Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1230 PM EST TUE MAR 5 2013

.PREV DISCUSSION... /ISSUED 1058 AM EST TUE MAR 5 2013/

..WINTER WEATHER ADVISORY FOR NORTHEAST GEORGIA TONIGHT...
..WIND ADVISORY FOR ALL AREAS THROUGH WEDNESDAY...

UPDATE...MAIN FEATURE OF INTEREST ACROSS THE SOUTHEAST STATES
TODAY WILL BE STRONG SURFACE TROUGH CURRENTLY MOVING THROUGH THE
TENNESSEE AND LOWER MISSISSIPPI VALLEYS. INTERACTION BETWEEN THIS
TROUGH AND RIDGE OF HIGH PRESSURE OVER FLORIDA IS ALLOWING
GRADIENT TO TIGHTEN LOCALLY WITH GUSTS TO 30 MPH ALREADY OVER NW
PORTIONS. AS SHOWERS AND STORMS WHICH ARE OVER MISSISSIPPI AND
ALABAMA MOVE OVER THE LOCAL AREA...SHOULD SEE ADDITIONAL WINDS MIX
DOWN THIS AFTERNOON AND HAVE OPTED FOR WIND ADVISORY FOR ALL
ZONES. THESE WINDS MAY SEE A BRIEF LULL INTO THE OVERNIGHT HOURS
BUT SHOULD INCREASE RAPIDLY AGAIN WEDNESDAY MORNING. FRO
SIMPLICITY SAKE...JUST CARRIED ADVISORY THROUGH THE ENTIRE PERIOD.

AS FOR THE SEVERE POTENTIAL...A GOOD PORTION OF NORTH CENTRAL
GEORGIA NOW IN SLIGHT RISK FROM SPC. SHEAR PARAMETERS WILL
CERTAINLY BE SUFFICIENT FOR SEVERE STORMS WITH 50 KNOTS OF 0-1KM
SHEAR AND 0-1KM HELICITY IN EXCESS OF 300 M2/S2 AFTER 18Z.
QUESTION WILL BE INSTABILITY WHICH IS GIVING SOME CONCERN AS
MODELS HAVE INCREASED WITH THE LATEST RUN WITH 500 TO 1000 J/KG
OVER ALL BUT THE EXTREME NORTH. WHEN TAKEN WITH SHEAR
VALUES...NAM12 NOW SHOWING STP APPROACHING 4 THIS AFTERNOON. STILL
LOOKS LIKE A CONDITIONAL DAY...BUT GIVEN SURGE OF DEWPOINTS AND
CURRENT CLEARING ALLOWING FOR INSOLATION...AM LEANING TOWARD AT
LEAST ISOLATED SEVERE FOR THIS AFTERNOON.

AS SYSTEM CLEARS TONIGHT...WRAP AROUND SHOULD ALLOW FOR SNOW
SHOWERS TO DEVELOP AS IS CURRENTLY ADVERTISED. EXPECTING MAINLY A
HALF AND INCH TO AN INCH WITH ISOLATED HIGHER AMOUNTS. GIVEN
TIMING FOR THE MORNING COMMUTE AND POTENTIAL FOR ICY ROADS...HAVE
OPTED FOR A WINTER WEATHER ADVISORY.

