Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
347 AM EST MON DEC 10 2012

.SHORT TERM /TODAY THROUGH TUESDAY/...
APPROACHING SYSTEM HAS MAINTAINED A FAIRLY NARROW LINE OF CONVECTION
OVERNIGHT AS IT PRESSED OUT OF THE MISSISSIPPI VALLEY INTO THE
TENNESSEE VALLEY AND WESTERN ALABAMA. GFS...NAM AND ECMWF ALL SHOW A
STRONG LOW-LEVEL JET MOVING INTO NORTH GEORGIA THIS MORNING INTO THE
AFTERNOON WITH A PEAK OF AROUND 40-50KT OF LOW-LEVEL BULK SHEAR. THE
NAM AND ECMWF PUSH AROUND 300-500 J/KG OF CAPE INTO THE NORTHWESTERN
1/3 OF THE STATE BY MIDDAY WHILE THE GFS STRUGGLES TO GENERATE
ANYTHING EXCEEDING 100 J/KG. BASED ON FORECAST SOUNDINGS...AMPLE
CLOUD COVER AND LIFTING/WEAKENING SHORT WAVE THE MOST LIKELY
SCENARIO IS SOMEWHERE IN BETWEEN THE TWO SOLUTIONS. WE SHOULD SEE
MARGINAL INSTABILITY FOR MAINTAINING MODERATELY DEEP CONVECTION INTO
THE STATE WITH AMPLE SHEAR FOR A SLIGHT CHANCE OF SEVERE STORMS
ACROSS THE NORTHWEST LATE THIS MORNING INTO THE AFTERNOON BEFORE
INSTABILITY AND SHEAR DIMINISH. SHEAR IS LARGELY SPEED BASED WITH
ONLY A SMALL DIRECTION COMPONENT SO ISOLATED DAMAGING WIND EVENTS
ARE THE PRIMARY THREAT...ALTHOUGH AN ISOLATED TORNADO THREAT CANNOT
BE COMPLETELY RULED OUT. THIS STRONG LOW-LEVEL JET WILL ALSO BRING
WIND ADVISORY LEVEL WINDS TO THE HIGHER ELEVATION OF THE NORTH
GEORGIA MOUNTAINS...MAINLY ABOVE AROUND 1500 FEET. I HAVE ISSUED A
WIND ADVISORY FOR OUR NORTHERNMOST COUNTIES FROM LATE MORNING INTO
THE EARLY EVENING.

THE UPPER LEVEL FLOW REMAINS SOUTHWESTERLY THROUGH THE FORECAST
PERIOD AFTER THE SHORT WAVE LIFTS NORTH OF THE REGION AS THE LONG
WAVE PATTERN REMAINS FAIRLY STATIC MAINTAINING A BROAD TROUGH OVER
THE CENTRAL U.S. EVEN SO RELATIVELY STRONG COLD ADVECTION SPILLS IN
BEHIND THE FRONT TONIGHT THROUGH TUESDAY WITH NOTICEABLY COOLER
TEMPERATURES...ALTHOUGH THIS REALLY ONLY KNOCKS US BACK CLOSER TO
SEASONAL NORMALS. A WEAK IMPULSE IN THE SOUTHWEST FLOW SPREADS SOME
MOISTURE BACK NORTH TUESDAY FOR A SLIGHT CHANCE OF SHOWERS ACROSS
THE SOUTHERN REACHES OF CENTRAL GEORGIA.

20

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
FRONT REMAINS POSITIONED ACROSS SOUTHEAST GEORGIA TUESDAY
NIGHT INTO WEDNESDAY...THEN USHERED OUT BY UPPER LEVEL SHORT WAVE
THAT PUSHES THROUGH THE MISSISSIPPI AND TENNESSEE VALLEYS BY
WEDNESDAY NIGHT. HAVE KEPT SLIGHT CHANCE TO CHANCE POPS ACROSS THE
SOUTHEASTERN THIRD OF THE CWA THROUGH WEDNESDAY...WITH DIMINISHING
POPS OVERNIGHT WEDNESDAY NIGHT INTO THURSDAY. SURFACE HIGH
PRESSURE KEEPS DRY CONDITIONS IN PLACE THROUGH THE REMAINDER OF
THE WEEK AHEAD OF THE NEXT SYSTEM OVER THE WEEKEND. SEASONAL
TEMPERATURES EXPECTED THROUGH MID WEEK...THEN AS RIDGE SETTLES
OVER THE AREA...A SLIGHT WARM UP IS EXPECTED. EXTENDED MODELS
STILL HAVING DIFFICULTY RESOLVING THE WEEKEND SYSTEM...AND HAVE
OPTED TO GO WITH THE ECMWF SOLUTION AS IT APPEARS TO BETTER HANDLE
THE DEVELOPMENT AND PROGRESSION OF THINGS. EURO CURRENTLY
ADVERTISING UPPER LOW QUICKLY SPEEDING ACROSS THE SOUTHWEST U.S.
AND INTO THE CENTRAL PLAINS BY SATURDAY MORNING. SURFACE FEATURE
WILL MOVE INTO THE UPPER MIDWEST BY LATE SATURDAY...DRAGGING THE
ASSOCIATED COLD FRONT INTO NORTHWEST GEORGIA. GIVEN THERE IS STILL
SOME UNCERTAINTY WITH THIS SYSTEM...AND THAT MODEL SOLUTIONS
DIVERGE SIGNIFICANTLY...HAVE ONLY GONE WITH SLIGHT CHANCE OR
CHANCE POPS THROUGH THE WEEKEND. AS OF NOW...INSTABILITY STILL
APPEARS LIMITED ENOUGH TO KEEP MENTION OF THUNDER OUT.

