Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 261335
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
835 AM EST WED NOV 26 2014

.SYNOPSIS...
LOW PRESSURE WILL INTENSIFY ALONG A STALLED COLD FRONT OFF THE
ATLANTIC SEABOARD AND MOVE UP THE COAST TODAY. AN UPPER LEVEL SYSTEM
WILL CROSS WESTERN NORTH CAROLINA EARLY THURSDAY. DRY HIGH PRESSURE
WILL RETURN FRIDAY AND LINGER INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 830 AM EST...THE WINTER WEATHER ADVISORY FOR THE CENTRAL AND
SRN NC MTNS HAS BEEN CANCELLED FOR THIS MORNING. WILL LEAVE THE NRN
MTNS WARNING/ADVISORY UP FOR A COUPLE MORE HOURS AS THESE AREAS ARE
FINALLY SEEING THE BEST SNOW RATES OF THE EVENT. HOWEVER...AMOUNTS
WILL BE MUCH LESS THAN FORECAST GIVEN THE VERY LATE TRANSITION TO
SNOW. THE SFC WARM LAYER LOOKS PLENTY DEEP TO MAKE FOR JUST A COLD
RAIN ACROSS THE FOOTHILLS AND PIEDMONT THROUGH LATE MORNING.
OTHERWISE...ANTICIPATE STEADY DRYING FROM THE SW WITH SLOWLY
REBOUNDING TEMPERATURES AHEAD OF THE NEXT SHORTWAVE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
AS OF 300 AM WED...JUST AS QUICKLY AS THE COASTAL LOW PULLS AWAY FROM
THE PIEDMONT THIS AFTN...THE NEXT SYSTEM ENTERS FROM THE WEST IN THE
FORM OF A CLIPPER SHORTWAVE ROLLING THRU THE REGION TONIGHT. MODELS
CONTINUE TO SHOW A BRIEF BUT POTENT SHOT OF Q-VECTOR CONVERGENCE AND
OMEGA WITH THIS WAVE ALONG WITH FAIRLY DEEP MOISTURE. PROFILES WILL
BE COLD ENOUGH FOR ALL SNOW IN HIGHER ELEVATIONS AT THE ONSET OF THE
FORCING AND POPS. MOST OF THE AREA HOWEVER WILL STILL BE TOO WARM FOR
SNOW AND REMAIN SO THRU THE EVENT.

TRENDS IN THE LOW LEVEL FLOW ARE A LITTLE COMPLEX WITH A VERY SHORT
RIDGE AND WEAK WAA COMING BETWEEN THE TWO TROUGHS. THERE WAS SOME
INDICATION FROM PREVIOUS MODEL RUNS THAT THIS WAA MIGHT CAUSE A SMALL
WARM NOSE TO DEVELOP AND ALLOW FOR SLEET/FZRA IN SOME OF THE
FOOTHILLS. LATEST RUNS INDICATE THIS WAA IS TOO WEAK TO HAVE SUCH AN
EFFECT AND WE WILL ADVERTISE AN ALL RAIN/SNOW EVENT. SNOW LEVELS ARE
EXPECTED TO DROP SOMEWHAT STEADILY OVERNIGHT WITH WET BULB EFFECTS
PROVIDING ONLY MARGINAL ENHANCEMENT. WITH OR JUST AFTER THE CLIPPER
AXIS PASSES EARLY THANKSGIVING MRNG...WINDS VEER TO NW AND REMAIN
BRISK THROUGH THE LOWEST FEW THSD FT WHICH SHOULD PROVIDE A JUMP IN
PRECIP RATES. THE NW WINDS CONTINUE TO BE STRONG THRU THURSDAY ALBEIT
WITH MOISTURE SLOWLY BECOMING MORE SHALLOW.

DESPITE THE STRONG FORCING MODEL QPF IS NOT THAT STRONG BUT I DID
FAVOR THE HIGHER AND MORE TERRAIN-ORIENTED NAM QPF AS PART OF A BLEND
OF RAW MODEL AND WPC QPF. TOTAL ACCUMS OF 1 TO 2 INCHES ARE EXPECTED
IN THE SMOKIES AND BALSAMS...AND 2 TO LOCALLY 3 INCHES IN THE MTNS
NORTH OF THE FRENCH BROAD. HALF OF THAT WILL PROBABLY FALL IN A SHORT
PERIOD WHEN THE TWO FORCING MECHANISMS OVERLAP. GIVEN THE HOLIDAY AND
POTENTIAL TRAVEL IMPACTS A WINTER WX ADVISORY WILL BE HOISTED FOR OUR
TENN BORDER ZONES IN ADDITION TO NRN JACKSON COUNTY MIDNIGHT TO NOON
THANKSGIVING DAY. ENOUGH WARMING SHOULD OCCUR DURING THE DAY THAT
MOST VALLEYS WILL SEE RAIN MIX IN OR A COMPLETE TRANSITION. LIGHT
SHSN COULD CONTINUE THRU FRI MRNG THOUGH MOISTURE IS INSUFFICIENT TO
EXPECT MUCH ADDITIONAL ACCUM.

