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 251457
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
957 AM EST TUE NOV 25 2014

.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE AREA THIS MORNING AND STALL ALONG
THE SOUTHEAST COAST. LOW PRESSURE WILL DEVELOP ALONG THIS FRONT AND
MOVE UP THE ATLANTIC SEABOARD WEDNESDAY. AN UPPER LEVEL SYSTEM WILL
CROSS WESTERN NORTH CAROLINA EARLY THURSDAY. DRY HIGH PRESSURE WILL
RETURN FRIDAY AND LINGER INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM EST...NO CHANGES TO THE HAZARDS WILL BE MADE PENDING A
FULL REVIEW OF THE 12Z MODEL DATA. IT IS BECOMING INCREASINGLY
LIKELY HOWEVER THAT THE ADVISORY AREA MAY BE EXPANDED SLIGHTLY E AND
SOUTH THIS AFTN.

OTHERWISE...THE SFC COLD FRONT HAS FINALLY SLIPPED JUST SE OF THE
AREA THIS MORNING...WITH ASSOCIATED LOW LEVEL DRYING. EXTENSIVE HIGH
CLOUDS SHOULD PERSIST AND SLOWLY START TO LOWER THROUGH THE
DAY...WHICH ALONG WITH WEAK COLD ADVECTION WILL SLOW DIURNAL
HEATING. ONLY THE SW MTNS SHOULD SEE APPRECIABLE CLEARING OF THE MID
AND HIGH CLOUDS BEFORE THEY START TO BUILD BACK W AS THE UPPER
TROUGH SHARPENS UP.

THE POTENT SOUTHERN STREAM SHORT WAVE TROUGH WILL EJECT FROM
TX/NORTHWEST GULF OF MEXICO LATER TODAY...INITIATING CYCLOGENESIS BY
THIS AFTERNOON ACROSS THE NORTHEAST GULF. LOW PRESSURE IS THEN
EXPECTED TO DEEPEN AS IT MOVES NORTHEAST AND REDEVELOPS OFF THE
SOUTHEAST ATLANTIC COAST IN CLASSIC MILLER A FASHION. AS THIS
OCCURS...A BAND OF STRONG/DEEP FRONTOGENETICAL FORCING WILL BECOME
ESTABLISHED ACROSS THE CAROLINAS...RESULTING IN PRECIP DEVELOPMENT
AS FAR WEST AS THE SOUTHERN APPALACHIANS BY LATE EVENING. THERMAL
PROFILES SUPPORT PRIMARILY A SNOW EVENT ABOVE ABOUT 3000 FEET ACROSS
THE NORTHERN NC MTNS...AND ABOVE 4000 FEET OR SO ACROSS THE SOUTHERN
AND CENTRAL MTNS...WITH PRECIP LIKELY ENDING AS SNOW OR A RAIN/SNOW
MIX IN THE LOWER VALLEYS. WITH LIQUID EQUIV QPF EXPECTED TO BE IN
THE NEIGHBORHOOD OF 0.50 INCHES FROM ROUGHLY THE BLUE RIDGE COUNTIES
EAST...THERE IS THE POTENTIAL FOR BORDERLINE HEAVY SNOWFALL CRITERIA
ACROSS MUCH OF THE NORTHERN MTNS. THE CURRENT WARNING FOR AVERY AND
ADVISORIES FARTHER S WILL REMAIN IN PLACE PENDING A FULL REVIEW OF
12Z MODEL DATA.

OTHERWISE...AN ALL RAIN EVENT IS GENERALLY EXPECTED ACROSS THE
PIEDMONT/ FHILLS...WITH RAINFALL AMOUNTS IN THE 0.5-1.0 INCH RANGE
EXPECTED FROM THIS EVENING THROUGH WED MORNING.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUE...SFC LOW WILL CONTINUE TO LIFT UP THE EAST COAST
LATE WED WITH THE AXIS OF THE LONGWAVE UPPER TROUGH REACHING THE SRN
APPALACHIANS AROUND 06Z THU. EMBEDDED WITHIN IS A CLIPPER SHORTWAVE
WHICH SHOULD PROVIDE A BURST OF OMEGA CONCURRENT WITH DEEP LAYER
SATURATION. THUS...WHILE NEARLY ALL OF THE PIEDMONT WILL SEE PRECIP
END WED AFTN...THERE LOOKS TO BE ONLY A BRIEF LULL IN THE MTNS BEFORE
THE ARRIVAL OF THE CLIPPER. A PERIOD OF DYNAMICALLY DRIVEN
PRECIP...MAINLY SNOWFALL...IS EXPECTED IN THE MTNS AT THIS TIME.
HOWEVER IN THE WAKE OF THE WAVE THE FLOW WILL VEER TO NW...ALLOWING
LIGHT OROGRAPHIC SNOWFALL TO CONTINUE THRU THURSDAY NIGHT.

TEMPS DURING WED AFTN WILL BE WARM ENOUGH FOR RAIN THROUGHOUT THE
CWFA BUT WILL DIP NEAR OR BELOW FREEZING DIURNALLY IN THE EARLY
EVENING. SIMULTANEOUSLY...JUST AHEAD OF THE INCOMING WAVE...THE GFS
AND PARTICULARLY THE NAM SHOW A BRIEF PERIOD OF SOUTHERLY LLVL FLOW
AND WAA AROUND 900 MB. THIS MAY LEAD TO THE DEVELOPMENT OF A SMALL WARM
NOSE AND COULD ALLOW SLEET OR FREEZING RAIN TO BRIEFLY OCCUR IN SOME
OF THE HIGHER ELEVATIONS. HOWEVER BY THE TIME THE DEEPER MOISTURE ARRIVES
AND RATES PICK UP THE FLOW SHOULD HAVE VEERED AGAIN AND NEUTRAL TO
COLD ADVECTION WILL AGAIN LEAD TO ALL-SNOW PROFILES WHICH PERSIST
THRU WED NIGHT. THE CONTINUING NW FLOW ACTIVITY LOOKS TO CHANGE TO
RAIN IN THE LOWER ELEVATIONS THU BEFORE CHANGING BACK TO ALL SNOW FOR
THU NIGHT. WHILE THE MOISTURE PROFILES AND WINDS REMAIN STEADILY
FAVORABLE THRU THURSDAY THE MOISTURE BECOMES AN ISSUE THU NIGHT WHEN
ACCUMULATIONS SHOULD BECOME MINIMAL.

