Winter Weather in Georgia, January 18, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
248 PM EST WED JAN 17 2007

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
COMPLEX WEATHER SYSTEM SETTING UP AS UPPER JET REMAINS OVER AREA...
WHICH WILL HELP ENHANCE MOISTURE AS IT MOVES OVER FORECAST AREA FROM
THE S TONIGHT. AS HIGH PRESSURE NOSES DOWN THE E SIDE OF THE MTNS A
WEDGE HAS SET UP OVER CWA WITH DRYER...COLDER AIR NOSING DOWN FROM
THE NE. AN INVERTED SFC WAVE DEVELOPS ALONG THE COAST TONIGHT AND A
SIGNIFICANT AMOUNT OF MOISTURE MOVES OVER AREA WITH COLD TEMPS AND
STRONG ISENTROPIC LIFT AFTER MIDNIGHT. MODELS IN GOOD AGREEMENT AND
USING NOMAGRAMS AND PARTIAL THICKNESS SCHEMES EXPECT PRECIP TO START
AS SNOW/SLEET DURING LATE NIGHT HOURS...TURNING TO SLEET AND
FREEZING RAIN ACROSS THE FOOTHILLS/PIEDMONT TOWARD
DAYBREAK...CONTINUING INTO THE AFTERNOON HOURS...ESPECIALLY OVER NE
PART OF CWA. LIMITING FACTOR MAY BE QPF BUT BEST QPF ALONG SE HALF
CWA SO GOING WITH A WINTER STORM WARNING S OF I-85 CORRIDOR AND E OF
I-77 CORRIDOR FROM LATE TONIGHT THROUGH TOMORROW...AND A WINTER
WEATHER ADVISORY FOR THE REST OF THE CWA.
&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
AS LOW PRESSURE QUICKLY MOVES NE OF THE AREA THURSDAY EVENING...ANY
LINGERING PRECIPITATION ACROSS THE NC PIEDMONT WILL END DURING THE
EVENING. THE EXCEPTION WILL BE IN THE NC MOUNTAINS AFTER MIDNIGHT
WHERE SOME SNOW SHOWERS MAY DEVELOP DUE TO UPSLOPE FLOW AND A
PASSING VORT MAX. HOWEVER...ACCUMULATIONS WILL BE LIGHT AND THEY
SHOULD END BY DAYBREAK FRIDAY. HIGH PRESSURE WILL BEGIN BUILDING OVER THE
REGION ON FRIDAY. WITH DOWNSLOPING WINDS TEMPERATURES SHOULD REBOUND
BACK TO SEASONAL LEVELS...ESPECIALLY E OF THE MOUNTAINS. THE HIGH
CRESTS OVER THE AREA ON SATURDAY AND MOVES EAST SATURDAY NIGHT.
ISENTROPIC LIFT INCREASES SATURDAY NIGHT AND SUNDAY AS LOW PRESSURE
APPROACHES FROM THE WEST IN RESPONSE TO DIGGING UPPER TROUGH OVER
THE CENTRAL U.S. GOOD CHANCE THAT PRECIPITATION WILL DEVELOP DURING
THE DAY SUNDAY. FORECAST SOUNDINGS INDICATE THAT SNOW WOULD FALL IN
THE MOUNTAINS INITIALLY ON SUNDAY...WITH A MIXTURE OF SLEET/RAIN
OTHER AREAS. PARTIAL THICKNESSES AND BOUNDARY LAYER TEMPS WARM
SUNDAY AFTERNOON WHICH SUPPORTS GENERALLY RAIN UPSTATE SC AND NC
PIEDMONT...WITH A MIXTURE OF SNOW/SLEET...AND MAYBE SOME FREEZING
RAIN SUNDAY NIGHT IN THE MOUNTAINS. PRECIPITATION ENDS QUICKLY ON
MONDAY AS LOW PULLS AWAY TO THE NE. USED A BLEND OF MOS GUIDANCE
FOR TEMPERTURES...DEWPOINTS AND WINDS THROUGH SATURDAY.

GENERALLY FOLLOWED HPC GUIDANCE FOR MON-WED PERIOD WHICH BUILDS HIGH
PRESSURE OVER THE AREA BEGINNING LATE MONDAY INTO TUE...FOLLOWED BY
A GENERALLY DRY COLD FRONT LATE TUE...THAT PERHAPS TRIGGERS SOME
MOUNTAIN SNOW SHOWERS LATE TUE/TUE NIGHT. HPC AND PREVIOUS GFS
DEVELOPED ANOTHER SOUTHERN STREAM SURFACE LOW FOR WED WHICH PROMPTED
LOW CHANCE POPS FOR RAIN ACROSS SOUTHERN AREAS. LOOKS LIKE 12Z
GFS HAS BACKED OFF ON THIS SOLUTION. TEMPS WILL BE GENERALLY
BELOW SEASONAL LEVELS...EXCEPT CLOSE TO NORMAL ON TUE.

&&

.AVIATION...
MID AND HIGH CLOUDS WILL CONTINUE INCREASING AS THE UPPER JET AXIS
REMAINS OVER THE REGION...WITH LOWERING ALTOSTRATUS THROUGH THE
OUTLOOK PERIOD AS MOIST UPGLIDE DEVELOPS. 12Z MODEL RUNS BRING MVR
CIGS IN BY 09Z...LOWERING TO IFR AS PRECIP INCREASES AFTER DAYBREAK.
EXPECT PRECIP TO START AS A WINTRY MIX WHICH COULD HAVE A
SIGNIFICANT IMPACT ON VIS. STAYING WITH MVFR ATTM FOR EARLY MORNING
HOURS. MODEL SOUNDINGS SHOW SNOW AND OR SLEET MIXING WITH AND
TURNING TO FREEZING RAIN WHICH COULD LAST THROUGH THE MORNING
HOURS...EVEN WELL INTO THE AFTERNOON FOR NC PIEDMONT. E TO NE WINDS
AT 10 TO 15 KTS WILL CONTINUE THROUGH THU MORNING.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WINTER STORM WARNING FOR GAZ026-028-029 FROM 3 AM THURSDAY TO
     6 PM THURSDAY.
  ...WINTER WEATHER ADVISORY FOR GAZ010-017-018 FROM 3 AM THURSDAY
     TO 6 PM THURSDAY.
NC...WINTER WEATHER ADVISORY FOR NCZ033>035-048>055-058-059-062>067-
     501>510 FROM 3 AM THURSDAY TO 6 PM THURSDAY.
  ...WINTER STORM WARNING FOR NCZ036-037-056-057-068>072-082 FROM 3
     AM THURSDAY TO 6 PM THURSDAY.
SC...WINTER WEATHER ADVISORY FOR SCZ001>003 FROM 3 AM THURSDAY TO 6
     PM THURSDAY.
  ...WINTER STORM WARNING FOR SCZ004>014-019 FROM 3 AM THURSDAY TO
     6 PM THURSDAY.
&&

SHORT TERM...RB
LONG TERM...GABRIC
AVIATION...RB