NITE IN THE SWLY FLOW ALOFT AHEAD OF A
DEEPENING TROF OVER THE MS RIVER VALLEY. THE TROF AXIS MOVES TO THE
WRN CWFA BORDER FRI AS A SHORT WAVE ROUNDS THE BASE OF THE TROF. THE
TROF AXIS MOVES INTO THE CWFA FRI NITE...THEN EAST OF THE AREA SAT
AS YET ANOTHER SHORT WAVE DIVES INTO THE AREA THRU THE TROF.

AT THE SFC...A COLD FRONT SLOWLY CROSSES THE AREA THU NITE AS WEAK
WAVES OF LOW PRESSURE FORM ALONG THE FRONT. MOST OF THE PRECIP WILL
BE BEHIND THE FRONT WITH SOME TSRA POSSIBLE...MAINLY OVER THE WRN
CWFA WHERE ANY WEAK INSTABILITY CAN COMBINE WITH THE FORCING TO
BREAK THE MID LEVEL CAP SEEN IN FCST SOUNDINGS. LOWS WILL BE 5 TO 10
DEGREES ABOVE NORMAL.

FRIDAY THRU FRIDAY NIGHT...ONE OF THE WAVES DEVELOPING ALONG THE
FRONT STRENGTHENS AS IT REACHES THE ATLANTIC COAST...HELPING KEEP
COPIOUS LOW LEVEL MOISTURE ACROSS THE AREA. THIS WILL COMBINE WITH
INSTABILITY DEVELOPING AS COLD MID LEVEL AIR MOVES OVERHEAD WITH THE
TROF TO PRODUCE THE CHC OF SHRA OUTSIDE OF THE MTNS. ALTHOUGH
GUIDANCE AGREES ON THIS SCENARIO...THEY DO NOT AGREE ON THE BEST
LOCATIONS AND TIMING FOR THE SHRA TO DEVELOP. THEREFORE...HAVE
LIMITED POP TO SLIGHT CHC FOR NOW. THE SHRA MOVE EAST ACROSS THE
AREA AND EXIT/DISSIPATE LATE FRI NITE. ACROSS THE MTNS HOWEVER...
GUIDANCE IS IN GOOD AGREEMENT ON ELEVATION DEPENDENT SNOW SHOWERS
FRI WITH SNOW LEVELS FALLING FRI NITE. THERE COULD BE A LIGHT
ACCUMULATION ACROSS THE USUAL HIGH ELEVATION AREAS BY THE TIME THE
SNOW SHOWERS END EARLY SAT. HIGHS FRI WILL BE NEARLY 10 DEGREES
BELOW NORMAL WITH LOWS FRI NITE 5 TO 10 DEGREES BELOW NORMAL.

SAT WILL BE DRY WITH CLEARING SKIES. HIGHS WILL BE 10 TO 15 DEGREES
BELOW NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 230 PM EDT WEDNESDAY...ON SATURDAY EVENING...A MEAN UPPER TROUGH
WILL BE OVER THE EASTERN HALF OF THE NATION...WITH AN UPPER RIDGE
OVER THE WESTERN HALF. THE PATTERN FLATTENS OUT BY WEDNESDAY...WITH
ZONAL UPPER FLOW OVER THE SOUTHERN TIER OF STATES.

AT THE SURFACE...DRY HIGH PRESSURE WILL BE CENTERED OVER THE CENTRAL
APPALACHIANS ON SUNDAY. THIS HIGH SETTLES SOUTH TO GA BY MONDAY. A
COLD FRONT EXTENDING FROM EASTERN CANADA TO THE MID MS RIVER VALLEY
AND S PLAINS ON MONDAY WILL DROP SE ACROSS THE CAROLINAS ON
TUESDAY...WHILE THE WESTERN PORTION MOVES N AS A WARM FRONT INTO THE
MID MS RIVER VALLEY. ON WEDNESDAY THE SURFACE RIDGE MOVES OFF THE
COAST...AND GULF INFLOW INCREASES INTO THE SOUTHERN APPALACHIANS.

