Winter Weather in Georgia, December 30 to 31, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
705 PM EST WED DEC 30 2009

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE MID ATLANTIC COAST
THROUGH THURSDAY MORNING AS A WEAK AREA OF LOW PRESSURE MOVES
NORTHEAST FROM THE NORTHERN GULF OF MEXICO. ANOTHER LOW WILL
DEVELOPS OFF THE CAROLINAS COASTLINE ON THURSDAY AND MOVE UP THE
EAST COAST THROUGH FRIDAY. BEHIND THIS SYSTEM A COLD NORTHWEST FLOW
WILL SETTLE IN AND PERSIST ACROSS THE SOUTHERN APPALACHIANS THROUGH
THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
A POTENT SHORTWAVE WAS DEPICTED MOVING ACROSS THE ARKLATEX REGION
THIS AFTERNOON. A VORTICITY LOBE WILL EJECT NE FROM THIS FEATURE TO
REACH THE FORECAST AREA BY EVENING. THIS FORCING WILL BE ENHANCED BY
DEVELOPING UPPER LEVEL DIVERGENCE ALSO REACHING THE SRN APPALACHIANS
CIRCA 00Z. A MORE ROBUST TRAILING VORT MAX WILL THEN ARRIVE WITH THE
MAIN WAVE AND DEEPER MOISTURE BY 06Z TO PRODUCE THE STRONGEST Q
VECTOR CONVERGENCE ACROSS THE REGION FOR THE OVERNIGHT HOURS. THE
BRIEF DURATION OF THE BETTER FORCING SHOULD LIMIT QPF TO AROUND ONE
QUARTER INCH IN MOST LOCATIONS.

PRECIPITATION TYPE REMAINS THE MAIN FORECAST CHALLENGE FOR THIS
BRIEF EVENT. WET BULB PROFILES FROM THE 12Z MODEL RUNS ARE NOW MORE
INDICATIVE OF SNOW AND SLEET ACROSS MUCH OF THE MTNS. NOT MUCH OF A
WARM NOSE BECOMES APPARENT UNTIL AFTER 09Z. THUS...THE BULK OF THE
PRECIP COULD BE MORE SPLIT BETWEEN SNOW AND SLEET EARLY ACROSS THE
NC MTNS...WITH FREEZING RAIN DEVELOPING LATER IN THE NIGHT MAINLY
EAST OF THE BLUE RIDGE. SFC TEMPERATURES SHOULD WARM OVERNIGHT FOR
MUCH OF THE FORECAST AREA SINCE THE SFC HIGH OFF THE ERN SEABOARD IS
NOT IN A FAVORABLE POSITION FOR REINFORCEMENT OF THE COLD AIR.
HOWEVER...SFC WET BULBS MAY STAY NEAR THE FREEZING MARK ALONG AND
NORTH OF THE INTERSTATE 40 CORRIDOR EAST OF THE BLUE RIDGE THROUGH
DAYBREAK. THE FORECAST WILL THUS BE A MIXED BAG OF LIGHT
ACCUMULATING SNOW...SLEET AND FREEZING RAIN FOR MUCH OF THE
MOUNTAINS...WITH MINOR ICE ACCUMULATION ISSUES LATE TONIGHT IN THE
NRN FOOTHILLS AND POSSIBLY EXTREME WRN NC PIEDMONT. WILL POST A
WINTER WEATHER ADVISORY 8 PM TONIGHT THROUGH 9 AM THURSDAY FOR
THESES AREAS.

ANOTHER TROUGH WILL DIG INTO THE PLAINS ON THU TO KEEP UPPER FLOW
OUT OF THE WSW. A STRONG MID LEVEL DRY SLOT SHOULD MOVE IN FROM THE
SW AFTER 12Z. HOWEVER...LINGERING LOW LEVEL MOISTURE AND WEAK
UPGLIDE WILL PERMIT LIGHT RAIN OR DRIZZLE TO CONTINUE THROUGH MUCH
OF THE MORNING...BEFORE GRADUALLY ENDING FROM THE SW DURING THE
AFTN. TEMPS SHOULD RECOVER ABOUT A CATEGORY OVER WED MAX VALUES.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 130 PM WEDNESDAY...THE MAIN FCST CHALLENGE FOR THE SHORT TERM
WILL BE NORTHWEST FLOW SNOW CHCS AND ACCUM...ALONG WITH TEMPS AND
WINDS.

