Wind Chill Advisory 3, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
253 AM EST SUN DEC 21 2008

.SYNOPSIS...
A COLD FRONT WILL MOVE EAST OF THE FORECAST AREA BY TONIGHT AS HIGH
PRESSURE BEGINS TO BUILD IN FROM THE WEST. THIS HIGH WILL THEN MOVE
ACROSS THE REGION AND OFF THE EAST COAST THROUGH TUESDAY AS ANOTHER
COLD FRONT APPROACHES FROM THE WEST FOR THE MIDDLE OF THE WEEK.
ANOTHER UNSEASONABLY WARM AND WET PATTERN WILL SET UP ACROSS THE
SOUTHEAST REGION WEDNESDAY THROUGH THE END OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AREA RADARS SHOW PREFRONTAL BAND OF PRECIP MOVING STEADILY EASTWARD
EARLY THIS MORNING. EXTRAPOLATION OF THE BACK END OF THE PRECIP...
WHICH IS ESSENTIALLY THE SURFACE FRONT...WILL PUT IT OVER THE
EASTERN PART OF THE FORECAST AREA AT THE START OF THE TODAY PERIOD.
THIS WILL REQUIRE KEEPING A HIGH POP ON THE EASTERN BORDER AND THE
CLT METRO AREA TO START WITH...BUT A QUICK END SHOULD BE EXPECTED BY
MID MORNING EVERYWHERE BUT THE TN BORDER ZONES. LEFTOVER LOW LEVEL
MOISTURE WILL BE FORCED UP THE W SIDE OF THE MTNS FOR A FEW HOURS
UNTIL NOON OR SO...WHICH MEANS A LOW CHANCE POP WILL BE MAINTAINED
OVER THE NRN MTNS. SNOW LEVELS WILL DROP QUICKLY THIS MORNING AS THE
COLD ADVECTION STRENGTHENS BEHIND THE FRONT SUCH THAT ANYTHING THAT
FALLS AFTER 15Z SHOULD BE SNOW. MOISTURE PULLS OUT QUICKLY THOUGH...
SO NO SIGNIFICANT ACCUMULATION IS EXPECTED. HIGH TEMPS WILL DEPEND
MAINLY ON THE POSITION OF THE COLD FRONT AT THE BEGINNING OF THE
PERIOD...BECAUSE FROM MIDDAY ONWARD THE COLD ADVECTION WILL BEGIN TO
DRIVE TEMPS DOWN...PARTICULARLY OVER THE MTNS AND FOOTHILLS.

