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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 101147
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
647 AM EST WED FEB 10 2010

.SYNOPSIS...
AS STRONG LOW PRESSURE MOVES FARTHER OFF THE COAST...THE
PRESSURE GRADIENT BETWEEN THE LOW AND THE HIGH OVER THE MISSISSIPPI
VALLEY WILL CREATE VERY WINDY CONDITIONS TODAY.  LOW PRESSURE OVER
THE GULF EARLY FRIDAY WILL BE WELL OFF THE CAROLINA COAST EARLY
SATURDAY.  AN UPPER LEVEL SYSTEM WILL QUICKLY CROSS FROM THE
NORTHWEST EARLY SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
A DEEP UPPER LOW CENTER IS TRANSLATING QUICKLY EWD INTO THE CENTRAL
APPALACHIANS EARLY THIS MORNING. THE ASSOCIATED COLD FRONT EXTENDING
S OF THIS FEATURE IS SCOURING LOW LEVEL MOISTURE ACROSS THE
PIEDMONT...WITH STRONG COLD ADVECTION ALREADY STARTING ACROSS MUCH
OF THE CWFA. THE TWO MAIN FORECAST ISSUES ARE SNOW AND WIND.

FIRST THE SNOW. IN ADDITION TO STEADILY IMPROVING NW FLOW MOISTURE
TODAY...WITH A DECENT GREAT LAKES CONNECTION...UPPER JET DIVERGENCE
WILL ALSO TRAVERSE WRN NC. SNOW SHOWERS WILL INCREASE IN THE TYPICAL
NW FLOW PRONE LOCATIONS...BUT VERY STRONG FLOW ALONG WITH THE UPPER
JET SUPPORT COULD PUSH ISOLATED TO SCATTERED SNOW SHOWERS EWD INTO
THE PIEDMONT ALONG INTERSTATE 40 TODAY. ANY ACCUMULATING SNOWFALL
SHOULD BE CONTAINED MAINLY WITHIN THE CURRENT WINTER STORM WARNING
AREA...AS NW FLOW MOISTURE DEEPENS ALONG THE SPINE OF THE SRN
APPALACHIANS AND CONTINUES INTO TONIGHT. ALTHOUGH MODEL QPF IS NOT
TREMENDOUS WITH THIS EVENT...THE STRENGTH AND DEPTH OF THE NW FLOW
MOISTURE...ALONG WITH INSTABILITY IN THE FLOW...SHOULD PRODUCE STORM
TOTAL SNOWFALL OF 5 OR 6 INCHES NEAR THE TN BORDER TODAY THROUGH
TONIGHT...WITH 2 TO 3 INCHES IN EXTREME SE PARTS OF THE WARNING AREA.

WINDS WILL BE THE BIGGER ISSUE FOR MUCH OF THE AREA. DECENT MODEL
CONSENSUS EXISTS ON 850 MB WIND SPEEDS EXCEEDING 50 KT BY 12Z THIS
MORNING...WITH H85 MAXIMUM FLOW IN THE COLD ADVECTION POSSIBLY
REACHING 60 KT LATER THIS AFTERNOON. MODEL TIME HEIGHTS SHOW
TREMENDOUS DOWNWARD OMEGA ALONG THE BLUE RIDGE TODAY...POSSIBLY
ENHANCED BY FRONTOGENESIS DUE TO DOWNSLOPE WARMING JUST EAST OF THE
ESCARPMENT. WITH 70 KT WINDS AT 700 MB BY 18Z TODAY...AND 100 KT AT
500 MB...DOWNWARD MOMENTUM TRANSPORT WILL BE FANTASTIC DURING PEAK
MIXING. WILL CONTINUE TO ADDRESS THE HIGH WIND THREAT IN THE WINTER
STORM WARNING WHERE APPLICABLE. ELSEWHERE...HAVE ALREADY UPGRADED
THE HIGH WIND WATCH TO A WARNING FROM TOCCOA TO ANDERSON TO
SPARTANBURG TO ROCK HILL...WITH A TIER OF ADVISORY WINDS ACROSS THE
EXTREME SRN PIEDMONT. DAMAGING WIND GUSTS IN THE WARNING AREA COULD
BE REMINISCENT OF MARCH 7 2004...WITH WIDESPREAD DOWNED TREES AND
POWER LINES...ESPECIALLY ACROSS WRN NC. WILL ALSO MENTION SOME MINUS
5 C WIND CHILL VALUES AT HIGHER ELEVATIONS FOR BOTH THIS MORNING AND
EARLY THURSDAY MORNING IN THE WARNING PRODUCTS.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 AM WEDNESDAY...MOIST NORTHWEST FLOW WILL OVERLAP INTO THE
DAYTIME HOURS ON THURSDAY. SCT SHSN SHOULD CONTINUE TO DEVELOP OVER
THE WESTERN SLOPES OF THE NRN NC MTNS THURSDAY MORNING. DRY HIGH
PRESSURE WILL MOVE EAST THE CENTRAL MISSISSIPPI RIVER THURSDAY
AFTERNOON. BY 18Z...FORECAST SOUNDINGS INDICATE DEEP DRYING
ALOFT...WITH ENOUGH LLVL MOISTURE TO SUPPORT SOME UPSLOPE
CLOUDINESS. MTN WINDS WILL ALSO REMAIN QUITE GUSTY DURING THE
MORNING HOURS. WINDS WILL WEAKEN ACROSS THE FORECAST AREA AS HIGH
PRESSURE APPROACHES DURING THE AFTERNOON. NORTHWEST FLOW WILL KEEP LLVL
TEMPERATURES AND THICKNESSES FAIRLY CHILLY ACROSS THE WESTERN
CAROLINAS THURSDAY AFTERNOON. HOWEVER...H85 TEMPS WILL TREND WARMER
THROUGH THE DAY. GIVEN SOME REBOUND IN THE THERMAL PROFILE AND
INCREASE INSOLATION...TEMPERATURES WILL GENERALLY WARM 5 DEGREES
ABOVE TODAY/S FORECAST VALUES. REMAINING NEARLY 10 DEGREES BELOW
NORMAL.

