Area Forecast Discussion
Issued by NWS Greer, SC

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519
FXUS62 KGSP 101541
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1041 AM EST WED FEB 10 2016

.SYNOPSIS...
A BROAD AND MOIST AREA OF LOW PRESSURE WILL PERSIST OVER THE
AREA THROUGH TONIGHT. CANADIAN HIGH PRESSURE WILL THEN BUILD IN
THURSDAY AND REMAIN THROUGH THE WEEKEND. HOWEVER...DEVELOPING
COASTAL SYSTEMS BRING CHANCES OF PRECIPITATION FRIDAY AND THEN
AGAIN EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030AM EST WEDNESDAY...CURRENT FCST LOOKS GOOD AS GUIDANCE
CONTINUES TO FAVOR DEPLETION OF UPSLOPE INDUCED SN SHOWERS ALONG
THE TN LINE THROUGH THE AFTERNOON INTO THE EVENING AS LLV FLOW BACKS
WESTERLY.  THUS...ONLY MINOR TWEAKS TO POPS WERE MADE WHICH YIELDED
NO SIG CHANGES.  ALSO ADJUSTED SKY TO REFLECT RECENT VIS SAT.
NO OTHER CHANGES NEEDED/MADE WITH THIS UPDATE.  SNOW TOTALS OVER
THE LAST 24 HOURS WERE FAIRLY IMPRESSIVE...PARTICULARLY ACROSS
PORTIONS OF MADISON/YANCEY COUNTIES WHERE BANDING OCCURRED...AS
WELL AS AT BEECH MTN...WHERE 24 HOUR AMOUNTS WERE IN THE 5-7 INCH
RANGE FOR BOTH LOCALES.  A GRAPHICAL ANALYSIS OF SNOWFALL TOTALS
HAS BEEN POSTED TO OUR TWITTER/FACEBOOK PAGE.

PREVIOUS DISCUSSION...PERSISTENT EASTERN CONUS TROUGH CONTINUES
TO SUPPORT MOIST WESTERLY FLOW INTO THE SRN APPALACHIANS. PER
NAM...EVER SO SLIGHT INSTABILITY IS PRESENT OVER EAST TN AND SLIGHT
NEGATIVE EPV VALUES AS WELL...WHICH WOULD ACCOUNT FOR THE SHOWERY
NATURE AND BANDING. CLOUD SHIELD REMAINS CONTIGUOUS OVER FAR EAST
TN...BUT MANY BREAKS ARE SEEN ON SATELLITE FOG PRODUCT OVER THE
CUMBERLAND PLATEAU. STILL CONFIDENT IN EXPECTING POPS BACKING OFF
THRU THIS MORNING.

THE AXIS OF THE TROUGH WILL FINALLY SWING EAST OF THE REGION
TODAY...WITH SLOW HEIGHT RISES THRU THU MORNING. A BROAD AREA OF
CHANNELED VORT WILL PROGRESS ACRS THE CWFA TODAY ACCORDINGLY. THIS
IS EXPECTED TO BRING SOME PARTIAL CLOUD COVER BACK TO THE
PIEDMONT. MOISTURE IS MORE SHALLOW THERE THAN THE PAST COUPLE OF
DAYS...AND AS SUBSIDENCE DEVELOPS IN THE WAKE OF THE WAVE ANY
SHALLOW CONVECTION WILL BE CAPPED OFF QUICKLY. THAT SAID A FEW
FLURRIES MIGHT BE SEEN BENEATH THE PIEDMONT CLOUDS...BUT NOT AS
COMMONLY AS WE SAW ON MON-TUE.

