Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 241739
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1239 PM EST SAT JAN 24 2015

.SYNOPSIS...
LOW PRESSURE WILL MOVE UP THE EAST COAST TODAY. HIGH PRESSURE WILL
BRIEFLY BUILD IN ON SUNDAY...BEFORE A LOW PRESSURE SYSTEM AND
TRAILING UPPER LEVEL DISTURBANCE AFFECT THE AREA SUNDAY NIGHT
THROUGH TUESDAY. HIGH PRESSURE WILL BUILD OVER THE AREA DURING THE
MIDDLE TO LATE PART OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1235 PM...SNOW SHOWERS HAVE GREATLY DIMINISHED ACROSS THE
MTNS...BUT SOME LINGERING LIGHT SNOW SHOWERS OF FLURRIES ACROSS THE
MTN MTNS WILL DISSIPATE BY MID AFTERNOON. CLOUDS WILL SLOWLY
DIMINISH AS WELL. ADDITIONAL ACCUMS EXPECTED. LOW CLOUDS WILL SOON
CLEAR OUTSIDE OF THE MTNS WITH ONLY FEW CLOUDS REMAINING. TEMPS WILL
WARM NEAR FCST HIGHS AS A RESULT. GUSTY WINDS ACROSS THE AREA THIS
AFTERNOON WILL DIMINISH THIS EVENING.

AS OF 935 AM...RAIN HAS CHANGED TO SNOW ACROSS THE MTNS...BUT
COVERAGE IS RAPIDLY DECREASING AS THE DEFORMATION ZONE MOVES EAST
ACROSS THE AREA. ACCUMS SHUD REMAIN SOLIDLY IN THE ADVISORY RANGE
WITH BEST ACCUMS OVER THE HIGHER ELEVATIONS OF THE NRN MTNS. AS THIS
FORCING HAS MOVED EAST...PRECIP HAS BLOSSOMED ONCE AGAIN OUTSIDE OF
THE MTNS. EXPECT ALL THIS PRECIP TO MOVE EAST OF THE AREA BY 18Z.
CLEARING IS OCCURRING IN THE LEE OF THE MTNS ACROSS THE UPPER
SAVANNAH RIVER VALLEY AS DOWNSLOPE FLOW DEVELOPS. EXPECT THIS
CLEARING TO SLOWLY INCREASE THRU THE MORNING AS LOW LEVEL MOISTURE
IS SCOURED BY THE DEVELOPING DOWNSLOPE FLOW. THAT SAID...CLOUD AND
FOG MAY GET WORSE BEFORE THE SCOURING CAN OCCUR. GUSTY WINDS STILL
EXPECTED TO DEVELOP...BUT WILL REMAIN BELOW WIND ADVISORY
CRITERIA...EXCEPT ACROSS THE HIGHEST PEAKS OF THE MTNS. TEMPS LOOK
ON TRACK.

AS OF 650 AM...ANOTHER BAND OF -RA/DZ HAS BLOSSOMED ACROSS THE HEART
OF THE CWA THIS MORNING...BUT SHOULD MOVE QUICKLY EAST OVER THE NEXT
COUPLE OF HOURS. MEANWHILE...TEMPS HAVE FELL QUICKLY INTO THE 20S
ABOVE ABOUT 4000 FEET DURING THE PAST COUPLE OF HOURS...IN ADVANCE
OF DEFORMATION ZONE BAND. RADAR REPRESENTATION OF THIS BAND IS
LOOKING LESS IMPRESSIVE WITH TIME...BUT STILL MAY BE ENOUGH TO
PRODUCE SOME DECENT SNOWFALL RATES ACROSS THE HIGHER ELEVATIONS OVER
THE NEXT COUPLE OF HOURS. VALLEY TEMPS REMAIN IN THE UPPER 30S AT
THIS HOUR...BUT SNOW LEVELS SHOULD FALL TO THE VALLEY FLOORS JUST IN
TIME FOR THE PRECIP TO TAPER OFF.