SKY COVER WILL REMAIN FAIRLY THIN THURSDAY EVENING...HIGH CLOUDS
WILL ADVANCE WEST TO EAST ACROSS THE CWA DURING THE PRE DAWN HOURS.
LIGHT WINDS AND COOL LLVL THICKNESS...TEMPS SHOULD FALL INTO THE 20S
ACROSS THE FORECAST AREA BY FRI MORNING. CLOUDS WILL STEADILY
THICKEN AND LOWER THROUGH THE DAYTIME ON FRIDAY. THE TIMING OF THE
CLOUD COVER WILL KEEP TEMPS FROM WARMING STEADILY FROM LOW MORNING
TEMPERATURES. I WILL FORECAST VALUES ONLY A DEGREE OR SO FROM
THURSDAY/S VALUES.

HPC PREFERS A BLEND OF THE ECMWF AND UKMET FRI NIGHT AND SAT. BY THIS
TIME...A CLOSED LOW THAT ORIGINATED OVER SOUTHERN CA AND THE DESERT
SW WILL OPEN TO A S/W AND TRACK ACROSS THE DEEP SOUTH. THE CENTER OF
THE SFC LOW IS EXPECTED TO TRACK ACROSS THE NORTHERN SHORE OF GULF
AND ACROSS THE FL. THE ECMWF INDICATES THAT A PERIOD OF Q VECTOR
CONVERGENCE WILL FORM WELL NORTH OF THE SFC LOW AND WILL MOVE WEST
TO EAST ACROSS NE GA AND THE SC UPSTATE LATE FRIDAY EVENING INTO THE
EARLY MORNING HOURS OF SAT. MODEL QPF IS LESS THAN A .10 OF AN
INCH...BUT COMPARES WELL WITH THE PLACEMENT OF
NAM...UKMET...GEM...SREF PLUME QPF. I WILL FAVOR CHC POPS MAINLY
ACROSS NE GA...SC UPSTATE...AND NC ZONES SOUTH OF I-40. TEMPERATURES
WILL GENERALLY REMAIN AT OR BELOW FREEZING DURING THE QPF...YIELDING
A TOTAL -SN EVENT. LITTLE TO NO ACCUMULATION EXPECTED. THE LOW AND
UPPER FORCING WILL DEPART AFTER SUNRISE SATURDAY...I WILL END POPS
QUICKLY DURING THE MORNING. HIGH TEMPERATURES SHOULD REMAIN AROUND
10 DEGREES BELOW NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 250 AM WEDNESDAY...STARTING 00Z SUNDAY WILL BE BETWEEN SYSTEMS
AND NOTHING GOING ON IN THE EARLY SATURDAY NIGHT TIME.  GOING INTO
SUNDAY MORNING...BOTH THE GFS AND ECMWF HAVE A CUT OFF 500MB LOW
ROUGHLY OVER ILLINOIS WITH THE ECMWF BEING A BIT FASTER.  BOTH OF
THESE MODELS ARE VIGOROUS WITH THE PRECIP SHIELD ADVANCING ACROSS
TENNESSEE.  IN COMPARISON TO THE GEM...WHICH ROTATES THIS CUT OFF
LOW FEATURE FROM KANSAS TO ARKANSAS LATER...00Z MONDAY TO 12Z
MONDAY...AND THEN FADES IT OUT NEAR OUR AREA BY 00Z TUESDAY.
STICKING WITH A COMBINATION OF GFS AND ECMWF...ONCE THE CUT OFF LOW
IS PASSING NEAR OUR AREA WHICH WOULD BE SUNDAY NIGHT...MOISTURE WILL
TEND TO LINGER ALONG THE WESTERN SLOPES OF THE APPALACHIANS TO
AROUND 00Z TUESDAY AND POSSIBLY EVEN LATER INTO MONDAY NIGHT.  UPPER