TEMPS REMAIN BELOW CLIMO THRU THURSDAY...THOUGH SOME REBOUND WILL BE
NOTED OUTSIDE THE NW FLOW AREAS ON THU UNDER DOWNSLOPING WINDS AND
MOSTLY CLEAR SKIES. THE CONTINUED COLD ADVECTION HOWEVER WILL ALLOW
THICKNESSES TO CONTINUE DROPPING THU NIGHT...AND BRING LOWS INTO THE
20S ACRS MOST OF THE AREA FRI MRNG.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 330 AM TUE...LITTLE CHANGE FROM THE PREVIOUS FORECAST FOR
THE MEDIUM RANGE. DRY HIGH PRESSURE WILL PREVAIL ACRS THE SOUTHEAST
FRI IN THE WAKE OF THE DEPARTING UPPER TROUGH. THIS HIGH SETS UP
OFFSHORE SATURDAY AS THE UPPER FLOW BECOMES ESSENTIALLY ZONAL. A
POTENT NRN STREAM LOW WILL MOVE ACRS ONTARIO AND QUEBEC SAT NIGHT
INTO SUNDAY PULLING A COLD FRONT INTO THE OHIO VALLEY. SWLY RETURN
FLOW WILL RETURN ENOUGH MOISTURE INTO THE AREA OVER THE WEEKEND THAT
BY SUNDAY SCHC POPS RETURN TO THE SW MTNS. POPS SLOWLY RETURN OVER
MORE OF THE AREA THRU EARLY NEXT WEEK AS THE COLD FRONT SAGS IN FROM
THE NORTH. GIVEN THE WARM SFC FLOW...TEMPS WILL MODERATE TO NEAR
CLIMO BY LATE WEEKEND.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
AT KCLT...LOW LEVEL DRYING CONTINUES IN THE POST FROPA AIR...AND NO
FURTHER RESTRICTIONS ARE EXPECTED TODAY. THE MID AND HIGH CLOUDS
WILL INCREASE AND THICKEN...HOWEVER...AS THE UPPER LEVEL TROUGH
SHARPENS UP TO THE WEST. SFC WINDS WILL TURN N/NE THROUGH THE AFTN
AND EVENING AS SURFACE LOW PRESSURE DEVELOPS OFF THE SOUTHEAST
COAST. THIS FEATURE WILL SPREAD MOISTURE AND RAIN INTO THE PIEDMONT
BY AROUND MIDNIGHT...WITH RESTRICTIONS...AT LEAST MVFR...POSSIBLY
LOWER...EXPECTED BY THE END OF THE PERIOD.

ELSEWHERE..VFR CONDITIONS AND LIGHT NW WINDS ARE EXPECTED THROUGH
MUCH OF THE TAF PERIOD...ALTHOUGH THERE WILL PROBABLY BE A BRIEF
PERIOD OF LGT/VRBL WINDS THIS AFTERNOON. MID AND HIGH CLOUDS WILL
GRADUALLY THICKEN AND LOWER. LOW PRESSURE DEVELOPING OFF THE
SOUTHEAST COAST WILL SPREAD MOISTURE AND PRECIPITATION INTO THE
PIEDMONT BY AROUND MIDNIGHT...WITH RESTRICTIONS...AT LEAST MVFR...
POSSIBLY LOWER...EXPECTED BY THE END OF THE PERIOD. WHILE RAIN IS
EXPECTED OUTSIDE THE MTNS...RAIN MAY MIX WITH SNOW AT KAVL BY THE
END OF THE PERIOD...BUT WILL LEAVE THIS TO BE FURTHER EVALUATED BY
THE NEXT FORECASTER.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL
GRADUALLY IMPROVE WEDNESDAY...WITH MOST LOCATIONS LIKELY RETURNING
TO VFR DURING THE AFTERNOON. ANOTHER ROUND OF SCATTERED RAIN SHOWERS
SOUTH/SNOW SHOWERS NORTH WILL IMPACT THE AREA WED NIGHT INTO THU
MORNING. A DRY AIR MASS WILL RETURN TO THE AREA DURING LATE WEEK.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH  97%     HIGH  86%
KGSP       HIGH 100%     HIGH 100%     HIGH  97%     HIGH  91%
KAVL       HIGH 100%     HIGH 100%     HIGH  88%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  80%
KGMU       HIGH 100%     HIGH 100%     HIGH  97%     HIGH  91%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  83%

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...WINTER STORM WARNING FROM 9 PM THIS EVENING TO 4 PM EST
     WEDNESDAY FOR NCZ033.
     WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON EST
     WEDNESDAY FOR NCZ052-053-059-064.
     WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 4 PM EST
     WEDNESDAY FOR NCZ049-050.
SC...NONE.

&&

$$
SYNOPSIS...CSH/HG
NEAR TERM...HG/JDL
SHORT TERM...WIMBERLEY
LONG TERM...ARK/WIMBERLEY
AVIATION...HG/JDL



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