Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 240749
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
249 AM EST WED DEC 24 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS OUR AREA TODAY. HIGH PRESSURE WILL ARRIVE ON
THURSDAY AND LINGER INTO SATURDAY. A PAIR OF COLD FRONTS WILL
APPROACH THE AREA ON SUNDAY...CROSSING THE AREA MONDAY. GUSTY WINDS
WILL FOLLOW THE FRONT ON TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 AM EST...THE WESTERN TIER OF THE DENSE FOG ADVISORY HAS
BEEN CANCELLED WHERE MIXING FROM HEAVIER SHOWERS HAS OCCURRED. THE
ERN TIER OF THE DFA WILL CONTINUE FOR AT LEAST A COUPLE MORE
HOURS...MAINLY EAST OF INTERSTATE 77 WHERE 1/4SM VSBY STILL LOOKS
FAIRLY SOLID.

OTHERWISE...THE DEEPENING CENTRAL CONUS TROUGH STRETCHES FROM ERN IA
TO E TX EARLY THIS MORNING. THE LATEST SFC ANALYSIS SHOWS THE CAD
REGION OVERHEAD CONTINUING TO BECOME SHALLOWER AND PINCHED FROM THE
MIDLANDS...BUT WITH A NARROW NOSE OF HIGH PRES HOLDING ON WITH SFC
TEMPS IN THE 40S. A FEW LIGHTNING STRIKES CONTINUE TO SHOW UP FROM
TIME TO TIME IN THE HEART OF THE WARM CONVEYOR BELT PRECIP CROSSING
THE AREA EARLY THIS MORNING...BUT THE WEDGE LAYER STABILITY WILL
REMAIN TOO HOSTILE FOR ANY CONVECTIVE GUSTS TO REACH THE SURFACE.
THE HEAVIER RAIN BANDS ARE MOVING SUFFICIENTLY THAT A FLASH FLOOD
WATCH DOES NOT APPEAR TO BE NEEDED.

MEANWHILE...SFC LOW PRESSURE RIDING NORTHWARD ALONG THE COLD FRONT
NEAR THE MS/AL BORDER WILL SLOW THE BOUNDARY A BIT TODAY. EXPECT
COLD FROPA FROM THE WEST MAINLY IN THE 18Z TO 00Z TIME FRAME. THIS
WILL ALLOW SOME CAD EROSION FROM THE SE THROUGH LATE MORNING...WITH
SLIGHT SFC BASED INSTABILITY LIKELY GETTING UNCOVERED IN THE LOWER
PIEDMONT BY 18Z. IT STILL APPEARS THAT THE BEST SHEAR/INSTABILITY
WILL NOT HAVE STRONG OVERLAP...BUT ANY PRE/FRONTAL LINE SEGMENTS
WILL NEED TO BE WATCHED VERY CAREFULLY THROUGH THE DAY...ESPECIALLY
IN THE ERN PIEDMONT.

TEMPERATURE PROFILES WILL CRASH ACROSS THE HIGHER TERRAIN FROM THE
WEST AFTER 00Z POST FROPA. LOW LEVEL FLOW WILL HAVE A LESS THAN
FAVORABLE WESTERLY COMPONENT DURING THE UPSLOPE MOISTURE PERIOD
TONIGHT...WHICH WILL LIMIT SNOWFALL POTENTIAL IN THE COLD AIR.
HOWEVER...SOME MEASURE OF DEEP LAYER Q VECTOR CONVERGENCE WILL CROSS
THE MTNS WITH THE LIFTING TROUGH 06Z TO 12Z TONIGHT WHICH WILL GIVEN
WRN MTN POPS A SLIGHT BOOST. EXPECT A SUB ADVISORY EVENT FOR ANY
SNOWFALL ACCUMS AT THE HIGHER ELEVATIONS/TN BORDER AREA OVERNIGHT.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AT 230 AM EST WEDNESDAY...ON THURSDAY MORNING A WEAKENING UPPER
TROUGH WILL BE OVER THE EASTERN SEABOARD....WITH A WEAK RIDGE
UPSTREAM OVER THE EASTERN PLAINS...AND ANOTHER TROUGH OVER THE
ROCKIES. AN UPPER LOW CLOSES OFF AS IT DIVES INTO THE ROCKY MOUNTAIN
TROUGH ON FRIDAY...WHILE THE UPPER RIDGE DOWNSTREAM AMPLIFIES OVER
THE SOUTHERN APPALACHIANS AND GREAT LAKES.

AT THE SURFACE...THURSDAY MORNING WILL FEATURE MOIST WESTERLY FLOW
INTO THE NC MOUNTAINS BEHIND A DEPARTING COLD FRONT. WHILE THE
ORTHOGONAL COMPONENT INTO THE MOUNTAINS IS NOT IDEAL...SOME SNOW
SHOWERS MAY BE ONGOING IN THE MOUNTAINS BORDERING TN. AS A SURFACE
HIGH MOVES ACROSS THE GULF STATES DURING THE DAY...MOISTURE A COLD
ADVECTION DEPART...ENDING MOUNTAIN PRECIPITATION. THE DRY HIGH
PRESSURE WILL MOVE ACROSS GA AND THE CAROLINAS ON THURSDAY NIGHT AND
FRIDAY. LATE FRIDAY NIGHT...GULF MOISTURE WILL START TO REACH OUR
AREA IN SOUTHERLY FLOW BETWEEN THE ATLANTIC HIGH AND AND APPROACHING
COLD FRONT. TEMPERATURES WILL RUN A FEW DEGREES ABOVE NORMAL AS
HEIGHTS RISE ALOFT.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AT 230 AM EST WEDNESDAY...ON SATURDAY MORNING AND UPPER RIDGE AXIS
WILL BE OFF THE EAST COAST...WHILE AND UPPER TROUGH WILL EXTEND FROM
THE NORTHERN PLAINS TO THE SOUTHERN ROCKIES. BY SUNDAY MORNING THE
RIDGE MOVES FARTHER OFF THE EAST COAST...AND THE TROUGH MOVES INTO
THE PLAINS. THE PATTERN PROGRESSES VERY LITTLE INTO MONDAY...BUT BY
TUESDAY THE TROUGH AXIS ENTERS THE MS RIVER VALLEY.

