Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 301751
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
151 PM EDT MON MAR 30 2015

.SYNOPSIS...
HIGH PRESSURE WILL REBUILD OVER THE REGION TODAY AND LINGER THROUGH
MOST OF TUESDAY. ANOTHER WEAK COLD FRONT WILL MOVE OVER THE AREA
TOMORROW NIGHT WITH HIGH PRESSURE QUICKLY BUILDING AGAIN FOR
WEDNESDAY AND THURSDAY. YET ANOTHER COLD FRONT IS EXPECTED TO
APPROACH THE CAROLINAS BY LATE FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 145 PM...LATEST VIS SATELLITE IMAGES INDICATED THAT CLOUD
COVER ACROSS THE REGION HAS BECOME SKC TO FEW ACROSS THE REGION.
TEMPERATURES ARE FORECAST TO RISE ANOTHER 3-4 DEGREES THEN BEGIN TO
COOL HEADED INTO THE LATE AFTERNOON. I WILL UPDATE THE FORECAST TO
ADJUST SKY TIMING AND INDICATE LATE AFTERNOON WIND GUSTS.

AS OF 930 AM...THE BAND OF PREFRONTAL SHOWERS AND THUNDERSTORMS HAVE
EXITED THE CWA TO THE EAST...WITH ONLY UNION COUNTY UNDER LIGHT RA.
THE CWA SHOULD BECOME DRY OVER THE NEXT HOUR. I WILL UPDATE THE
FORECAST DECREASE POPS AND QPF ACROSS THE CWA. IN ADDITION...I WILL
INCREASE SKY COVER AND SLOW THE MORNING DIURNAL WARMING RATE. THIS
AFTERNOON...THE COLD FRONT WILL PUSH OVER THE PIEDMONT...RESULTING
IN LIGHT DOWNSLOPE FLOW. CLEARING SHOULD OCCUR THROUGH THE AFTERNOON
HOURS. HOWEVER...SLOW WARMING THIS MORNING WILL PLACE THE CURRENT
FORECAST OUT OF PACE FOR HIGH TEMPERATURES. THE UPDATE WILL ALSO
FEATURE HIGH TEMPERATES SEVERAL DEGREES COOLER...WITH AROUND 60
WITHIN THE MTN VALLEYS TO MID TO UPPER 60S EAST.

AS OF 630 AM...LARGE AREA OF RAIN...WITH EMBEDDED THUNDERSTORMS...
WAS MOVING VERY RAPIDLY ACROSS SRN NC/UPSTATE SC/NE GEORGIA...DRIVEN
EWD BY A STRONG LOW LEVEL JET. HAVE RAISED PRECIP PROB TO
CATEGORICAL MOST PLACES S OF I-40 BASED ON RADAR TREND. SOME PLACES
COULD PICK UP AN INCH OR SO OF PRECIP WHERE THE MODERATE RAIN IN THE
TRAILING STRATIFORM REGION LINGERS LONGEST. TEMPS WERE TWEAKED BASED
ON OBS. THE MODELS TAKE THE BAND OF PRECIP AHEAD OF THE FRONT
EASTWARD ACROSS THE FCST AREA FAIRLY RAPIDLY THIS MORNING...AS THE
SHORT WAVE ROTATES QUICKLY AROUND THE BOTTOM OF THE UPPER TROF. THIS
SHOULD DRIVE THE SURFACE FRONTAL ZONE EAST OF THE REGION BY MIDDAY.
COVERAGE SHOULD BE NOT AS GREAT ALONG/N OF I-40 WHERE DOWNSLOPE E OF
THE MTNS WILL BE UNFAVORABLE. PRECIP CHANCES RAMP DOWN QUICKLY BY
MIDDAY. TEMPS SHOULD REBOUND NICELY...ABOUT TEN DEGREES ABOVE
YESTERDAY...IN SPITE OF THE SFC BOUNDARY MOVING THRU...BECAUSE OF
THE W/NW DOWNSLOPE FLOW IN THE AFTERNOON.