THE MAIN SETUP WILL BE THE BEGINNING OF A PROLONGED DEEP NWLY FLOW
ACRS THE RGN AS A POLAR VORTEX REMAINS BLOCKED OVR THE GREAT LAKES
AND NEW ENGLAND STATES. A SERIES OF SURGES OF LLVL CAA AND MOISTURE
WILL CRS THE RGN STARTING FRI...AS AXIS OF L/W TROF REACHES THE EAST
COAST BY 00Z SAT. MDLS IN GOOD AGREEMENT ON MAX Q-VECTOR CONVERGENCE
ARND 06Z-12Z FRI AS THE UPR DPVA CRSS THE MTNS. THE ONLY LIMITING
FACTOR FOR POPS IS LLVL FORCING...AS ISENTROPIC DOWNGLIDE WILL BEGIN
AND ANY UPSLOPE COMPONENT WILL BE FAIRLY WEAK (10-15 KTS IN THE
NAM). IN ANY CASE...LEFT A CHC POP FOR THE NC/TN BORDER
COUNTIES...AND A SLIVER ALONG SERN FRINGE OF CWA WHERE CDFNT WILL BE
IN THE VCNTY. TEMP TREND IS A BIT UNCERTAIN...AS CAA WILL ONLY
GRADUALLY INCR...WITH LINGER CLOUDINESS AND DECENT MIXING. I BUMPED
MIN TEMPS UP AND USED THE NAM FOR HOURLY T GRIDS. A SNOW LVLS MAY
ONLY DROP TO ABT 3500 FT...BUT A MIX OF SNOW/RAIN TO THE VALLEY
FLOORS IS EXPECTED BY 12Z FRI. ACCUM LOOK TO BE QUITE LGT (MAINLY
LESS THAN 1/2 IN.)

FRIDAY...LLVL CAA STRENGTHENS AS H85 FLOW VEERS TO MORE NWLY AND
INCREASES TO 35-40 KTS. SO IT SHUD BE WINDY IN THE HIGH TERRAIN AND
BREEZY ELSW. MOISTURE WILL BE ON THE DECR HWVR...AND SO SNOW SHWR
COVERAGE MAY BEGIN TO DECR BY MID AFTN. I KEPT LIKELY POPS ALONG THE
NW FLOW COUNTIES IN THE MORNING...THEN TAPERING THEM BACK DURING THE
AFTN. THIS LOOKS TO BE THE HIGHEST CHC FOR SNOW ACCUM (06Z-18Z FRI
TIME FRAME). TEMPS WILL HOLD STEADY OR DECR ACRS THE MTNS...BUT RISE
INTO THE 40S ACRS THE PIEDMONT THANKS TO DOWNSLOPE WARMING AND
DECREASING CLOUDINESS.

FRIDAY NGT AND SATURDAY...A LULL IN MOISTURE AND CAA EXPECTED FRI
EVE...ALTHO THE AMT OF SNOW SHWR ACTIVITY ALONG TN/NC BORDER IS LOW
CONFIDENCE FOR THIS TIME PERIOD. THE 12Z NAM/GFS AND 09Z SREF ARE IN
REASONABLE AGREEMENT ON TIMING OF A SECOND SURGE OF H85 CAA AND
MOISTURE ACRS THE SRN APPALACHIANS SATURDAY. I HAVE GONE AHEAD AND
BUMPED POPS BACK UP TO LOW-END CHC SAT TO SHOW A LTL INCR IN
CONFIDENCE. HWVR...ACTUAL ACCUM ARE LOW CONFIDENCE AS GREAT LAKES
CONNECTION IS POSSIBLE (BUT GUIDANCE DOES NOT SHOW MUCH QPF). MOS
SEEMS TOO WARM BOTH ON MINS AND MAXES SAT GIVEN THE DROP IN H85
TEMPS. SO I WENT CLOSER TO MODEL SMART INITS (WHICH I THINK ARE
BETTER REFLECTIONS OF THE LLVL THICKNESSES)...RESULTING TO COLDER
TEMPS. LLVL WNDS MAY BE STRONGER THAN ON FRI WITH THIS SECOND SURGE.
SO ANOTHER WINDY DAY EXPECTED SAT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 115 PM WEDNESDAY...THE GOING FCST OF A DRY BUT CHILLY SUNDAY
REMAINS ON TRACK AS CYCLONIC WNW FLOW ALOFT COVERS THE SE CONUS.
LITTLE CHANGE IN THE MEAN PATTERN IS SLATED FOR THE START OF THE
WORKWEEK...ALTHOUGH MEDIUM RANGE MODELS HINTING AT ENERGY ROTATING
THROUGH BASE OF L/WV ON MONDAY. PRETTY MUCH A PERSISTENCE FCST AS
FAR AS TEMPERATURES ARE CONCERNED...CONTINUED COLD. AFOREMENTIONED
S/WV ENERGY AND PROBABLY A PERIOD OF NW FLOW WARRANTS SNOW SHOWER
CHANCES FOR THE NC MTNS.

