Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 260624
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
224 AM EDT THU MAR 26 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 TODAY/...
AS OF 220 AM...TCLT AND KGSP DETECTED SEVERAL PATCHES OF -RA/-DZ
ACROSS THE REGION...WITH THE HIGHEST REFLECTIVITY VALUES EAST OF
CLT. I WILL UPDATE THE FORECAST TO EDIT POP TRENDS AND VALUES.
OTHERWISE...THE CURRENT FORECAST APPEARS IN GOOD SHAPE.

EVENING UPDATE...POPS WERE BUMPED DOWN OVERNIGHT
BASED ON LATEST REG RADAR COMP AND CAMPOP OUTPUT. THE HIRES MODELS
ARE OVERDONE WITH PRECIP COVERAGE OVERNIGHT EXCEPT PERHAPS THE RA
WHICH WAS FOLLOWED MORE CLOSELY WITH THE TRENDS. QPF AMOUNTS WERE
ALSO ADJ DOWN AS FORCING WILL REMAIN WEAK AS WEDGE BREAKS DOWN AND
H85 FLOW VEERS THROUGH DAYBREAK. WIDESPREAD ADJS WERE MADE TO MIN
TEMPS AS WELL WITH SOME LOCALES ALREADY AT THEIR FCST/D MINS AND
OTHER AREAS A CAT OR SO ABOVE THE FCST CURVE.

AT 730 PM EDT...UPDATED THE POPS GRIDS WITH A LOWERING TREND MAINLY
FOR LATER THIS EVENING. HOURLY TEMPS 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 /TONIGHT 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 /07Z THURSDAY THROUGH MONDAY/...
AT KCLT...WEAK LLVL LIFT AND DEEP MOISTURE WILL SUPPORT RESTRICTIVE
CEILINGS THROUGH MID MORNING ACROSS THE TERMINAL. AT 6Z...TCLT AND
KGSP DETECTED SEVERAL PATCHES OF -RA/-DZ ACROSS THE REGION...WITH
THE HIGHEST REFLECTIVITY VALUES EAST OF CLT. MODEL SOUNDING AND
CLIMO INDICATE THAT IFR CEILINGS WILL LIKELY DEVELOP BY
9Z...POSSIBLY A LITTLE EARLIER. IFR CEILINGS AND ROUNDS OF
-RA/-DZ WILL CONTINUE UNTIL 14Z. A COLD FRONT IS EXPECTED TO SWEEP
EAST ACROSS THE CAROLINAS THIS EVENING. AS THE FRONT
APPROACHES...SOUTHWEST WINDS WILL STRENGTHEN TO AROUND 10 KTS...WITH
GUSTS NEAR 20 KTS BETWEEN 16Z-02Z. CLOUD BASES SHOULD LIFT TO 035-
080 KFT THIS AFTERNOON AND EARLY EVENING. THE POSITION OF THE COLD
FRONT IS FORECAST TO REACH THE I-85 CORRIDOR AROUND 6Z FRI. IT
APPEARS THAT SOUTHWEST WINDS WILL REMAIN THROUGH THE 6Z TAF
PERIOD...A PERIOD OF MVFR CEILINGS COULD DEVELOP ALONG AND AHEAD OF
THE COLD FRONT.

ELSEWHERE...TERMINAL CONDITIONS WILL LIKELY REMAIN SIMILAR TO KCLT.
KAND/KGSP/KGMU/KAVL RECEIVED SOME RAINFALL WED AFTERNOON/EVENING. IT
IS POSSIBLE THAT VIS MAY FALL ACROSS AREAS OF WET SOIL.
OTHERWISE...WEAK LLVL LIFT AND UPSLOPE FLOW WILL SUPPORT IFR
CEILINGS THROUGH MID MORNING. CLOUDS ARE FORECAST TO IMPROVE TO VFR
BY MID DAY...AS SOUTHWEST WINDS BECOME MARGINALLY GUSTY. A COLD FRONT
WILL PUSH ACROSS THE MTNS LATE THIS AFTERNOON AND EVENING. A FIELD
OF WEAK CAPE IS EXPECTED TO DEVELOP ALONG AND AHEAD OF THE
FRONT...POSSIBLY SUPPORTING TSRA. THE COVERAGE AND TIME WINDOW OF
THE TSRA APPEAR TOO LIMITED TO MENTION IN THE 6Z TAFS.

OUTLOOK...IMPROVING CONDITIONS ARE LIKELY ON FRIDAY IN THE WAKE OF A
COLD FRONT...BUT SCATTERED SHOWERS WILL CONTINUE TO PRODUCE SOME
RESTRICTIONS. HIGH PRESSURE WILL BUILD OVER THE REGION BEGINNING
FRIDAY NIGHT PRODUCING VFR CONDITIONS.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH  80%     HIGH  82%     HIGH  98%     HIGH  95%
KGSP       HIGH  87%     HIGH  91%     HIGH  98%     HIGH  88%
KAVL       HIGH  85%     MED   76%     HIGH 100%     HIGH  80%
KHKY       HIGH  96%     HIGH  89%     HIGH  98%     HIGH  83%
KGMU       HIGH  89%     HIGH  90%     HIGH  98%     HIGH  88%
KAND       HIGH  85%     HIGH  91%     HIGH  97%     HIGH  86%

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...NED
SHORT TERM...RWH
LONG TERM...JAT
AVIATION...NED
CLIMATE...



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