Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 091758
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1258 PM EST TUE FEB 9 2016

.SYNOPSIS...
A BROAD AND MOIST AREA OF LOW PRESSURE WILL SLOWLY CROSS THE REGION
THROUGH WEDNESDAY NIGHT. CANADIAN HIGH PRESSURE WILL THEN BUILD IN
THURSDAY AND REMAIN THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1250 PM EST TUESDAY...CONTINUING TO SEE LIGHT RETURNS ON RADAR
OUTSIDE OF THE MTNS...SPECIFICALLY ACROSS THE LAKELANDS REGION OF
THE WESTERN UPSTATE AND NORTHEAST GA WHERE A FEW POCKETS OF LIGHT
SNOW SHOWERS HAVE BEEN REPORTED...WITH FLURRIES OBSERVED AS FAR
EAST AS GSP.  OTHERWISE...NWFS CONTINUES TO DOMINATE THE WX OVER
THE HIGH TERRAIN THIS AFTERNOON WHERE MODERATE/HEAVY BANDING OF
SNOW SHOWERS HAS BEEN REPORTED.  THE MOST ABUNDANT OF WHICH HAS
DIMINISHED SOMEWHAT ASSOCIATED WITH A CONVERGENCE AXIS OVER THE
GREAT TN VALLEY...WHICH PRODUCED NEARLY 1-2 HOURS OF HEAVY SNOW
ACROSS MADISON/YANCEY COUNTIES.  LOOKING UPSTREAM...STILL SEEING
AMPLE MOISTURE TO YIELD CONTINUED SNOWFALL...THUS THE FCST WAS
UNCHANGED OVER THE IMMEDIATE NEAR TERM.  FULL FCST DISCUSSION TO
FOLLOW WITHIN THE HOUR.

PREVIOUS DISCUSSION...DEEP UPPER TROUGH WITH EMBEDDED CYCLONE
NOW SITS OVER VIRTUALLY THE ENTIRE EASTERN CONUS. A KINK IN THE
CIRCULATION IS SWINGING ACROSS ERN KY/TN...AND A BROAD AREA OF
LIGHT SNOW EXTENDS FROM NEAR KNOXVILLE TO NEAR PITTSBURGH AHEAD
OF IT. SOME OF THIS MOISTURE AND WESTERLY LLVL FLOW WILL CONTINUE
TO INTERCEPT THE SRN APPALACHIANS THRU THE MORNING. BASED ON THE
FEW SFC OBS AND WEBCAMS AVAILABLE FROM NEAR THE SPINE OF THE
MOUNTAINS...THE ACCUM SINCE SNOW BEGAN YESTERDAY IS GENERALLY
UNDER 2 INCHES. PEAK RATES FROM THIS PHASE OF THE EVENT HAVE
ALREADY OCCURRED. THOUGH SNOW WILL CONTINUE TODAY...WINDS ARE
EXPECTED TO BACK AND UPPER FORCING TO WEAKEN AS THAT SHORTWAVE
KINK MOVE EAST OF THE CHAIN...SO THE UPSLOPE FORCING WILL WEAKEN
ACCORDINGLY. SHORT RANGE GUIDANCE SEEMS TO HAVE PICKED UP ON THIS
AS THE CONSENSUS IS THAT RATES WILL SLOW...AND A LULL IN SNOW
WILL OCCUR DURING THE DAY. WINDS BECOME MORE FAVORABLE AGAIN BY
THIS EVENING...AND ANOTHER LOBE OF THE TROUGH WILL PASS AS WELL
PROVIDING A BOOST ALOFT. THUS THE SNOW SHOULD PICK BACK UP THIS
EVENING...THIS ALSO BACKED UP BY SHORT RANGE GUIDANCE. WHILE I FEEL
THE HIGHER-RES GUIDANCE IS DOING A GOOD JOB WITH THE TRENDS...I
AM RELUCTANT TO USE ITS RELATIVELY HIGH QPF...WHICH WAS OVERDONE
MONDAY. WE WILL LET THE WINTER STORM WARNING EXPIRE AT 12Z AS
EXPECTED...THEN HOIST A WINTER WEATHER ADVISORY FOR THE NC MTNS
PLUS RABUN COUNTY...GOING THRU 6 AM TOMORROW. WE WILL KEEP THE
WIND CHILL ADVISORY AS-IS GIVEN THE CONTINUED COLD ADVECTION AND
MODEST GRADIENT FLOW STILL POISED TO BRING WIND CHILLS FROM 5 TO
15 BELOW ZERO IN THE HIGHER ELEVATIONS BY DAYBREAK WED.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 335 AM TUESDAY...NW FLOW SNOW WILL BEGIN WINDING DOWN WED AS
AS THE MOISTURE AND WIND DIMINISH. COULD SEE ANOTHER HALF INCH IN
THE USUAL LOCATIONS BEFORE THE SNOW SHOWERS TURN MORE TO FLURRIES
THEN END WED NITE. ALTHOUGH WINDS WILL DIMINISH...THEY WILL BE HIGH
ENUF AND TEMPS COLD ENUF FOR HIGH ELEVATION WIND CHILLS TO FALL BACK
INTO THE ADVISORY RANGE. HIGHS ACROSS THE MTNS WILL BE NEAR THE
NORMAL LOWS...AND UP TO 15 DEGREES BELOW NORMAL ELSEWHERE. LOWS WILL
BE 10 TO 15 DEGREES BELOW NORMAL.