DRY HIGH PRESSURE WILL FILTER IN THU NIGHT INTO FRI. MIN TEMPS FRI
MRNG WILL BE IN THE L20S MTNS AND U20S TO AROUND 30 IN THE PIEDMONT.
SKIES WILL BE MOSTLY CLEAR BY THIS TIME...BUT CONTINUED NLY WINDS
WILL KEEP TEMPS FROM RISING OUT OF THE 40S OVER MOST OF THE AREA FRI
AFTN. SLIGHT RETURN FLOW SETS UP FRI NIGHT WHICH WILL KEEP TEMPS FROM
PLUNGING AS MUCH...ALSO INTRODUCING A LITTLE CLOUD COVER INTO THE
AREA.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 220 AM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON
SATURDAY WITH A RELATIVELY ZONAL UPPER PATTERN OVER MOST OF THE
CONUS. AS WE MOVE INTO SUN...ANOTHER BROAD H5 TROF DIGS DOWN OVER
THE FAR NORTHERN STATES AND THEN OVER THE GREAT LAKES. AT THE SAME
TIME...FLAT UPPER RIDGING WILL PERSIST SPREAD OVER THE GULF OF MEX
AND PERSIST OVER THE REGION THRU MOST OF THE PERIOD. THE LONG RANGE
GUIDANCE ACTUALLY HAS THE RIDGE AMPLIFYING TOWARDS THE VERY END OF
THE MEDIUM RANGE.

AT THE SFC...HIGH PRESSURE WILL BE CENTERED OVER THE FCST AREA AT
THE START OF THE PERIOD WITH WARMER SLY FLOW INCREASING THICKNESSES
AND TEMPS OVER THE WEEKEND. THE NEXT FRONTAL SYSTEM WILL APPROACH
THE AREA BY EARLY MON AND LAY DOWN ACROSS OUR NORTHERN FRINGE.
STRONG HIGH PRESSURE BEHIND THE FRONT WILL SLIDE EASTWARD AND
APPEARS TO SET UP A POTENTIALLY STRONG CAD PATTERN TO OUR NE BY DAY
7. THE ECMWF AND CANADIAN OPERATIONAL MODELS REMAIN MORE MOIST WITH
THIS FRONT AND SUBSEQUENT WEDGE PATTERN...YET AS WE HAVE SEEN MANY
TIMES BEFORE...MODELS TEND TO OVERESTIMATE THE EXTENT OF THE DEEPER
LYR MOISTURE IN THESE SCENARIOS. WITH THAT SAID...THE ONLY POPS I
HAVE ARE SLIGHT TO LOW END SOLID CHANCE FROM LATE SUN ONWARD. THE
BEST CHANCES ARE STILL OVER THE HIGHER TERRAIN AND ALONG THE NC/TENN
BORDER REGION. TEMPS WILL WARM THRU MON WITH VALUES EXCEEDING
CLIMATOLOGY. VALUES SHOULD COOL AGAIN AS WE GO INTO MID WEEK AND THE
FLOW BECOMES MORE NELY.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...IFR/LIFR CIGS FINALLY DEVELOPED WITHIN THE PAST HOUR...AND
ARE EXPECTED TO COME IN AND OUT OVER THE FIRST FEW HOURS OF THE
PERIOD...WARRANTING A TEMPO THROUGH 15Z. OTHERWISE...OCNL MVFR VISBY
RESTRICTIONS IN -RA WILL CONTINUE AS WELL...WITH RAIN EXPECTED TO
TAPER OFF BY NOON. MVFR CIGS SHOULD THEN LIFT TO VFR NO LATER THAN
MID-AFTERNOON. VFR CLOUDS SHOULD THEN LINGER INTO THE OVERNIGHT...AS
MOISTURE PERSISTS IN ADVANCE OF A SECONDARY UPPER AIR DISTURBANCE.
THIS MAY BRING A STRAY RAIN SHOWER NEAR THE TERMINAL TONIGHT...BUT
PROBABILITY APPEARS TO REMOTE TO INCLUDE IN THE TAF ATTM. WINDS WILL
REMAIN NORTHERLY...THIS MORNING...INCREASING TO AROUND 10 KTS...THEN
TURNING GRADUALLY TOWARD THE NW AS SURFACE LOW PRESSURE MOVES UP THE
MID-ATLANTIC COAST.

ELSEWHERE...SPORADIC IFR/LIFR CIGS HAVE DEVELOPED ACROSS THE AREA
THIS MORNING...AND OCNL CIGS WILL PERSIST AT THIS LEVEL THROUGH 14
OR 15Z...WARRANTING A TEMPO THROUGH THAT TIME. OTHERWISE...OCCL MVFR
VISBY RESTRICTIONS IN -RA WILL CONTINUE AS WELL...WITH RAIN EXPECTED
TO TAPER OFF BY 15Z OR SO AT MOST TERMINALS. SNOW IS NO LONGER
EXPECTED TO MIX WITH THE RAIN AT KAVL. MVFR CIGS SHOULD THEN LIFT TO
VFR BY NOON-ISH. VFR CLOUDS SHOULD THEN LINGER INTO THE
OVERNIGHT...AS MOISTURE PERSISTS IN ADVANCE OF A SECONDARY UPPER AIR
DISTURBANCE. THIS MAY BRING A STRAY RAIN SHOWER NEAR THE TERMINALS
(SNOW SHOWERS POSSIBLE AT KAVL) TONIGHT...BUT PROBABILITY APPEARS TO
REMOTE TO INCLUDE IN THE TAF ATTM.

OUTLOOK...A DRY AIR MASS WILL THEN RETURN TO THE AREA BY LATE
THURSDAY AND CONTINUE THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-12Z
KCLT       MED   77%     HIGH  97%     HIGH 100%     HIGH 100%
KGSP       MED   77%     HIGH  95%     HIGH 100%     HIGH 100%
KAVL       MED   79%     HIGH 100%     HIGH 100%     HIGH  98%
KHKY       MED   78%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       MED   79%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  88%     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...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NCZ501-503-
     505.
     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
     THURSDAY FOR NCZ033-048>052-058-059.
     WINTER STORM WARNING UNTIL NOON EST TODAY FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...JDL
NEAR TERM...HG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
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.