SPORADIC BANDS OF LIGHT TO MODERATE RAIN...ASSOCIATED WITH LOW-TO-
MID LEVEL FRONTOGENESIS WILL CONTINUE TO PUSH EAST ACROSS THE
PIEDMONT THIS MORNING...WITH PRECIP CHANCES ENDING FOR MOST AREAS
EAST OF THE MTNS...AS MID/UPPER LEVEL DRYING OCCURS ON THE AC SHEAR
SIDE OF THE UPPER JET. MEANWHILE...DEFORMATION ZONE BAND CONTINUES
TO PROGRESS STEADILY ACROSS THE TENN VALLEY AND CUMBERLAND PLATEAU
AREA THIS MORNING...WITH PRIMARILY LIGHT RETURNS INDICATED ON
REGIONAL 88DS. TEMPS HAVE BEGUN TO FALL SLOWLY ACROSS THE HIGHER
ELEVATIONS OF THE NC MTNS THIS MORNING...AND BY THE TIME THIS BAND
OF PRECIP REACHES WESTERN NC (BY AROUND DAYBREAK)...AREAS ABOVE 3000
FEET OR SO SHOULD BE COLD ENOUGH FOR SNOW. IN FACT...SNOW LEVELS
WILL FALL RATHER QUICKLY AFTER 09Z...AND I EXPECT MOST OF THE
MTNS... EVEN THE LOWER VALLEYS WILL SEE AT LEAST A FEW FLAKES BEFORE
THE DEFORMATION BAND PUSHES EAST AROUND MID-MORNING. STILL EXPECT
THE MORE SIGNIFICANT ACCUMS (2-3 INCHES TO BE CONFINED TO AREAS
ABOVE 3500 FEET...BUT SOME VALLEY LOCATIONS COULD PICK UP A QUICK
DUSTING TO AN INCH...ESP NEAR THE TENN BORDER.

SHORT TERM GUIDANCE INDICATES MOISTURE WILL DRY UP VERY QUICKLY
LATER THIS MORNING IN THE W/NW FLOW REGIME...SO POPS FALL TO LESS
THAN SLIGHT CHANCE BY 18Z...BY WHICH TIME SKIES SHOULD BE CLEAR IN
MOST AREAS...EXCEPT PERHAPS THE IMMEDIATE TENN BORDER. GUSTY NW
WINDS CAN BE EXPECTED OVER THE MTNS TODAY...WITH GUSTS OF AROUND 40
MPH LIKELY IN THE HIGH ELEVATIONS. TEMPS WILL REBOUND TO NEAR NORMAL
THANKS TO DOWNSLOPE WARMING EAST OF THE MTNS...WHILE MOST OF THE
HIGH TERRAIN WILL SEE MAXES 5-10 DEGREES BELOW CLIMO.

MOISTURE MAKES A BRIEF RETURN TO THE SOUTHERN APPALACHIANS
TONIGHT...AS A WEAK VORT MAX DROPS INTO THE BASE OF THE DEVELOPING
BROAD LONG WAVE TROUGH. HOWEVER...IT/S DEBATABLE WHETHER MOISTURE
WILL BE DEEP ENOUGH TO SUPPORT ADDITIONAL SNOW SHOWERS. A TOKEN
SLIGHT CHANCE WILL BE MAINTAINED...BUR PRIMARILY LIMITED TO THE NRN
MTNS.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AT 230 AM EST SATURDAY...ON SUNDAY MORNING A MEAN UPPER TROUGH WILL
BE OVER THE EASTERN PORTION OF THE CONTINENT...WHILE AN UPPER RIDGE
WILL BE OVER THE NW USA...AND A CLOSED LOW WILL BE OFF BAJA CA. ONE
SHORTWAVE WILL BE EXITING THE EAST COAST...WHILE A CLOSED LOW DIVES
SE ACROSS THE PLAINS AND MID MS RIVER VALLEY INTO THE BASE OF THE
TROUGH. THE UPPER LOW OPENS UP SUNDAY NIGHT AS IT REACHES THE
SOUTHERN APPALACHIANS...WHILE WHAT WAS CHANNELED VORTICITY TO ITS
SOUTH...BECOMES ADVECTED VORTICITY FROM NC TO LA. THE LOW CROSSES
THE CAROLINAS ON MONDAY... MOVING OFF THE COAST MONDAY NIGHT...
FOLLOWED BY A SLUG OF CHANNELED VORTICITY TOWARD DAWN.

