Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 280840
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
340 AM EST SUN DEC 28 2014

.SYNOPSIS...
A COLD FRONT WILL SLOWLY CROSS OUR REGION THROUGH MONDAY...THOUGH
SOME MOISTURE WILL LINGER UNTIL TUESDAY. DRIER AND COOLER HIGH
PRESSURE WILL MOVE ACROSS THE AREA WEDNESDAY AND THURSDAY. ANOTHER
LOW PRESSURE SYSTEM THEN SHOULD BEGIN TO TAKE SHAPE AT THE END OF
THE WEEK...BRINGING PRECIPITATION BACK TO THE AREA BY FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AREA OF MODERATE RAIN IS FINALLY PUSHING ACROSS THE UPPER SAVANNAH
RIVER VALLEY THIS MORNING. IN GENERAL...THIS IS FARTHER SOUTH THAN
WHAT THE MODELS HAVE RECENTLY BEEN DEPICTING...AND THE HIGHEST QPF
FOR THIS MORNING HAS BEEN ADJUSTED TO THE UPSTATE AND NORTHEAST
GA...WHERE RAINFALL AMOUNTS THIS MORNING SHOULD RANGE FROM ONE
QUARTER TO ONE HALF INCH...WITH LOCALLY HIGHER AMOUNTS. THE PRECIP
SHIELD IS EXPECTED TO SHIFT NORTHWARD WITH TIME...AS THE BROAD BAND
OF ISENTROPIC LIFT TRANSLATES NORTHEAST TOWARD THE MID-ATLANTIC.
THEREFORE...THE MOUNTAINS AND FOOTHILLS OF WESTERN NC MAY YET SEE UP
TO A HALF INCH OF RAINFALL THIS MORNING...WITH LIGHTER AMOUNTS
TOWARD THE I-77 CORRIDOR.

AS UPGLIDE SHUTS OFF AND MID-LEVELS DRY OUT THIS AFTERNOON...PRECIP
SHOULD COME TO AN END...ALTHOUGH THE LOW LEVELS WILL REMAIN VERY
MOIST AND THERE MAY BE PATCHES OF DRIZZLE OR LIGHT RAIN LINGERING.
POPS WILL THEREFORE BE KEPT IN THE TOKEN CHANCE RANGE IN MOST AREAS
THROUGH THE AFTERNOON. WITH PRECIP FALLING INTO A DRY AIR MASS THIS
MORNING...FOLLOWED BY ABUNDANT LOW CLOUD COVER THROUGH THE
AFTERNOON...A WEAK IN-SITU CAD EVENT MAY RESULT...AND MAX TEMPS ARE
EXPECTED TO END UP BEING RATHER CLOSE TO CLIMO...DESPITE HIGH
THICKNESS VALUES FOR THE TIME OF YEAR.

A SHORT WAVE TROUGH EJECTING FROM TEXAS/THE LOWER MISS VALLEY
TONIGHT WILL DAMPEN AS IT ENCOUNTERS THE CONFLUENT UPPER FLOW ACROSS
THE EASTERN CONUS. NEVERTHELESS...A CONSENSUS OF MODEL GUIDANCE
DEPICTS WEAK CYCLOGENESIS OCCURRING ALONG A BAROCLINIC ZONE ACROSS
GEORGIA AND THE CAROLINAS...SUPPORTING ANOTHER ROUND OF RAINFALL
LATE TONIGHT INTO EARLY MONDAY...AND WARRANTING CATEGORICAL POPS IN
ALL AREAS ONCE AGAIN. ANOTHER ROUND OF .25-.50 INCH QPF APPEARS
LIKELY IN MOST AREAS.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM SUNDAY...PESKY FRONTAL ZONE FINALLY DOES LOOK TO BE
FORCED SOUTH AND EAST OF THE CWFA MONDAY AS A CANADIAN AIRMASS
EXPANDS OVER MOST OF THE ERN CONUS. COOLER AND DRIER AIR DO START TO
FILTER IN BY MONDAY NIGHT...BUT SOME LLVL MOISTURE DOES LINGER INTO
TUE. THE SOUTHEAST REMAINS UNDER BROADLY CYCLONIC FLOW THROUGH THAT
TIME...WITH AN EMBEDDED SHORTWAVE PROGGED TO MOVE FROM THE MID
MISSISSIPPI VALLEY TO THE DELMARVA BY TUE NIGHT. A WEAK BOUNDARY
ASSOCIATED WITH THIS WAVE WILL ENHANCE COLD ADVECTION AND LLVL LIFT
MON NIGHT/EARLY TUE...IN TIME TO ENCOUNTER THE MOISTURE. THUS POPS
EXHIBIT A SECONDARY PEAK TUE MRNG. AS WINDS VEER TO NW AROUND THAT
TIME...SOME UPSLOPE ENHANCEMENT IS ALSO EXPECTED WITH POPS TAKING A
LITTLE LONGER TO TAPER OFF TUE NEAR THE TENN BORDER. TEMPS ARE
EXPECTED TO REMAIN ABOVE CLIMO THROUGH TUE MRNG. PROFILES INDICATE AN
ACCORDINGLY WARM COLUMN...AND THE MOISTURE WILL BE CONCENTRATED IN
THE LOW TO MID LEVELS. ICE NUCLEATION AND SNOW PRODUCTION ARE
UNLIKELY...SO WITH TEMPS REMAINING ABOVE FREEZING THROUGHOUT THE CWFA
MON NIGHT NO MENTION OF WINTRY PRECIP HAS BEEN MADE.