SATURDAY MORNING STARTS OUT WITH SURFACE HIGH PRESSURE CENTERED NEAR
THE NC OUTER BANKS. THIS HIGH EXTENDS ACROSS THE WESTERN CAROLINAS
AND N GA...WHILE A COLD FRONT ENTERS THE MID AND LOWER MS RIVER
VALLEY...PRECEDED BY MOIST GULF INFLOW. THIS GULF INFLOW STARTS TO
WEAKENS ON SUNDAY AS THE FRONT SLOWLY CROSSES THE GULF STATE...AND
BECOMES QUITE LIMITED AS THE FRONT CROSSES GA AND THE CAROLINAS
SUNDAY NIGHT AND EARLY MONDAY. A SECONDARY FRONT CROSSES THE AREA
FROM THE NW LATE ON MONDAY...WITH COLD MOIST UPSLOPE FLOW IN ITS
WAKE SUPPORTING SNOW IN THE NC MOUNTAINS BORDERING TN INTO TUESDAY.
TEMPERATURES WILL RUN ABOVE NORMAL AHEAD OF THE PAIR OF FRONTS...AND
BELOW NORMAL BEHIND THEM.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...VLIFR TO LIFR RESTRICTIONS WILL PERSIST THROUGH MUCH OF
THE EARLY MORNING HOURS UNTIL MODERATE SHOWERS ARRIVE FROM THE WEST
TO PROVIDE SOME BRIEF MIXING BY 09Z TO 10Z...AND THEN CAD EROSION
OCCURS FROM THE SE 13Z TO 15Z. A FEW LIGHTNING STRIKES IN THE BETTER
SHOWERS THIS MORNING CANNOT BE RULED OUT GIVEN SOME ELEVATED
INSTABILITY OVER THE CAD LAYER. HOWEVER...THE BETTER TSTM CHANCES
WILL BE WITH ANY PRE/FRONTAL CONVECTION 16Z TO 20Z IN THE DEVELOPING
WARM SECTOR. CIGS WILL REMAIN LIFR THROUGHOUT...WITH HEFTY LLWS JUST
OFF THE DECK AS THE WEDGE CONTINUES TO SHALLOW. EXPECT ENE FLOW
EARLY BECOMING SE BY LATE MORNING AND THEN SOUTHERLY AND GUSTY AHEAD
OF THE COLD FRONT THIS AFTERNOON. RESTRICTIONS WILL LIFT WITH FROPA
THIS EVENING.

ELSEWHERE...CONDITIONS MAY BE QUITE VARIABLE UNDER THE MODERATE TO
HEAVY RAIN SHOWERS CROSSING THE REGION IN THE DEEP WARM CONVEYOR
BELT MOISTURE. EXPECT LIFR CIGS TO CONTINUE ON AVERAGE...WITH WIDELY
RANGING VSBY. STRAY LIGHTNING EMBEDDED IN THE LARGER RAIN SHIELD
WILL BE POSSIBLE THROUGHOUT THE MORNING...WITH BETTER TSTM PROBS AT
THE SC SITES JUST AHEAD OF THE COLD FRONT 15Z TO 18Z. EXPECT
CONTINUED NE TO ENE FLOW EARLY...BECOMING SE AND THEN SRLY BY AFTN.
RESTRICTIONS WILL LIFT RAPIDLY WITH FROPA FROM WEST TO EAST FROM
LATE AFTN THROUGH EARLY EVENING. WILL FEATURE VFR CIGS THROUGHOUT
TOWARD THE END OF THE PERIOD...BUT UPSLOPE MOISTURE COULD PUSH
LINGERING MVFR CIGS BACK INTO THE KAVL VICINITY.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD BACK INTO THE REGION THU
THROUGH FRI. ANOTHER COLD FRONT WITH MORE LIMITED MOISTURE WILL
ARRIVE FROM THE NW OVER THE WEEKEND.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH  88%     HIGH  81%     MED   74%     HIGH  83%
KGSP       HIGH  85%     HIGH  84%     MED   71%     HIGH 100%
KAVL       MED   75%     MED   75%     HIGH  93%     HIGH 100%
KHKY       MED   74%     MED   76%     MED   71%     HIGH  86%
KGMU       MED   79%     HIGH  82%     MED   68%     HIGH 100%
KAND       HIGH  87%     HIGH  84%     MED   79%     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...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ037-057-
     071-072-082.
SC...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ009-014.

&&

$$
SYNOPSIS...JAT
NEAR TERM...HG
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...HG



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