THE MAIN PROBLEM FOR TODAY WILL BE THE WIND. RELATIVELY STRONG GUSTS
SHOULD MIX DOWN THIS MORNING IMMEDIATELY BEHIND THE FRONT TO THE
POINT WHERE A LAKE WIND ADVISORY WOULD BE WARRANTED. THERE MAY VERY
WELL BE A RELATIVE LULL IN THE AFTERNOON BEFORE WINDS STRENGTHEN
AGAIN LATE IN THE AFTERNOON...BUT THINK IT WOULD BE TOO CONFUSING TO
HAVE A BREAK IN ANY ADVISORY DURING THE MIDDLE PART OF THE DAY.
THUS...WILL ISSUE THE LAKE WIND ADVISORY BEGINNING AT 6 AM AND
RUNNING INTO TONIGHT. WILL JUMP RIGHT TO A WIND ADVISORY FROM THE
FRENCH BROAD VALLEY NORTHWARD WITH THE ANTICIPATION OF VERY STRONG
GUSTS BEGINNING IN THE LATE AFTERNOON...RATHER THAN RISK CONFUSION
WITH HAVING A LAKE WIND ADVISORY TODAY THAT TURNS INTO A REGULAR
WIND ADVISORY TONIGHT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 230 AM SUNDAY...STOUT NW WINDS WILL GRADUALLY DIMINISH
OVERNIGHT AS MODIFIED ARCTIC AIRMASS ADVECTS INTO THE REGION. THE
COMBINATION OF WIND AND COLD WILL GIVE RISE TO WIDESPREAD MTN
WIND CHILLS BELOW ZERO INTO EARLY MONDAY MORNING. SFC RIDGING WILL
CONTINUE TO BUILD EAST THRU MONDAY AND LOOSENING PRESSURE GRADIENT.
WITH COLD AIRMASS IN PLACE EVEN FULL SUNSHINE WILL STRUGGLE TO WARM
THE LLVL AIRMASS...AND MAX TEMPS ARE EXPECTED TO BE AROUND 12-16 DEG
F BELOW NORMAL. THE ONSET OF A MODIFYING AIRMASS IS SLATED FOR
TUESDAY AS RETURN FLOW INCREASES. THE INFLUX OF HIGHER LVL MOISTURE
WILL FILTER SUNSHINE WITH MAX TEMPS ON TRACK TO BE LESS CHILLY...BUT
STILL A COUPLE OF CATEGORIES BELOW NORMAL.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 215 AM SUNDAY...THERE JUST ISNT A WHOLE LOT OF CONFIDENCE IN
THE MEDIUM RANGE FORECAST. THE LATEST RUNS OF THE GFS AND ECMWF ARE
AT ODDS WITH THE FRONTAL BOUNDARY THAT MOVES INTO THE AREA ON
WEDNESDAY AND ITS EVENTUAL EVOLUTION. THE GFS FAVORS A SOLUTION THAT
BRINGS THE FRONT INTO THE FA WEDNESDAY...STALLING IT OUT AND LAYING
IT OVER THE REGION FOR A COUPLE OF DAYS BEFORE ANOTHER FRONT
APPROACHES LATER IN THE WEEK. THIS SOLUTION WOULD SUPPORT SOME
DEGREE OF POPS AND LIGHT QPF PRETTY MUCH EVERY PERIOD TUESDAY NIGHT
THROUGH SATURDAY. ON THE OTHER HAND...THE NEW ECMWF JUST CAME IN
SHOWING THE FRONT MOVING EAST OF THE FA ON THURSDAY BEFORE RETURN
FLOW LIFTS THE REMNANT BOUNDARY BACK NORTH AS THE NEXT SYSTEM
APPROACHES ON SATURDAY. I HAVE PRIMARILY FOLLOWED A BLEND OF THE GFS
AND HPC GUIDANCE...WHICH FAVORS THE MORE ACTIVE AND WETTER SOLUTION.
THE FORECAST WILL ADVERTISE HIGH END CHC POPS WEDNESDAY AND
WEDNESDAY NIGHT...TAPERING OFF TO LOWER CHC POPS AND THEN SLT CHC
POPS BY SATURDAY TO ACCOUNT FOR THE LACK OF CONFIDENCE IN THE
EVENTUAL PLACEMENT OF THE FRONT. ONE THING THE TWO MODELS DO AGREE ON
HOWEVER IS THE MILD TEMPERATURES. DAYTIME HIGHS WILL RUN A GOOD 10
TO 12 DEGREES ABOVE CLIMO AND LOWS WILL BE SIMILARLY WARM.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
JUST ABOUT SIX MORE HOURS UNTIL WE FINALLY WRAP UP WHAT HAS BEEN A
DIFFICULT WEEK FOR AVIATION CONCERNS. IN THE MEAN TIME...WE CONTINUE
TO HERD CATS AND NAIL JELLO TO THE WALL...BECAUSE OF HIGHLY VARIABLE
CEILING AND VISIBILITY ACROSS THE WESTERN CAROLINAS. THE THINKING IS
THAT CEILING/VIS SHOULD CONSOLIDATE INTO A PREVAILING MVFR CONDITION
WITH TEMPORARY IFR VISIBILITY ONCE THE MAIN FRONTAL PRECIP BAND
WORKS ITS WAY ACROSS THE TAF SITES OVER THE NEXT HOUR OR TWO...AND
THAT SHOULD CONTINUE THROUGH ABOUT SUNRISE WHEN THE BACK EDGE OF THE
FRONTAL ZONE SWEEPS IN FROM THE WEST.

AT KCLT...THE IFR CEILING SHOULD MOVE OUT TO THE NORTHEAST BY 07Z OR
SO...LEAVING THEM IN AND OUT OF AN MVFR CEILING PRIOR TO THE ARRIVAL
OF THE FRONTAL PRECIP.

THE PASSAGE OF THE FRONT WILL OCCUR IN THE 10Z TO 14Z TIME FRAME
WEST TO EAST AND MAY BE ACCOMPANIED BY A SHIFT TO A MORE WESTERLY
WIND AND SOME MVFR CEILINGS. HOWEVER...BY MID MORNING THE DEEPER
MOISTURE SHOULD BE WELL TO OUR EAST LEAVING ONLY A FEW STRATOCU. THE
WIND BECOMES THE MAIN FACTOR THEN...WITH STRONG GUSTY WNW WIND
THROUGH THE END OF THE TAF PERIOD. MIXING IS ACTUALLY A BIT DEEPER
DURING EARLY TO MID SUNDAY EVENING SO THAT MIGHT BE THE GUSTIEST
PERIOD. EITHER WAY...AT KCLT THE WIND SHOULD STAY N OF W FROM LATE
MORNING ONWARD. ONLY KAND WILL HAVE A WIND THAT IS MORE W AND NW
BECAUSE OF FLOW AROUND THE MTNS.