PRECIPITATION CHANCES MONDAY WILL BE BEST IN THE MOUNTAINS AS THE
COLD FRONT APPROACHES FORM THE NW...AND WILL BE LOWER IN THE LEE LOW
LEVEL FLOW TAKES ON A WESTERLY DOWNSLOPE FLOW COMPONENT ON TUESDAY.
PRECIPITATION CHANCES WILL INCREASE AGAIN ON WEDNESDAY AHEAD OF
ANOTHER COLD FRONT CROSSING THE GREAT LAKES AND MID MS RIVER VALLEY.

TEMPERATURES WILL STAR OUT AROUND 10 DEGREES ABOVE NORMAL ON SUNDAY
IN A COLD AIR MASS....WARMING TO NEAR NORMAL MONDAY IN ADVANCE OF
THE NEXT FRONT...AND REMAINING THERE THROUGH WEDNESDAY IN DOWNSLOPE
WARMING BEHIND THE FRONT AND WARM ADVECTION IN ADVANCE OF THE NEXT
FRONT.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...LLVL CLOUDS IN THE MVFR RANGE WILL PERSIST THIS EVENING
WITH PERHAPS TEMPO VFR DRY AIR MIXING IN FROM THE SOUTH BEFORE
MIDNIGHT. THE SFC WEDGE WILL BEGIN TO BREAKDOWN THROUGH THE OVERNIGHT
WITH LLVL MOIST FLOW CONTINUING OFF THE ATL...THUS A LOWERING OF
CIGS INTO IFR/LIFR WILL DEVELOP AFT 06Z OR SO AND REMAIN THROUGH DAT
BREAK WITH A GRADUAL IMPROVEMENT INTO MVFR/VFR THROUGH NOON. SOME
LOWERING OF VSBY INTO MVFR IS ALSO POSSIBLE OVERNIGHT WITH WEAK
LINES OF -RA/DZ IN THE VICINITY BTW 03Z-09Z. WINDS WILL SHIFT AND
REMAIN SW/LY AFT 15Z WITH LOW END GUSTS POSSIBLE BY MID AFTERNOON IN
FAIRLY DEEP MIXING.

ELSEWHERE...SIMILAR TAF EVOLUTIONS TO THE KCLT TAF. EXPECT A
LOWERING OF CIGS WITH WEDGE BREAKDOWN AFTER MIDNIGHT. NOT MUCH OF A
VSBY THREAT...MAINLY MVFR OVERNIGHT...BUT THE UPSTATE COULD SEE IFR
WITH THE RECENT PRECIP. A GRADUAL IMPROVEMENT IN FLIGHT CONDS AFT 15Z
THROUGH NOON...WITH VFR EXPECTED IN THE AFTERNOON ALL SITES. WINDS
WILL SHIFT AND REMAIN SW/LY AFT 14Z/15Z WITH LOW/MODERATE GUSTS
POSSIBLE BY MID/AFTERNOON.

OUTLOOK...A COLD FRONT WILL CROSS THE AREA THU NIGHT ALONG WITH
RESTRICTIONS DUE TO SHOWERS AND THUNDERSTORMS. SOME IMPROVING
CONDITIONS ARE LIKELY BEHIND THE FRONT ON FRIDAY BUT SCATTERED
SHOWERS WILL CONTINUE TO PRODUCE SOME RESTRICTIONS. HIGH PRESSURE
WILL BUILD OVER THE REGION BEGINNING FRIDAY NIGHT PRODUCING VFR
CONDITIONS.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH  83%     MED   78%     HIGH  90%
KGSP       HIGH 100%     LOW   31%     HIGH 100%     HIGH  80%
KAVL       HIGH 100%     MED   78%     MED   62%     HIGH  90%
KHKY       HIGH 100%     LOW   38%     MED   76%     MED   70%
KGMU       HIGH 100%     LOW   23%     HIGH  93%     HIGH  80%
KAND       HIGH 100%     LOW   31%     HIGH  85%     HIGH  80%

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

&&

.CLIMATE...
RECORD MINIMUM TEMPERATURES FOR MARCH 28TH...

GSP  26  1982
CLT  25  1982
AVL  11  1887

RECORD MINIMUM TEMPERATURES FOR MARCH 29TH...

GSP  26  1899
CLT  26  2013
AVL  19  1982

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...LG/SBK
SHORT TERM...RWH
LONG TERM...JAT
AVIATION...SBK
CLIMATE...RWH



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