AS THE CHANNELED VORT MAX PASSES OVER THE MTNS...A COUPLE CAMS
INCLUDING THE NSSL WRF DEVELOP SOME LIGHT PRECIP OVER UPPER
EAST TN. INCLUDED A SLIGHT UPTICK IN POPS AGAIN EARLY THIS
AFTN. SOME INSTABILITY DOES REDEVELOP THERE AS WELL DESPITE THE
SUBSIDENCE. THOUGH ADDITIONAL SNOW IS EXPECTED TO BE LESS THAN
AN INCH...SOME VISIBILITY ISSUES AND SLICK SPOTS WILL PERSIST ON
HIGH-ELEVATION ROADS...SO THE WINTER WX ADVISORY WILL BE EXTENDED
THRU THE DAY TODAY. STRENGTHENING LOW LEVEL COLD ADVECTION WILL
OCCUR AS HIGH PRESSURE BEGINS TO BUILD IN TONIGHT...KEEPING THE
BOUNDARY LAYER MIXED AND RESULTING IN BLUSTERY CONDITIONS IN THE
MOUNTAINS. PREVIOUSLY ISSUED WIND CHILL ADVISORIES FOR TONIGHT
LOOK GOOD IN LIGHT OF REVISED TEMPS AND WINDS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 330 AM WEDNESDAY...ANY LINGERING NW FLOW SNOW SHOWERS WILL
QUICKLY END THU MORNING AS MOISTURE DRIES UP. LOW WIND CHILL VALUES
AT THE START OF THE DAY ACROSS THE MTNS WILL WARM ABOVE ADVISORY
LEVEL BY MID MORNING. TEMPS WARM THU AHEAD OF THE NEXT CLIPPER
SYSTEM DIVING TOWARD THE AREA. THERE WILL BE SOME INCREASING CLOUDS
DURING THE AFTERNOON...BUT NO PRECIP. HIGHS WILL BE 10 TO 15 DEGREES
BELOW NORMAL. LOWS THU NITE WILL BE 5 TO 10 DEGREES BELOW NORMAL.

FRIDAY...GUIDANCE DIGS ANOTHER SHORT WAVE INTO THE BASE OF THE MEAN
TROUGH ACROSS THE EASTERN CONUS. WHILE ALL THE MODELS REFLECT SOME
WEAK SURFACE DEVELOPMENT IN RESPONSE TO THIS FEATURE...WHERE THIS
OCCURS IS THE MATTER OF SOME CONTENTION. THE NAM CONTINUES TO SHOW
ITS SURFACE WAVE...AND RESULTING LIFT AND MOISTURE...FOR PRECIP TO
MOVE ACROSS MUCH OF THE AREA. HOWEVER...THE BULK OF THE OTHER
GUIDANCE HAS THE LOW FARTHER TO THE SOUTH WITH BETTER DEVELOPMENT
OCCURRING CLOSER TO THE COAST AS THE LOW MOVES NE. THERE IS DECENT
AGREEMENT ON SOME MOUNTAIN SNOW DEVELOPING...SO HAVE GONE WITH
CHANCE POP THERE...AND A BRIEF SLIGHT CHANCE POP ELSEWHERE. COULD
SEE SOME LOW END ACCUMS ACROSS THE MTNS...WITH MAINLY RAIN
ELSEWHERE. SOME NW FLOW SNOW WILL LINGER FRI NITE. HIGHS FRI AND
LOWS FRI NITE SHUD AGAIN BE 10 TO 15 DEGREES BELOW NORMAL AND 5 TO
10 DEGREES BELOW NORMAL RESPECTIVELY. WINDS WILL BE STRONGER FRI
NITE BEHIND THE CLIPPER...POTENTIALLY TAKING HIGH ELEVATION WIND
CHILL VALUES BACK DOWN AROUND 5 BELOW.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 350 AM WEDNESDAY...FORECAST CONFIDENCE REMAINS RELATIVELY HIGH
FOR THE EARLY PART OF THE EXTENDED...THE WEEKEND...BUT RATHER LOW
FOR EARLY NEXT WEEK. A WESTERN RIDGE/EASTERN TROUGH PATTERN WILL BE
IN PLACE AT THE START OF THE PERIOD SAT. NW FLOW MOISTURE DIMINISHES
QUICKLY SAT MORNING...BRINGING AN END TO ANY NW FLOW SNOW SHOWERS.
COLD AND DRY ARCTIC HIGH PRESSURE WILL BUILD INTO THE AREA THRU THE
WEEKEND. TEMPS WILL BE QUITE COLD WITH HIGHS DROPPING TO READINGS
NEAR THE NORMAL LOWS ON SUNDAY. LOWS WILL BE 15 TO 20 DEGREES BELOW
NORMAL SAT NITE. ALTHOUGH THE WINDS WILL HAVE DIMINISHED SAT NITE...
WITH THE COLD TEMPS IN PLACE...HIGH ELEVATION WIND CHILL VALUES WILL
AGAIN DROP DOWN TO AS LOW 15 BELOW.