DEESE

PREV DISCUSSION... /ISSUED 645 AM EST TUE MAR 5 2013/

SHORT TERM /TODAY THROUGH WEDNESDAY/...
STRONG CLOSED SURFACE LOW MOVING THROUGH THE OHIO/TENNESSEE VALLEYS
TODAY AND THEN PULLING NORTHEAST THIS EVENING. THIS LOW WILL PULL A
COLD FRONT ACROSS THE CWA THIS AFTERNOON AND EVENING. SHOWERS WILL
DEVELOP AHEAD OF THIS SYSTEM AND SPREAD ACROSS THE FORECAST AREA
TODAY. SCATTERED THUNDERSTORMS ARE EXPECTED. WITH THE COMBINATION OF
STRONG WIND SHEAR AND INSTABILITY A FEW THUNDERSTORMS COULD BE
SEVERE. FRONT MOVES RAPIDLY THROUGH THE CWA AND RAIN SHOULD BE
ENDING FROM THE WEST LATE AFTERNOON INTO EARLY EVENING. MEANWHILE
THE DEEPENING TROUGH ALOFT SHOULD BRING WRAP AROUND MOISTURE INTO
GEORGIA OVERNIGHT AND INTO WEDNESDAY MORNING. WITH LOW THICKNESS
VALUES IN PLACE...RAIN MIXING WITH AND CHANGING TO SNOW IS EXPECTED
ACROSS THE NORTH LATE TONIGHT INTO WEDNESDAY MORNING. ESTIMATES OF
UP TO A HALF INCH NORTHWEST AND UP TO AN INCH IN THE NORTHEAST STILL
LOOK OKAY. A WIND ADVISORY MAY BE NEEDED FOR TONIGHT AND WEDNESDAY
FOR GUSTY WEST TO NORTHWEST WINDS. HAVE STAYED CLOSE TO A MAV/MET
BLEND...BUT WITH COLD AIR ADVECTION ON WEDNESDAY HAVE FAVORED THE
COOLER HIGHS.

41

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
WRAP AROUND MOISTURE WITH THE SYSTEM IN THE SHORT TERM SHOULD HAVE
ALREADY EXITED THE AREA BY WEDNESDAY NIGHT BUT IT WILL BE ANOTHER
COLD NIGHT ACROSS THE CWA. WITH CURRENT FORECAST A FREEZE WARNING
MAY BE NEEDED FOR WEDNESDAY NIGHT ACROSS MUCH OF THE CWA. RIDGING
WILL BUILD INTO THE CWA ON THURSDAY AND DOMINATE THROUGH THE
WEEKEND. AS THE RIDGE STRENGTHENS ACROSS THE AREA...THE INITIAL
COOLER TEMPERATURES WILL WARM FOR THE WEEKEND...GIVING US A FEW DAYS
REPRIEVE FROM THE RECENT FRIGID TEMPERATURES. SHOULD WARM UP INTO
THE 60S SATURDAY AND SUNDAY WITH THE SOUTHERN PORTION OF CWA HAVING
THE POTENTIAL TO SEE THE LOW 70S ON SUNDAY. THIS WILL PUT US CLOSE
TO CLIMATOLOGY FOR HIGHS OVER THE WEEKEND.

NEXT RAIN EVENT ISNT UNTIL LATE IN THE LONG TERM OR JUST BEYOND THE
END OF IT. GFS AND ECMWF ARE IN POOR AGREEMENT WITH THE NEXT SYSTEM.
GFS BRINGS THE SFC LOW INTO THE TN VALLEY SUNDAY NIGHT AND BRINGS
THE RAIN CHANCES BACK TO THE CWA. IT THEN PUSHES THE FRONT THROUGH
ON MONDAY AND STALLS IT ACROSS SOUTHERN GA MONDAY NIGHT. 00Z ECMWF
IS A LITTLE MORE IN LINE THAN THE 12Z ECMWF...BUT STILL SLOWER THAN
THE GFS AS THE ECMWF DOESNT BRING RAIN INTO THE CWA UNTIL MONDAY
NIGHT. PATTERN IN GFS LOOKS MORE REALISTIC SO FORECAST TAKES THE
GFS SOLUTION...BUT CONFIDENCE WITH THE TIMING OF THIS NEXT SYSTEM
IS VERY LOW.

11

FIRE WEATHER...
FUELS ARE DRY ACROSS MUCH OF NORTH AND CENTRAL GEORGIA. WINDS WILL
BE GUSTY TODAY AND ARE EXPECTED TO REACH THE 15 MPH CRITERIA
ACROSS CENTRAL GEORGIA. WOULD NORMALLY ISSUE A FIRE DANGER
STATEMENT BUT BECAUSE RAIN IS EXPECTED TO MOVE IN BEFORE THE WINDS
START REACHING THIS CRITERIA...WILL NOT ISSUE A FIRE DANGER
STATEMENT.