31

&&

.AVIATION...
06Z UPDATE...
MAINLY VFR CONDITIONS ACROSS THE NORTHWESTERN HALF OF THE FORECAST
AREA AT THIS TIME WITH A WIDE MIXTURE OF VFR TO LIFR CONDITIONS
ACROSS THE SOUTHEASTERN HALF DUE MAINLY TO FOG. WIDESPREAD MVFR
CEILINGS ARE EXPECTED TO DEVELOP BY 10Z ACROSS THE AREA WITH LOCAL
IFR TO LIFR CONDITIONS...MAINLY ACROSS THE SOUTHEASTERN HALF OF THE
AREA...DUE TO FOG CONTINUING THROUGH 14Z. CONDITIONS IMPROVING FROM
MVFR TO MOSTLY VFR BY 18Z OUTSIDE OF AREAS PRECIPITATION. SHOWERS
WILL SPREAD INTO THE FORECAST AREA FROM THE NORTHWEST BEGINNING
AFTER 10Z. SCATTERED TO NUMEROUS SHOWERS AND A FEW THUNDERSTORMS
WILL MOVE ACROSS THE AREA BETWEEN 12Z AND 00Z. SOUTHEAST TO
SOUTHWEST WINDS 2-6KT ARE EXPECTED THROUGH 12Z...BECOMING
PREDOMINATELY SOUTHWEST AFTER 12Z. WIND SPEEDS WILL INCREASE INTO
THE 8-12KT RANGE BY 16Z WITH GUSTS 16-22KT. NORTHWEST WINDS WILL
SPREAD FROM NORTHWEST TO SOUTHEAST ACROSS THE AREA AFTER 00Z WITH
SPEEDS 7-10KT AND GUSTS 12-18KT.

//ATL CONFIDENCE...06Z UPDATE...
MEDIUM ON TIMING OF CONVECTION TODAY AND CEILINGS/VISIBILITIES EARLY
THIS MORNING. HIGH OTHER ELEMENTS.

20

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          67  44  56  41 /  70  60  10  20
ATLANTA         66  39  52  38 /  70  60  10  10
BLAIRSVILLE     61  36  48  32 /  90  60  10  10
CARTERSVILLE    64  37  49  32 /  90  50  10  10
COLUMBUS        71  44  54  41 /  70  60  10  20
GAINESVILLE     66  40  52  38 /  70  60  10  10
MACON           71  48  59  41 /  50  50  20  40
ROME            62  34  48  30 / 100  40  10  10
PEACHTREE CITY  66  39  52  34 /  70  60  10  10
VIDALIA         76  58  64  48 /  30  30  30  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 11 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR THE FOLLOWING ZONES: CATOOSA...CHATTOOGA...DADE...FANNIN...
GILMER...LUMPKIN...MURRAY...TOWNS...UNION...WALKER...WHITE...
WHITFIELD.