TONIGHT SHOULD BE QUIET AS HIGH PRESSURE BUILDS BACK IN FROM THE NW.
MIN TEMPS WILL BE BELOW NORMAL AGAIN. THERE ARE SOME MINOR CONCERNS
FOR FROST/FREEZE OVER THE MTNS...BUT THE TEMPS BELOW 32F ARE MAINLY
CONFINED TO THE HIGHER ELEVATIONS...AND THE FROST POTENTIAL DOES NOT
APPEAR TO BE THAT GREAT BASED ON DEWPTS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM EDT MONDAY...THE SHORT TERM FCST PERIOD INITIALIZES
TUESDAY MORNING AMIDST CONTINUED NW FLOW PATTERN ALOFT...HIGHLIGHTED
BY A NORTHERN STREAM SHORTWAVE SLIDING THROUGH THE SOUTHERN GREAT
LAKES REGION.  WEAK SURFACE CYCLOGENESIS BENEATH WILL AID COLD FRONTAL
PROGRESSION ACROSS THE MIDWEST INTO THE OHIO VALLEY ON TUESDAY AHEAD
OF SPRAWLING HIGH PRESSURE.  MEANWHILE ACROSS THE SOUTHERN PLAINS
ANOTHER SURFACE WAVE WILL FORM IN THE LEE OF THE SOUTHERN ROCKIES
ALLOWING FOR DEVELOPMENT OF MODEST BAROCLINIC ZONE OVER THE
SOUTHEAST TUESDAY AFTERNOON INTO WEDNESDAY.  WARM FRONT LEADING THE
CHARGE NORTHWARD ON TUESDAY WILL ADVANCE INTO THE I20 CORRIDOR LATE
IN THE DAY WITH ACTIVATION LIKELY AS MORE UNSTABLE AIR ADVECTS
NORTHWARD.  AS THE ABOVE MENTIONED COLD FRONT CONTINUES TO SLIDE
SOUTH THROUGH THE TN VALLEY...EXPECTING CONVECTION ALONG THE FRONTAL
ZONE WHICH COULD PUSH INTO THE WESTERN NC MTNS LATE TUESDAY NIGHT.
MODELS CONTINUE TO HINT AT SOME RESIDUAL INSTABILITY AFTER SUNSET
AHEAD OF THE FRONT...HOWEVER DECREASING WITH HEATING LOSS...AND
DRIER AIR ADVECTION BEHIND THE FRONT AS IT BACK DOORS INTO THE
REGION.  THE FRONT WILL SLIDE SOUTH THROUGH THE REMAINDER OF THE
FCST AREA OVERNIGHT...AS HIGH PRESSURE SETS UP ALONG THE EASTERN
SEABOARD.  BRIEF HEIGHT RISES ALOFT COMBINED WITH RIDGING AT THE
SURFACE WILL KEEP THE WX DRY ON WEDNESDAY AHEAD OF RETURNING MOIST
SOUTHERLY UPGLIDE ATOP POSSIBLE INSITU CAD THURSDAY MORNING.

AS FOR THE FCST...POPS WILL SLOWLY INCREASE INTO TUESDAY EVENING
ACROSS THE NORTHEAST GA AND WESTERN NC MTNS TO ACCOUNT FOR WEAK
FRONTAL ZONE ASSOCIATED CONVECTION...WITH POPS REMOVED BY MID
MORNING WEDNESDAY AS THE COLD FRONT SLIDES THROUGH.  POPS WILL
REMAIN BELOW MENTIONABLE LEVELS THROUGH THE DAY WEDNESDAY BEFORE
INCREASING MID/LATE EVENING AS MODELS CONTINUE TO HINT AT WEAK
INSITU CAD REGIME ON THE WESTERN FLANK OF THE COASTAL SFC RIDGE.  GFS
ISENTROPIC CHARTS INDICATE IMPROVING UPGLIDE IN THE LOW
LEVELS...THUS CHANCE LEVEL POPS WERE FAVORED OVER THE WESTERN HALF
OF THE FCST AREA TAPERING TO SLIGHT CHANCE FURTHER EAST ON THE
FRINGE OF UPGLIDE MAXIMA.  TEMPERATURES THROUGH THE PERIOD WILL
REMAIN ABOVE NORMAL LEVELS DESPITE THE WEAK FROPA TUESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AT 230 PM EDT MONDAY...ON FRIDAY EVENING NEARLY ZONAL FLOW WILL BE
OVER THE SOUTHERN TIER OF STATES AS WEAK UPPER RIDGING WILL BE OFF
THE EAST COAST...AND LOW AMPLITUDE TROUGHING WILL EXTEND FROM THE
UPPER MIDWEST TO THE SW USA. THE UPPER TROUGH MOVES TO THE GREAT
LAKES AND CENTRAL MS RIVER VALLEY BY SATURDAY...BUT UPPER FLOW
REMAINS ALMOST ZONAL OVER THE SOUTHEAST. THE TROUGH AMPLIFIES
SLIGHTLY AS IT CROSSES THE SOUTHERN APPALACHIANS...THEN DEAMPLIFIES
AS IT MOVES OFF THE EAST COAST ON SUNDAY.  BY LATE SUNDAY THE MODELS
GO OUT OF PHASE OFF EACH COAST...RESULTING IN DIFFERENCES IN FLOW
OVER THE SE.