IN THE WAKE OF THE BOUNDARY DEEPER DRYING BEGINS LATER TUE AND
CONTINUES THROUGH MID-WEEK...WITH SKIES TRENDING CLEARER. MAX TEMPS
WILL RETURN TO AROUND CLIMO TUE FOLLOWED BY SIMILARLY NORMAL TEMPS
FOR WED MRNG. DESPITE THE COLD ADVECTION...NOTABLY GUSTY WINDS ARE
NOT EXPECTED WITH THE LEADING EDGE OF THE AIRMASS HAVING ALREADY
PUSHED THROUGH.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 245 AM SUNDAY...REMARKABLY STRONG SFC HIGH PRESSURE OVER THE
CENTRAL PLAINS GETS SHUNTED SWD AS NRN STREAM SHORTWAVE DIVES INTO
THE MIDWEST AND PATTERN BEGINS TO REAMPLIFY OVER THE EAST. DRY AND
SEASONABLY COOL WEATHER WILL CONTINUE FOR OUR AREA WED-THU WITH TEMPS
NEAR CLIMO. THE SFC HIGH MOVES OVER THE SOUTHEAST BY THU NIGHT
INITIATING RETURN FLOW INTO THE WRN GULF STATES AS THE CUTOFF LOW
OVER THE DESERT SOUTHWEST PICKS UP SPEED. EVENTUALLY THAT WILL TRACK
ACRS THE MIDDLE OR LOWER MISSISSIPPI VALLEY...SPINNING UP A NEW
SYSTEM.  AGREEMENT BETWEEN THE 28/00Z RUNS OF THE GFS AND EC IS
GENERALLY GOOD...NOW ONLY SHOWING MINOR DIFFERENCES IN THE SFC LOW
TRACK. REGARDLESS OF THE PRECISE TRACK PRECIP CHANCES BEGIN TO
INCREASE THU NIGHT BEFORE PEAKING SATURDAY. MODELS HINT AT SOME PTYPE
CONCERNS EARLY IN THE EVENT WITH A POSSIBLE IN-SITU CAD EVENT
DEVELOPING...BUT THE BULK OF THE PRECIP SHOULD BE RAIN WITH TEMPS
TRENDING ABOVE NORMAL BEYOND FRIDAY.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
AT KCLT...THE OVERNIGHT/EARLY MORNING HOURS WILL SEE LOWERING
CIGS...WITH LOW VFR CONDITIONS EXPECTED BY DAYBREAK...AND INCREASING
CHANCES FOR -RA. ONCE THE -RA OVERSPREADS THE AREA LATER THIS
MORNING...SATURATION OF THE LOW LEVEL AIR MASS SHOULD RESULT IN MVFR
CIGS DEVELOPING BY MID-MORNING...WITH IFR EXPECTED BY EARLY
AFTERNOON. CIGS WILL THEN BE SLOW TO IMPROVE...BUT WE MAY SEE BRIEF
IMPROVEMENT TO MVFR OR EVEN VFR BY SUNDAY EVENING...JUST IN TIME FOR
ANOTHER ROUND OF -RA TO OVERSPREAD THE AREA. WINDS WILL GENERALLY
REMAIN LIGHT OUT OF THE SW...ALTHOUGH THEY MAY GO LIGHT/VRBL OR CALM
AFTER THE PRECIP SETS IN LATER THIS MORNING.

ELSEWHERE...-RA WILL GRADUALLY OVERSPREAD THE TERMINALS OVER THE
NEXT 2-4 HOURS. CIGS SHOULD ALSO LOWER DURING THAT WINDOW...WITH
MVFR CONDITIONS LIKELY AT MOST TERMINALS BY DAYBREAK. PERIODS OF
REDUCED VISBY WILL ALSO BECOME MORE LIKELY BY THAT TIME. IFR
CONDITIONS WILL BE MOST LIKELY AT KAND AND KAVL PRIOR TO 12Z...AND
TEMPOS HAVE BEEN INCLUDED TO ACCOUNT FOR THIS. OTHERWISE...CIGS
SHOULD REDUCE TO IFR OR EVEN LOWER BY MID-MORNING AT MOST TERMINALS.
IMPROVEMENT WILL BE SLOW...BUT WE MAY SEE BRIEF MVFR OR EVEN VFR
CONDITIONS BY SUNDAY EVENING...JUST IN TIME FOR ANOTHER ROUND OF -RA
TO OVERSPREAD THE AREA.

OUTLOOK...PERIODS OF RAIN AND FLIGHT RESTRICTIONS MAY LINGER FROM
LATE SUNDAY NIGHT THROUGH MONDAY NIGHT BEFORE GRADUAL IMPROVEMENT
OCCURS THROUGHOUT TUESDAY. DRY HIGH PRESSURE SHOULD RETURN BY MID-
WEEK.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH  85%     MED   79%
KGSP       HIGH  92%     LOW   43%     MED   75%     LOW   53%
KAVL       LOW   47%     LOW   41%     LOW   56%     MED   74%
KHKY       HIGH 100%     MED   62%     LOW   52%     LOW   45%
KGMU       HIGH  96%     LOW   52%     MED   75%     LOW   58%
KAND       MED   78%     HIGH  87%     LOW   47%     MED   74%

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...DEO
NEAR TERM...JDL
SHORT TERM...WIMBERLEY
LONG TERM...ARK/WIMBERLEY
AVIATION...JDL


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