UNCERTAINTY INCREASES IN THE FORECAST SUNDAY NIGHT INTO MONDAY AS AN
UPSTREAM TROUGH AMPLIFIES ACROSS THE MIDWEST...BUT WITH MODEL
DIFFERENCES SHOWING UP AS THE BASE OF TROUGH REACHES THE SOUTHEAST.
WARM FRONTAL MOISTURE MAY BRUSH THE SOUTHERN APPALACHIANS AHEAD OF
THIS SYSTEM LATE SUNDAY...BUT THE BEST MOISTURE AND FORCING AHEAD OF
A REINFORCING COLD FRONT WILL BE LATER SUNDAY NITE THROUGH MONDAY
NITE. THE GFS/GEFS CONTINUE TO FEATURE A MORE PROGRESSIVE TROUGH
PASSAGE INTO TUESDAY WHILE THE ECMWF REAMPLIFIES THE WAVE WEST OF THE
APPALACHIANS. THAT SAID..THE GFS HAS MORE SLY INFLOW WITH THIS
SYSTEM THAN PREVIOUS RUNS...BUT STILL NOT AS STRONG MORE MOIST AS
THE ECMWF. THIS PERMITS ANOTHER ROUND OF SOUTHEAST MOISTURE TO
DEVELOP. THERMAL PROFILES SUGGEST AN ONSET AS SNOW WITH THE COLD AND
DRY ANTECEDENT AIR SUNDAY NIGHT. SOME CHANGEOVER TO RAIN ACROSS SE
SECTIONS WILL BE POSSIBLE MONDAY AFTERNOON. THE GUIDANCE DIFFERS ON
THE STRENGTH OF ANY DEVELOPING CAD AND RESULTING SURFACE TEMPS.
THERE COULD BE ENUF WARMING THAT PRECIP OUTSIDE OF THE MTNS REMAINS
RAIN UNTIL THE FRONT PASSES...WHILE TEMPS COULD COOL ENUF FOR A
CHANGEOVER BACK TO SNOW BEFORE ENDING. THEREFORE...HAVE GONE WITH A
GUIDANCE BLEND AND A NORMAL DIURNAL TEMP PATTERN...SHOWING A MIX OR
CHANGEOVER MONDAY NITE. THERE IS GOOD AGREEMENT ON A RETURN TO NW
FLOW SNOW OVER THE MTNS INTO TUE. GIVEN THE LOW CONFIDENCE AND
UNCERTAINTY...WILL CONTINUE TO HOLD OFF ON A MENTION IN THE HWO FOR
NOW.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE EAST OF THE MTNS...VFR WITH A FEW MIDLEVEL
CLOUDS REFORMING BEFORE DAYBREAK WITH INCREASING UPPER LIFT WITHIN
CYCLONIC FLOW. WEAK LEE TROUGHING IS EXPECTED TO BACK WINDS SLIGHTLY
TO WSW AT KCLT AND THE SC SITES FOR A TIME THIS MORNING...BUT WNW
TO NW WILL PREVAIL THE REST OF THE PERIOD. EXPECTING A CU FIELD
TO DEVELOP OVER DEEP MIXED LAYER THIS AFTN WHICH WILL BRING DOWN A
FEW GUSTS. A FEW FLURRIES ARE LIKELY TO BE SEEN BUT WITH NO IMPACT.

AT KAVL AND IN THE MTNS...MOIST NW FLOW WILL CONTINUE TO PRODUCE
-SHSN IN THE HIGH TERRAIN INTO TONIGHT...OCCASIONALLY BEING SEEN AT
KAVL AS WELL. THOUGH GUIDANCE MAINLY KEEPS RESTRICTIONS ALONG THE
TENN BORDER...OBS SUGGEST OTHERWISE. WILL INCLUDE TEMPO MVFR. SNOW
IS LIKELY TO BLOW AWAY BEFORE ACCUMULATING. THE GUSTY WINDS SHOULD
SUBSIDE AROUND DAYBREAK BUT WILL RETURN AND PERSIST THROUGH MOST
OF THE DAY. FLURRIES MAY CONTINUE TODAY AS WELL BUT TAPER OFF
TONIGHT AS UPPER TROUGH AXIS MOVES FURTHER EAST OF THE MTNS.

OUTLOOK...A DEEP UPPER TROF WILL BEGIN TO LIFT NE OUT OF THE
AREA...TAPERING OFF THE NW FLOW SNOW SHOWERS AND CLEARING SKIES.
ANOTHER DISTURBANCE WILL QUICKLY CROSS THE AREA ON FRIDAY...WHICH
MAY PRODUCE A BRIEF PERIOD OF WINTRY PRECIP ACROSS THE AREA.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     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 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 7 PM EST THIS EVENING FOR GAZ010.
NC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ033-
     048>053-058-059-062-063.
     WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR NCZ033-048>052-
     058-059-062>064.
     WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST
     THURSDAY FOR NCZ033-048>052-058-059-062>064.
SC...NONE.

&&

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



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