AT THE SURFACE...A COLD FRONT WILL APPROACH FROM THE NW ON THURSDAY
NIGHT AND FRIDAY...PRECEDED BY ROBUST GULF INFLOW INTO THE SOUTHERN
APPALACHIANS. THE FRONT CROSSES OUR AREA EARLY SATURDAY...FOLLOWED
BY DRY HIGH PRESSURE ON SUNDAY. BY MONDAY THE SURFACE HIGH MOVES OFF
THE EAST COAST...BUT HIGH PRESSURE REMAINS LODGED ALONG THE EASTERN
SEABOARD...WHILE GULF INFLOW SPREADS MOISTURE UP THE MS...TN AND OH
RIVER VALLEYS. THIS MOISTURE AND ASSOCIATED RAINFALL SPREADS EAST
ACROSS OUR AREA DURING THE DAY. TEMPERATURES WILL RUN ABOVE NORMAL
AHEAD OF THE FIRST FRONT...SLIGHTLY BELOW NORMAL BEHIND IT...THEN
RETURN TO ABOVE NORMAL AHEAD OF THE SECOND FRONT.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...AT 1730Z...THE KGSP RADAR APPEARED TO SHOW
THE WIND SHIFT ENTERING NORTHERN GREENVILLE/SPARTANBURG
COUNTIES...MOVING SOUTHEAST AROUND 10 KTS. IN THE WAKE OF THE
FRONT...KAVL WILL LIKELY MAINTAIN GUSTY NORTH WINDS THROUGH
SUNSET. TO THE EAST OF THE FRONT...TERMINALS ARE FORECAST TO SEE
WINDS VEER AND MARGINAL WIND GUSTS. TONIGHT...THE CENTER OF DRY
AND COOL HIGH PRESSURE WILL SETTLE NEARLY OVER THE WESTERN
CAROLINAS. WINDS WILL LIKELY RANGE FROM CALM TO 4 KTS BY LATE
TONIGHT. AFTER SUNRISE...THE CENTER OF HIGH PRESSURE WILL PUSH OFF
THE CAROLINA COAST AS ANOTHER COLD FRONT APPROACHES FROM THE WEST.
THIS PATTERN WILL SUPPORT STRENGTHENING SW WINDS THROUGH THE
MORNING HOURS...WITH GUST INTO THE TEENS DEVELOPING BY LATE
MORNING.

OUTLOOK...VFR THROUGH WEDNESDAY. AN APPROACHING WARM FRONT AND
RESULTANT MOISTURE RETURN WILL BRING BETTER CHANCES FOR
PRECIP/RESTRICTIONS ACROSS THE AREA LATER IN THE WEEK...PERHAPS
STARTING THURSDAY MORNING. EVENTUALLY...A SLOW MOVING COLD FRONT
WILL AFFECT THE AREA FRIDAY OR SATURDAY WITH MORE RESTRICTIONS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
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...JPT
NEAR TERM...NED/PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...NED



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