AT THE SURFACE...A COLD FRONT WILL APPROACH THE SOUTHERN
APPALACHIANS FROM THE WEST ON SUNDAY...SPREADING PRECIPITATION EAST
ACROSS THE AREA IN THE AFTERNOON. THICKNESS VALUES WILL BE RATHER
LOW ACROSS THE AREA...BUT MODEL SOUNDINGS SUGGEST PRECIPITATION WILL
START AS RAIN AT ALL BUT THE HIGHEST MOUNTAIN ELEVATIONS.
PRECIPITATION WILL CONTINUE SUNDAY NIGHT BEHIND THE FRONT UNDER THE
UPPER LOW...WITH SNOW LEVELS DROPPING TO THE MOUNTAIN VALLEY
FLOORS...WHILE RAIN CONTINUES IN THE LEE OF THE MOUNTAINS. AS THE
UPPER LOW MOVES OFF TO THE EAST ON MONDAY...RAIN WILL SLOWLY DIMINISH
FROM THE WEST IN THE LEE OF THE MOUNTAINS...WHILE A NW FLOW SNOW
EVENT SETS UP IN THE NC MOUNTAINS...WHICH CONTINUES THROUGH MONDAY
NIGHT. TEMPERATURES WILL START OUR SLIGHTLY ABOVE NORMAL AHEAD OF
THE FRONT...FALLING TO SLIGHTLY BELOW NORMAL BEHIND IT.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AT 230 AM EST SATURDAY...ON TUESDAY MORNING AN UPPER TROUGH WILL BE
OVER THE EASTERN USA...WITH A RIDGE OVER THE EASTERN ROCKIES...AND
AND UPPER LOW NEAR THE CA COAST. THE MODELS VARY ON THE DEGREE OF
DEAMPLIFICATION THAT OCCURS OVER THE EAST INTO TUESDAY...BUT
BASICALLY AGREE ON A MORE ZONAL UPPER FLOW OVER THE SOUTHEAST BY
LATE THURSDAY. THERE IS GOOD MODEL AGREEMENT ON REAMPLFICATION OF
THE EASTERN TROUGH FROM FRIDAY INTO SATURDAY.

A COLD FRONT WILL BE MOVING SOUTH OVER THE GULF OF MEXICO TUESDAY
MORNING...WHILE MOIST NW FLOW PERSISTS INTO THE NC MOUNTAINS. SNOW
SHOWERS ASSOCIATED WITH THIS FLOW WILL GRADUALLY DIMINISH...AS HIGH
PRESSURE MOVES FROM THE PLAINS TO THE OH RIVER VALLEY BY WEDNESDAY.
THIS HIGH DRIFTS TOE THE EAST COAST BY THURSDAY...WHILE A PAIR OF
COLD FRONTS MOVE SE THROUGH THE MS RIVER VALLEY. THE FRONTS CROSS
OUR AREA FROM THE NW ON THURSDAY NIGHT...ACCOMPANIED BY MODEST
MOISTURE AND LIMITED POTENTIAL FOR RAINFALL. SOME LINGERING MOISTURE
ALONG THE TN BORDER MAY RESULT IN NW FLOW SNOW SHOWERS IN THE NC
MOUNTAINS ON THURSDAY NIGHT AND FRIDAY...BRIEFLY CHANGING TO RAIN
BEFORE ENDING FRIDAY NIGHT.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...SAT PIX SHOW THE BACK EDGE OF THE CLOUDS VERY CLOSE TO THE
AIRFIELD. EXPECT VFR WILL DEVELOP BEFORE 18Z...SO STARTED THE TAF AS
SUCH. ALL GUIDANCE SHOWS WINDS GOING BACK WNW FOR THE AFTERNOON...SO
HAVE WINDS THERE AS WELL. CANNOT RULE OUT SOME LOW END GUSTS...BUT
THINK 11 KTS WILL HOLD FOR THE BULK OF THE DAY. WINDS GO LIGHT WNW
THIS EVENING THEN TURN LIGHT SLY AS MIXING BEGINS SUN MORN. THE FEW
LOW VFR CLOUDS THIS AFTERNOON DISSIPATE THIS EVENING WITH CIRRUS THE
MAIN CLOUD LEVEL THRU THE REST OF THE PERIOD.

ELSEWHERE...KAVL WILL SEE A TEMPO MVFR CIG EARLY THIS AFTERNOON AS
MTN WAVE CLOUDS FORM IN THE NWLY FLOW AND LINGERING LOW LEVEL
MOISTURE. HOWEVER...THE MOISTURE ERODES THRU THE AFTERNOON WITH ONLY
SCT CLOUDS EXPECTED. LOW LEVEL MOISTURE RETURNS OVERNIGHT...BUT IT
IS MUCH MORE SHALLOW. THEREFORE...EXPECT ANY CLOUDS TO REMAIN NORTH
OF THE AIRFIELD OVERNIGHT. GUSTY NNW WINDS CONTINUE THRU THE
AFTERNOON AND DIMINISH OVERNIGHT. LIGHT SLY WIND DEVELOPS SUN MORN.
THE REST OF THE SITES WILL SEE A FEW LOW VFR CLOUDS THIS AFTERNOON
THEN CIRRUS FOR THE REST OF THE PERIOD. W TO NW GUSTY WINDS WILL
DIMINISH THIS EVENING THEN TURN LIGHT S TO SW SUN MORN.

OUTLOOK...A SERIES OF CLIPPER SYSTEMS WILL BRING SNOW CHANCES TO THE
AREA EARLY IN THE WEEK...MAINLY TO THE MTNS NORTH AND WEST OF KAVL.
VFR IS LIKELY ELSEWHERE.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       MED   66%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       LOW   58%     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...JAT
NEAR TERM...JDL/RWH
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...RWH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.