OUTLOOK...DRY HIGH PRESSURE WITH VFR CONDITIONS EXPECTED FROM SUNDAY
NIGHT THRU TUESDAY. COLD FRONT APPROACHES TUE NIGHT-WED WITH CHANCE
SHOWERS AND CIG/VSBY RESTRICTIONS.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...LAKE WIND ADVISORY UNTIL 6 AM EST MONDAY FOR GAZ010-017-018-
     026-028-029.
NC...WIND ADVISORY UNTIL 6 AM EST MONDAY FOR NCZ033-048>050-053-065-
     501-503-505-507.
     LAKE WIND ADVISORY UNTIL 6 AM EST MONDAY FOR NCZ035>037-051-
     052-056>059-062>064-068>072-082-502-504-506-508>510.
     WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST MONDAY
     FOR NCZ033-048>053-058-059-062>065.
SC...LAKE WIND ADVISORY UNTIL 6 AM EST MONDAY FOR SCZ001>014-019.

&&

SYNOPSIS...BSH
NEAR TERM...PM
SHORT TERM...CSH
LONG TERM...BSH
AVIATION...PM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
326 PM EST SAT DEC 20 2008

NCZ033-048>053-058-059-062>065-212030-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
326 PM EST SAT DEC 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AS RAINFALL BECOMES WIDESPREAD ACROSS THE AREA TONIGHT...ISOLATED
THUNDERSTORMS MAY ACCOMPANY THE RAIN. IT IS POSSIBLE THAT
LOCALIZED DAMAGING WIND GUSTS WILL DEVELOP WITH ANY STRONGER
STORMS TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

INCREASINGLY WINDY AND COLDER WEATHER IS ON TAP FOR SUNDAY AND
SUNDAY NIGHT IN THE WAKE OF A STRONG COLD FRONT. WIND GUSTS ARE
EXPECTED TO INCREASE TO 40 OR 50 MPH SUNDAY AFTERNOON OR EVENING.
SO LOCALIZED WIND DAMAGE MAY OCCUR. WIND CHILL INDEX VALUES ARE
LIKELY TO FALL INTO THE 5 TO 10 BELOW ZERO RANGE SUNDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

NONE.

NCZ035>037-056-057-501>506-212030-
ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-CALDWELL MOUNTAINS-
GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-MCDOWELL MOUNTAINS-
EASTERN MCDOWELL-
326 PM EST SAT DEC 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PIEDMONT NORTH CAROLINA AND
WESTERN NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.
AS RAINFALL INCREASES OVERNIGHT...SOME ISOLATED THUNDERSTORMS MAY
OCCUR.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

STRONG WIND GUSTS COULD DEVELOP ACROSS THE REGION SUNDAY AFTERNOON
OR EVENING IN THE WAKE OF A SHARP COLD FRONT. WIND GUSTS OF 35 TO
45 MPH MAY OCCUR. MUCH COLDER TEMPERATURES ARE ON TAP FOR SUNDAY
NIGHT WITH LOWS IN THE TEENS AND WIND CHILLS IN THE SINGLE DIGITS.

.SPOTTER INFORMATION STATEMENT...

NONE.

GAZ010-017-018-026-028-029-NCZ068>072-082-507>510-SCZ001>014-019-
212030-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-CLEVELAND-LINCOLN-
GASTON-MECKLENBURG-CABARRUS-UNION NC-RUTHERFORD MOUNTAINS-
GREATER RUTHERFORD-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
326 PM EST SAT DEC 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AS RAINFALL BECOMES WIDESPREAD ACROSS THE AREA INTO
TONIGHT...ISOLATED THUNDERSTORMS MAY ACCOMPANY THE RAIN. IT IS
POSSIBLE THAT LOCALIZED DAMAGING WIND GUSTS WILL DEVELOP WITH ANY
STRONGER STORMS TONIGHT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

STRONG WIND GUSTS ARE LIKLEY TO DEVELOP ACROSS THE REGION SUNDAY
AFTERNOON OR EVENING IN THE WAKE OF A SHARP COLD FRONT. MUCH
COLDER TEMPERATURES WILL ARRIVE LATE SUNDAY WITH TEMPERATURES
FALLING WELL BELOW FREEZING SUNDAY NIGHT AND WIND CHILLS TO AROUND
10 ABOVE.

.SPOTTER INFORMATION STATEMENT...

NONE.