&&

SHORT TERM...20
LONG TERM....31
AVIATION...20

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
508 AM EST MON DEC 10 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-111015-
BALDWIN-BANKS-BARROW-BARTOW-BIBB-BLECKLEY-BUTTS-CARROLL-CATOOSA-
CHATTAHOOCHEE-CHATTOOGA-CHEROKEE-CLARKE-CLAYTON-COBB-COWETA-
CRAWFORD-CRISP-DADE-DAWSON-DEKALB-DODGE-DOOLY-DOUGLAS-EMANUEL-
FANNIN-FAYETTE-FLOYD-FORSYTH-GILMER-GLASCOCK-GORDON-GREENE-
GWINNETT-HALL-HANCOCK-HARALSON-HARRIS-HEARD-HENRY-HOUSTON-JACKSON-
JASPER-JEFFERSON-JOHNSON-JONES-LAMAR-LAURENS-LUMPKIN-MACON-
MADISON-MARION-MERIWETHER-MONROE-MONTGOMERY-MORGAN-MURRAY-
MUSCOGEE-NEWTON-NORTH FULTON-OCONEE-OGLETHORPE-PAULDING-PEACH-
PICKENS-PIKE-POLK-PULASKI-PUTNAM-ROCKDALE-SCHLEY-SOUTH FULTON-
SPALDING-STEWART-SUMTER-TALBOT-TALIAFERRO-TAYLOR-TELFAIR-TOOMBS-
TOWNS-TREUTLEN-TROUP-TWIGGS-UNION-UPSON-WALKER-WALTON-WARREN-
WASHINGTON-WEBSTER-WHEELER-WHITE-WHITFIELD-WILCOX-WILKES-
WILKINSON-
508 AM EST MON DEC 10 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...TODAY AND TONIGHT...

A STRONG COLD FRONT WILL MOVE INTO NORTH GEORGIA TODAY. THERE IS A
CHANCE OF STRONG TO ISOLATED SEVERE THUNDERSTORMS AHEAD OF THE
FRONT...GENERALLY OVER NORTHWEST AND WEST CENTRAL GEORGIA INTO THE
AFTERNOON. A SLIGHT CHANCE OF THUNDERSTORMS WILL CONTINUE INTO
CENTRAL GEORGIA THROUGH TONIGHT. THE PRIMARY HAZARDS IN ANY
THUNDERSTORM THAT DEVELOPS WILL BE GUSTY WINDS...LIGHTNING...AND
BRIEF HEAVY RAIN. IN SEVERE THUNDERSTORMS...DAMAGING WINDS WILL BE
THE PRIMARY CONCERN WITH A POSSIBLE ISOLATED TORNADO OR TWO. AS
THE FRONT PUSHES INTO CENTRAL GEORGIA...THE THREAT OF SEVERE
STORMS DIMINISHES DUE TO LIMITED INSTABILITY.

IN ADDITION TO THE THUNDERSTORM POTENTIAL...THE STRONG LOW-LEVEL
JET WILL PRODUCE 15 TO 25 MPH WINDS WITH GUSTS TO 40 MPH IN THE
NORTH GEORGIA MOUNTAINS...GENERALLY ABOVE 1500 FEET. WINDS ARE
EXPECTED TO DIMINISH THIS EVENING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

ANOTHER FRONT IS EXPECTED TO MOVE THROUGH THE STATE INTO THE
WEEKEND. INSTABILITY REMAINS LIMITED WITH THIS SYSTEM...AND ONLY
EXPECTING SHOWERS AT THIS TIME. THERE IS STILL SOME UNCERTAINTY
WITH THIS EVENT. STAY TUNED FOR FORECAST UPDATES ON THIS EVENT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME...HOWEVER SPOTTERS
ARE ENCOURAGED TO SUBMIT REPORTS OF SEVERE WEATHER THROUGH THE WEB
BY GOING TO WEATHER.GOV/ATLANTA.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
512 AM EST MON DEC 10 2012

GAZ001>003-011-101115-
512 AM EST MON DEC 10 2012

...SIGNIFICANT WEATHER ADVISORY FOR 40 MPH WINDS IN WALKER...
CATOOSA...CHATTOOGA AND DADE COUNTIES UNTIL 615 AM EST...

AT 506 AM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED A LINE
OF STRONG THUNDERSTORMS FROM NORTHWEST OF COLE CITY TO SOUTHWEST OF
CHATTOOGAVILLE...MOVING EAST AT 50 MPH.

WIND GUSTS OF 40 MPH ARE LIKELY AS THESE STORMS MOVE ACROSS WALKER...
CATOOSA...CHATTOOGA AND DADE COUNTIES THROUGH 615 AM EST. SOME
LOCATIONS IN THE PATH OF THESE STORMS INCLUDE COLE CITY...HOOKER...
MORGANVILLE...STEPHENSVILLE...NEW ENGLAND...TRENTON...LOOKOUT
MOUNTAIN...WILDWOOD...RISING FAWN...CLOUDLAND CANYON STATE PARK...
CHATTANOOGA VALLEY...CEDAR GROVE...CLOUDLAND...FORT OGLETHORPE AND
LAKEVIEW.

THESE WIND GUSTS MAY PRODUCE MINOR DAMAGE TO TREE LIMBS AND BLOW
LIGHT...UNSECURED OBJECTS AROUND.

&&

LAT...LON 3498 8502 3481 8514 3473 8517 3472 8505
      3459 8506 3458 8511 3443 8518 3436 8534
      3428 8539 3429 8547 3498 8561
TIME...MOT...LOC 1011Z 268DEG 43KT 3511 8578 3468 8607
          3403 8631