Winter Storm in Georgia, February 1, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
300 AM EST THU FEB 1 2007

.SHORT TERM /TODAY THROUGH FRIDAY/...
RADAR/SATELLITE/SFC OBS SHOW RAPID PROGRESSION OF PRECIP MOVING
ACROSS N GA EARLY THIS MORNING AS LOW LEVEL UPGLIDE/FRONTOGENESIS
STRENGTHENS FROM THE SW. THE LEADING EDGE OF THE PRECIP WILL
CONTINUE TO HAVE TROUBLE WORKING INTO THE VERY DRY MID LEVELS AND
MUCH OF IT WILL GO TO MOISTENING THE COLUMN. THAT SAID...LATEST SFC
OBS SHOW LIGHT SNOW FALLING AT KGVL...SO IT WILL NOT BE LONG BEFORE
THIS ARRIVES FROM THE W. ALL IN ALL...NOT MUCH HAS CHANGED FROM
EARLIER THINKING IN TERMS OF TIMING OF PRECIP ONSET AND THE
CATEGORICAL POP. THE MODELS ALL SHOW PLENTY OF FORCING AND GENERATE
PLENTY OF PRECIP TO SUPPORT THE WARNING WE HAVE IN PLACE...SO NO
CHANGES THERE EITHER.

WHAT HAS CHANGED A BIT IS THE PROGRESSION OF PRECIP TYPES. THE
MODELS IN GENERAL HAVE COME IN A BIT COLDER WITH MID LEVEL
THICKNESSES...AND IN PARTICULAR THE NAM IS MUCH COLDER. COMPARED TO
THE 06Z SOUNDING AT GSO...THE GFS SEEMS TO BE VERIFYING A BIT BETTER
IN THAT REGARD. IN GENERAL...THE GFS WAS FOLLOWED FOR THE NEAR TERM
FOR THAT REASON AND BECAUSE IT SEEMS TO HAVE A BETTER HANDLE ON
SURFACE TEMPS. AS PRECIP MOVES IN...MODEL SOUNDINGS QUICKLY BECOME
ISOTHERMAL...SUGGESTING WE SHOULD SEE A PERIOD OF SEVERAL HOURS
WHERE THE PRECIP WILL FALL PRIMARILY AS SNOW NEARLY EVERYWHERE
ACROSS THE CWA. IT COULD FALL AT THE RATE OF NEARLY AN INCH PER HOUR
IN THE AREA S OF I-40. WITH THIS IN MIND...SNOWFALL TOTALS WILL BE
REVISED UPWARD. THE CHANGEOVER TO SLEET AND FREEZING RAIN MIGHT NOT
HAPPEN UNTIL THE MIDDLE PART OF THE DAY OR EARLY AFTERNOON...BUT
SHOULD HAPPEN EVENTUALLY BY MID AFTERNOON ACROSS ALL BUT THE MTNS.
THE MODELS SHOW THE FIRST ROUND OF PRECIP EXITING DURING THE
MID/LATE AFTERNOON...BUT THERE SHOULD BE ENOUGH LOW LEVEL UPGLIDE TO
MAINTAIN AT LEAST SOME LIGHT PRECIP/FREEZING DRIZZLE THROUGH SUNSET.

SECOND WAVE OF PCPN SLATED FOR THE TONIGHT PERIOD WITH AN ADDITIONAL
0.20 TO 0.40 LIQUID PROBABLE. AT THIS JUNCTURE NOT HOLDING OUT MUCH
HOPE FOR GREATER THAN 32 DEG F WET BULB TEMPS TO MAKE MUCH HEADWAY
TOWARD THE HEART OF WEAKENING IN-SITU WEDGE. PLAN ON CONTINUING TO
CARRY FRZA AS THE PRIMARY WEATHER TYPE ROUGHLY NORTH OF AN
INTERSTATE 85/26 BOUNDARY. DEEPER MOISTURE IS PROGGED TO MOVE
DOWNSTREAM OF THE CWFA BEFORE SUNRISE FRIDAY WITH THE LLVL FLOW
BECOMING INCREASINGLY WESTERLY. WITH THE LATE NIGHT ENDING OF PCPN
CHANCES...LINGERING WEAK SFC FLOW AND NEAR TO JUST BELOW FREEZING
TEMPS...TRAVEL DURING THE FRIDAY MORNING COMMUTE MAY BE HAMPERED.