UPPER TROUGH TRENDING TOWARD LESS AMPLIFICATION ON TUESDAY...BUT
THE SENSIBLE WX CHANGES LITTLE. AGAIN...A PERSISTENCE FCST FOR
TEMPERATES...REMAINING WELL BELOW NORMAL AND CONTINUED DRY WITHIN
THE WNW FLOW. BOTH THE OP GFS AND ENS MEAN REAMPLIFY UPPER PATTERN...
DEEPENING THE EASTERN CONUS L/WV. DRY AND COLD CONTINENTAL AIRMASS
TO REMAIN THROUGH THE END OF THE PERIOD.

CURRENTLY FCSTG MAX TEMPS FOR ALL FOUR DAYS OF THE EXTENDED PERIOD
BELOW 40 FOR BOTH KGSP AND KCLT. FOUR OR MORE CONSECUTIVE DAYS OF
MAX TEMPS LESS THAN 40 DEG F HAS NOT OCCURRED SINCE THE WINTER OF
2000-01.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...MVFR CIGS MOVED IN A LITTLE MORE QUICKLY THAN EXPECTED.
THERE ARE A FEW LIGHT SHOWERS UPSTREAM OF THE AIRFIELD...BUT WITH
THE DRY AIRMASS IN PLACE OVER THE REGION...IT SHOULD STILL TAKE 3 TO
4 HOURS FOR THE RAIN TO MOVE IN. CIGS WILL FALL INTO THE IFR RANGE
LATER TONIGHT. THE MODEL GUIDANCE IMPLIES THAT CIGS MAY FALL INTO
THE LIFR RANGE AFTER 12 UTC...BUT I/VE HELD ON TO A SLIGHTLY MORE
OPTIMISTIC FORECAST. STILL...CIGS AND VSBYS WILL STAY DOWN THROUGH
THE DAY TOMORROW...AND DRIZZLE WILL CONTINUE AFTER THE RAIN ENDS.
WINDS WILL BE LIGHT THROUGH THE PERIOD...BUT THEY WILL GENERALLY BE
OUT OF THE NORTHEAST TONIGHT...WITH A GRADUAL SHIFT TO THE SOUTH OR
SOUTHEAST BY LATE THU MORNING.

AT KAVL...MVFR CIGS HAVE ALREADY MOVED ACROSS THE AIRFIELD. IT WILL
STILL TAKE THE PCPN 2 TO 3 HOURS TO MAKE IT AS FAR NORTH AS KAVL AS
THERE IS PLENTY OF DRY LLVL AIR IN PLACE. A MIX OF RAIN AND SLEET
STILL LOOKS LIKE THE MAIN PCPN TYPE...THOUGH SOME SNOW EARLY AND
FREEZING RAIN A BIT LATER TONIGHT IS STILL POSSIBLE. I/LL TRY TO
STAY ON TOP OF P-TYPE UPDATES. CIGS WILL FALL INTO THE IFR RANGE
LATE TONIGHT...AND SHOULD STAY THERE OR EVEN IN THE LIFR RANGE
THROUGH THE DAY ON THU...WITH SIMILAR FLIGHT CAT RESTRICTIONS IN
FOG. WINDS WILL BE LIGHT OUT OF THE SOUTH THROUGH THE PERIOD...
THOUGH THEY MAY TURN OUT OF THE NORTH LATE IN THE PERIOD TOMORROW.