TROFINESS CONTINUES INTO MID WEEK...BUT SURFACE HIGH PRESSURE WILL
PREVAIL TO END THE SEVEN DAY FORECAST.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AT KCLT...NW WINDS HAVE ALREADY BEGUN TO GUST AT TAF TIME THIS
MORNING. GUSTS SHOULD INCREASE RAPIDLY TO 35 KT THROUGH 15Z...THEN
LIKELY EXCEED 40 KT AT TIMES THROUGH THE AFTERNOON AND EARLY EVENING
HOURS. ISOLATED GUSTS UP TO 50 KT WILL BE POSSIBLE DURING PEAK
MIXING LATE THIS AFTN. WINDS WILL STEADILY DIMINISH OVERNIGHT. TOWER
PERSONNEL SHOULD CLOSELY MONITOR WINDS TODAY IN CASE TOWER
EVACUATIONS BECOME NECESSARY DUE TO HIGH WINDS.

AT KAVL...RETURNING NW FLOW MOISTURE BEHIND THE FRONT WILL YIELD
MAINLY VFR CIGS THROUGH THE MORNING...WITH MVFR CIGS INCREASINGLY
LIKELY THROUGH THE AFTERNOON HOURS. A SNOW SHOWER IS POSSIBLE IN THE
VICINITY. WINDS WILL BE THE MAIN ISSUE...AS GUSTS ABOVE 45 KT ARE
EXPECTED WITH PEAK MIXING FROM LATE MORNING THROUGH THE AFTERNOON
HOURS. TOWER PERSONNEL SHOULD CLOSELY MONITOR THE WIND SPEEDS TODAY
AS A SAFETY PRECAUTION. WINDS WILL DIMINISH VERY SLOWLY OVERNIGHT.

ELSEWHERE...SCATTERED STRATOCUMULUS ARE EXPECTED THROUGHOUT THE DAY
IN STRENGTHENING NW FLOW COLD ADVECTION...EXCEPT VFR CIGS ARE MORE
LIKELY AT KHKY THIS AFTERNOON. WIND GUSTS MAY APPROACH 40 KT WITH
PEAK MIXING THIS AFTERNOON. ISOLATED GUSTS OF 40 TO 50 KT BY EARLY
EVENING CANNOT BE RULED OUT...ESPECIALLY AT KHKY. TOWER PERSONNEL
SHOULD CLOSELY MONITOR THE WIND SPEEDS TODAY AS A SAFETY PRECAUTION.

OUTLOOK...WIND SPEEDS WILL DIMINISH THURSDAY AS DRIER HIGH PRES
BUILDS IN FROM THE WEST. VFR CONDITIONS SHOULD THEN CONTINUE THROUGH
THE REST OF THE OUTLOOK PERIOD.
-- End Changed Discussion --

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...HIGH WIND WARNING UNTIL 6 AM EST THURSDAY FOR GAZ010-017-018.
     WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR GAZ026-028-029.
NC...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR NCZ033-
     048>053-058-059-501-503-505.
     HIGH WIND WARNING UNTIL 6 AM EST THURSDAY FOR NCZ035>037-056-
     057-062>065-068>072-082-502-504-506>510.
SC...HIGH WIND WARNING UNTIL 6 AM EST THURSDAY FOR SCZ001>010.
     WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR SCZ011>014-019.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...NED
LONG TERM...DEO
AVIATION...HG