A WEAK CLIPPER SYSTEM WILL DROP INTO THE AREA THU AND EAST OF THE
AREA THU NITE. GUIDANCE IS IN DISAGREEMENT ON THE AMOUNT OF MOISTURE
AND ANY RESULTING PRECIP. THEREFORE...HAVE KEPT A DRY FCST FOR NOW
AS EVEN THE WETTEST MODEL DOES NOT HAVE ANY SIGNIFICANT SNOWFALL.
THICKNESSES RISE AHEAD OF THE CLIPPER BRINGING A WARMING TREND
ACROSS THE CWFA. HIGHS WILL /ONLY/ BE 10 TO 15 DEGREES BELOW NORMAL
WHILE LOWS END UP AROUND 10 DEGREES BELOW NORMAL. WITH THE INCREASE
IN TEMPS AND RELATIVELY LIGHT WINDS...WIND CHILL VALUES SHUD REMAIN
ABOVE ADVISORY LEVELS THU NITE.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 355 AM TUESDAY...MUCH BETTER AGREEMENT IN THE MEDIUM RANGE
GUIDANCE THIS MORNING...AT LEAST UNTIL THE END OF THE PERIOD. THE
DEEP ERN CONUS TROF WILL REMAIN IN PLACE THRU SAT. SHORT WAVES
ROTATING THRU THE TROF BRING AN ARCTIC FRONT ACROSS THE AREA WITH A
RETURN OF A VERY COLD AIR MASS. THERE COULD BE SOME LIGHT NW FLOW
SNOW BEHIND THE FRONT...BUT IT LOOKS TO BE LESS THAN ADVISORY LEVEL
SNOWFALL FOR NOW. HIGHS FRI RISE A COUPLE OF DEGREES FROM THU AHEAD
OF THE ARCTIC FRONT...THEN DROP PRECIPITOUSLY THRU SUN BEHIND THE
FRONT. IN FACT...HIGHS SUN WILL BE NEAR THE NORMAL LOWS FOR THIS
TIME OF YEAR...WITH LOWS UP TO 15 TO 20 DEGREES BELOW NORMAL. WITH
THE COLD TEMPS AND INCREASING WINDS BEHIND THE FRONT...VERY LOW WIND
CHILL VALUES WILL RETURN AS WELL. HIGH ELEVATION ADVISORY LEVEL WIND
CHILLS ARE POSSIBLE FRI NITE...WITH WIDESPREAD MTN VALLEY ADVISORY
AND HIGH ELEVATION WARNING LEVEL WIND CHILLS POSSIBLE SAT NITE.