DESPITE NEBULOUS SFC PATTERN...WILL GO WITH DIMINISHING CLOUDS ON
FRIDAY WITH THE EXCEPTION BEING THE WESTERN NC MTNS WHERE A DEGREE
OF UPSLOPE FLOW AND CAA IS FCST. WILL CONTINUE TO MENTION CHANCE OF
RAIN AND SNOW SHOWERS ACROSS THIS REGION.
&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
GOING TOKEN SLIGHT CHANCE POP FOR THE WESTERN NC MTNS WILL BE
MAINTAINED FRIDAY NIGHT WITHIN THE WANING UPSLOPE MOISTURE AND
WESTERLY FLOW. IT IS INTERESTING TO NOTE THE DIFFERENCES IN THE
LARGE SCALE PATTERN ON BOTH THE 01/00 UTC RUNS OF THE OP GFS/NAM
WITH THE NAM FOR SAT/SAT NITE FCSTG A CONSIDERABLY FURTHER WEST
POSITION TO THE AXIS OF THE L/WV TROUGH AND CONVERSELY...RETURNS
CONSIDERABLE MOISTURE INTO THE CWFA NORTH OF Q-STRY BNDRY. THERE
CERTAINLY IS ENOUGH SUPPORT FROM THE 00 UTC GFS ENS...12 UTC ECMWF
AND 00 UTC UKMET TO CONTINUE TO KEEP THE WEEKEND FCST DRY AND CHILLY
WITH THE MEAN UPPER TROUGH POSITION NEAR THE GSP LONGITUDE AND
MOISTURE SUPPRESSED WELL TO OUR SOUTH. MEAN PATTERN LOOKS TO CHANGE
LITTLE MONDAY THROUGH WEDNESDAY...FEATURING L/WV LINGERING ACROSS
THE EASTERN U.S. CLIPPER COULD BRING SOME SNOW SHOWERS TO THE MTNS
SUNDAY NIGHT AND/OR MONDAY...BUT MOST NOTABLE ASPECT OF THIS PATTERN
WILL BE THE ARCTIC AIRMASS SETTLING OVER THE CWFA IN THE WAKE OF
THIS FEATURE TUESDAY AND WEDNESDAY.
&&

.AVIATION /06Z-06Z/...
VFR CONDITIONS AT 06Z WILL QUICKLY DETERIORATE EARLY THIS MORNING AS
LOW LEVEL FORCING ARRIVES AND PRECIP RAPIDLY DEVELOPS. THE INITIAL
PRECIP WILL TAKE SOME TIME TO MOISTEN THE COLUMN AND WILL EVENTUALLY
REACH THE GROUND AS LIGHT SNOW/SLEET FOR A FEW HOURS WHILE VIS
REMAINS 6SM OR ABOVE AND CEILINGS LITERALLY DROP PRECIPITOUSLY. THE
PRECIP SHOULD HASTEN THE DEVELOPMENT OF INSITU COLD AIR DAMMING
WHICH WILL SHIFT SURFACE WINDS AROUND TO A NE DIRECTION. EXPECT ALL
TAF SITES TO BECOME MVFR WITH LOW CLOUDS/VIS AS INITIAL PRECIP
INTENSIFIES IN THE 11Z TO 13Z TIME FRAME...THEN DROP TO IFR WITH
SNOW DURING THE MIDDLE PART OF THE MORNING. FROM MIDDAY ONWARD...LOW
IFR CEILINGS ARE A SURE BET...THROUGH THE END OF THE TAF PERIOD. THE
TIMING OF THIS WILL BE KEYED UPON THE TRANSITION TO RAIN/FREEZING
RAIN AT ALL TAF SITES SOME TIME AFTER 15Z. IN FACT...ONCE THE LIFR
CEILING IS ESTABLISHED...IT WILL MOST LIKELY PERSIST WELL INTO
FRIDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR GAZ010-017-
     018-026-028-029.

NC...WINTER STORM WARNING UNTIL 6 AM EST FRIDAY FOR NCZ033-035>037-
     048>053-056>059-062>065-068>072-082-501>510.

SC...WINTER STORM WARNING UNTIL 6 AM EST FRIDAY FOR SCZ003-006>009.

     WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR SCZ001-002-
     004-005-010>014-019.

&&

SHORT TERM...PM/CSH
LONG TERM...CSH
AVIATION...MOORE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
404 PM EST WED JAN 31 2007

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-012115-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-
CATAWBA-ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-
TRANSYLVANIA-HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-
CABARRUS-UNION NC-CALDWELL MOUNTAINS-GREATER CALDWELL-
BURKE MOUNTAINS-GREATER BURKE-MCDOWELL MOUNTAINS-EASTERN MCDOWELL-
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-
404 PM EST WED JAN 31 2007

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

A WINTER STORM WARNING WILL START AT 4 AM THURSDAY FOR THE ENTIRE
FORECAST AREA. SNOW...POSSIBLY MIXED WITH SLEET...WILL MOVE INTO
THE REGION FROM THE SOUTHWEST BEFORE DAYBREAK.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

HEAVY ACCUMULATING SNOWFALL WILL AFFECT THE NORTH CAROLINA
MOUNTAINS AND EXTREME WESTERN FOOTHILLS DURING THE DAY ON
THURSDAY. THE PRECIPITATION WILL CHANGE TO SLEET AND FREEZING
RAIN...ESPECIALLY SOUTH OF INTERSTATE 40...THROUGH THE DAY.

NORTHEAST GEORGIA...UPSTATE SOUTH CAROLINA AND THE NORTH CAROLINA
PIEDMONT WILL LIKELY SEE LIGHTER ACCUMULATIONS OF SNOW EARLY
THURSDAY...BEFORE THE PRECIPITATION CHANGES OVER TO SLEET AND
FREEZING RAIN BY NOON. DAMAGING ACCUMULATIONS OF ICE ARE EXPECTED
ACROSS MOST OF THE AREA.

FOR ADDITIONAL DETAILS ON THE IMPENDING WINTER STORM...PLEASE SEE
THE LATEST URGENT WINTER WEATHER MESSAGE...CAEWSWGSP.

VERY COLD TEMPERATURES ARE EXPECTED TO REMAIN IN PLACE ACROSS THE
REGION THROUGH THE NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ASKED TO RELAY ANY REPORTS OF SNOW OR ICE ACCUMULATION
TO THE NATIONAL WEATHER SERVICE.

GERAPETRITIS