ELSEWHERE...MVFR CIGS COVERED ALL THE REMAINING TAF SITES AT
ISSUANCE TIME. RAIN WILL SPREAD FROM SOUTHWEST TO NORTHEAST ACROSS
THE REGION OVER THE NEXT 3 TO 5 HOURS. A FEW PELLETS OF SLEET ARE
POSSIBLE...BUT THAT/S ABOUT IT. CIGS WILL FALL INTO THE IFR RANGE
LATER TONIGHT...AND MAY HIT LIFR AFTER 12 UTC TMRW. CIGS AND VSBYS
WILL REMAIN LOW THROUGH THE DAY...THOUGH THE RAIN WILL TAPER OFF TO
DRIZZLE EARLY IN THE DAY. WINDS WILL BE LIGHT...BUT GENERALLY OUT OF
THE NE TONIGHT...VEERING AROUND TO THE SOUTH LATE IN THE MORNING
TMRW.

OUTLOOK...NORTHWEST FLOW MOISTURE WILL CONTINUE THROUGH FRI. VFR
CONDITIONS WILL RETURN OUTSIDE OF THE MOUNTAINS...BUT MVFR CIGS
ALONG WITH VICINITY SNOW SHOWERS WILL BE POSSIBLE AT KAVL. GUSTY NW
WINDS ALONG WITH VFR CONDITIONS ARE EXPECTED THROUGH THE WEEKEND.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WINTER WEATHER ADVISORY UNTIL 9 AM EST THURSDAY FOR NCZ033-035-
     048>053-058-059-062>065-501>507-509.
SC...NONE.

&&

SYNOPSIS...BSH
NEAR TERM...HG
SHORT TERM...ARK
LONG TERM...CSH
AVIATION...MCAVOY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
337 PM EST WED DEC 30 2009

NCZ033-035-048>053-058-059-062>065-501>507-509-312045-
AVERY-ALEXANDER-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-
GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-
GREATER BURKE-MCDOWELL MOUNTAINS-EASTERN MCDOWELL-
RUTHERFORD MOUNTAINS-POLK MOUNTAINS-
337 PM EST WED DEC 30 2009

...WINTER WEATHER ADVISORY IN EFFECT FROM 8 PM THIS EVENING TO 9 AM
EST THURSDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

ACCUMULATING SNOW IS EXPECTED IN THE NORTH CAROLINA MOUNTAINS
LATE THURSDAY NIGHT THROUGH FRIDAY AFTERNOON...AND AGAIN ON
SATURDAY DUE TO MOIST NORTHWEST FLOW. AT THIS TIME IT APPEARS THAT
ONE TO TWO INCHES MAY FALL ALONG THE TENNESSEE BORDER...WITH
LIGHTER AMOUNTS NEAR THE BLUE RIDGE BY FRIDAY EVENING. THEN AN
ADDITIONAL LIGHT ACCUMULATION IS POSSIBLE ON SATURDAY. ALSO...FROM
MIDDAY FRIDAY THROUGH SATURDAY AFTERNOON...WINDY CONDITIONS ARE
EXPECTED ACROSS THE HIGH TERRAIN...WITH GUSTS IN THE 35 TO 45 MPH
RANGE POSSIBLE AT TIMES.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SNOW AND ICE ACCUMULATIONS
TO THE NATIONAL WEATHER SERVICE.

GAZ010-017-018-026-028-029-NCZ036-037-056-057-068>072-082-508-510-
SCZ001>014-019-312045-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-IREDELL-DAVIE-CATAWBA-
ROWAN-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
GREATER RUTHERFORD-EASTERN POLK-OCONEE MOUNTAINS-PICKENS MOUNTAINS-
GREENVILLE MOUNTAINS-GREATER OCONEE-GREATER PICKENS-
GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-ANDERSON-ABBEVILLE-
LAURENS-UNION SC-CHESTER-GREENWOOD-
337 PM EST WED DEC 30 2009

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

ARK