GUIDANCE DISAGREES ON THE POTENTIAL WEATHER SYSTEM MOVING THRU ON
MON. THE GFS HAS A WEAK FRONTAL SYSTEM MOVING THRU FROM THE NW WITH
LITTLE GULF OR ATLANTIC IN FLOW. THE ECMWF HAS A STRONG FRONT MOVING
IN FROM THE WEST WITH STRONG GULF INFLOW. SURFACE AND H85 TEMPS
WOULD INDICATE SOME SNOW POTENTIAL ACROSS THE MTNS AND NRN TIER WITH
MAINLY RAIN ELSEWHERE. HAVE GONE WITH A GUIDANCE BLEND AND KEPT POP
IN THE CHANCE RANGE FOR NOW...WITH THE RAIN/SNOW LINE BASED ON
SURFACE TEMPS. CONFIDENCE IS LOW IN THIS PORTION OF THE FORECAST
WITH CHANGES LIKELY AS IT APPROACHES.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...VFR THROUGH THE PERIOD.  LIGHT SHSN CONTINUE TO BREAK
CONTAINMENT OUT OF THE NC MTNS ASSOCIATED WITH MODEST UPSLOPING
ALONG THE TN LINE.  LATEST CAM GUIDANCE DOES INDICATE A FEW
SHOWERS OVER THE NC PIEDMONT THIS AFTERNOON...HOWEVER CONFIDENCE
IS RATHER LOW THAT ANY PRECIP WOULD MAKE TO THE SFC GIVEN LARGE
TD DEPRESSIONS IN PLACE.  IF ANY PRECIP WAS OBSERVED...THINK IT
WOULD BE NOTHING MORE THAN A FEW FLURRIES.  LOW VFR STRATUS WILL
PERSIST THROUGH MUCH OF THE EVENING INTO THE OVERNIGHT HOURS ATOP
GUSTY WNW FLOW...GENERALLY TOPPING OUT AROUND 20 KTS.  GUSTS WILL
DISSIPATE AFTER MIDNIGHT WITH FLOW POSSIBLY BACKING WSW DUE TO WEAK
LEE TROFFING IN THE LEE OF THE BLUE RIDGE.  WINDS WILL INCREASE
YET AGAIN AFTER DAYBREAK OUT OF THE WNW WITH LOW END GUSTS FAVORED
AMIDST VFR ALTOCU.

AT KAVL...MODERATE NORTHWEST FLOW ALONG THE TN LINE WILL CONTINUE
TO YIELD SHSN THROUGH MUCH OF THE TAF CYCLE.  FLIGHT CATEGORIES
SHOULD REMAIN AT LOW VFR LEVELS WITH OVC STRATUS PREVAILING.
EXPECTING WINDS TO REMAIN ELEVATED IN THE 10-12KTS RANGE WITH 20KT
GUSTS ALSO BEING A POSSIBILITY THIS AFTERNOON AS FLOW CHANNELS UP
THE VALLEY.  BEYOND THAT...CONDITIONS WILL IMPROVE INTO DAYBREAK
ON WEDNESDAY AS OVC SKIES BEGIN TO SCT AND ANY RESIDUAL SNOWFALL
LIFTS NORTH OF THE FRENCH BROAD VALLEY REGION.

ELSEWHERE EAST OF THE MTNS...SIMILAR TO THAT OF KCLT ABOVE WITH
FLURRIES BEING POSSIBLE AT ALL SC SITES...WITH A BRIEF SHOT AT
SHSN FAVORED AT KHKY THROUGH THE AFTERNOON.  OTHERWISE LOW VFR
CIGS WILL PREVAIL THROUGH THE EVENING HOURS ATOP GUSTY WSW/WNW
FLOW...BEFORE GUSTS SUBSIDE AFTER MIDNIGHT...THEN INCREASE YET
AGAIN BY LATE MORNING AMIDST SCT ALTOCU.

OUTLOOK...SEVERAL STRONG UPPER DISTURBANCES EMBEDDED IN A DEEP
UPPER TROUGH WILL SWING ACROSS THE AREA THRU WEDNESDAY. MOISTURE
AND COLD AIR WILL CONTINUE TO FLOW INTO THE AREA DURING THIS
TIME PERIOD. RESTRICTIONS WILL BE POSSIBLE...PARTICULARLY IN THE
MOUNTAINS WHERE THERE ARE HIGH CHANCES OF ACCUMULATING SNOW.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  98%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  99%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR GAZ010.
NC...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR NCZ033-
     048>053-058-059-062-063.
     WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO NOON EST
     WEDNESDAY FOR NCZ033-048>052-058-059-062>064.
SC...NONE.

&&

$$
SYNOPSIS...RWH/SBK
NEAR TERM...CDG/WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CDG


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