AVIATION...
12Z UPDATE...
CEILINGS GRADUALLY LOWERING TO MVFR THIS MORNING. SOME LIGHT RAIN
SHOWING UP ON RADAR OVER THE TAF SITES BUT RAIN WILL BE INCREASING
LATER TODAY WITH IFR CEILINGS EXPECTED BY AFTERNOON. ISOLATED TO
SCATTERED THUNDER EXPECTED BUT WILL LEAVE OUT OF TAFS UNTIL LOCATION
OF STORMS BECOMES MORE EVIDENT. COLD FRONT CROSSING THE FORECAST
AREA 22Z TO 01Z WITH SOME IMPROVEMENT IN CEILINGS. WINDS SOUTHWEST
10 TO 15KT AND GUSTY TODAY BECOMING WEST TO NORTHWEST AND GUSTY
BEHIND THE FRONT.

//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON IFR CIGS AND TIMING OF RAIN. HIGH CONFIDENCE
ALL OTHER ELEMENTS.

41

&&

.AVIATION...
18Z UPDATE...
PRECIPITATION ARRIVAL HAS BEEN DELAYED WITH LATEST SHORT TERM
MODELS NOW SHOWING BEST TIMES BETWEEN 20Z AND 00Z WED.
THUNDERSTORMS HAVE DEVELOPED OVER PORTIONS OF ALABAMA AND EXPECT
THUNDERSTORM COVERAGE TO INCREASE SLIGHTLY AS IT ENTERS THE LOCAL
AIRSPACE. FOR THIS REASON...HAVE ADDED TEMPO FOR TSRA FOR
AFOREMENTIONED TIMEFRAME. PRECIP CLEARS BUT SHOULD SEE VFR WITH
POTENTIAL FOR MVFR CIGS TO STICK AROUND INTO THE OVERNIGHT HOURS.
WINDS WILL BE AN ISSUE THROUGH THE ENTIRE TAF PERIOD WITH GUSTS TO
35KTS LIKELY ON WEDNESDAY.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON TSRA POTENTIAL AND TIMING.
HIGH ON REMAINING ELEMENTS.

DEESE

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          65  34  51  30 /  80  70   5   5
ATLANTA         64  31  47  31 /  80  50  10   0
BLAIRSVILLE     56  31  40  29 /  90  70  60  10
CARTERSVILLE    65  32  47  30 /  80  50  20   5
COLUMBUS        70  35  53  32 /  60  40   5   0
GAINESVILLE     62  32  45  32 /  80  70  10   5
MACON           68  37  53  31 /  60  40   5   0
ROME            64  32  47  30 /  80  40  20   5
PEACHTREE CITY  66  33  50  28 /  70  40   5   0
VIDALIA         71  41  57  37 /  30  30   0   0

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 PM EST WEDNESDAY FOR THE FOLLOWING ZONES:
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.

WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
WEDNESDAY FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...
LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WHITE.

&&

SHORT TERM...DEESE
LONG TERM....20
AVIATION...DEESE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1037 AM EST TUE MAR 5 2013

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-061545-
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-
1037 AM EST TUE MAR 5 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

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

...ISOLATED SEVERE STORMS POSSIBLE ACROSS MUCH OF NORTH AND
CENTRAL GEORGIA THIS AFTERNOON AND THIS EVENING...
...CHANCE OF ACCUMULATING SNOW ACROSS FAR NORTH GEORGIA TONIGHT
INTO WEDNESDAY...

WEATHER HAZARDS EXPECTED...
ISOLATED SEVERE STORMS WILL BE POSSIBLE ACROSS MUCH OF CENTRAL
AND NORTH GEORGIA...WITH THE MAIN THREATS BEING DAMAGING WIND AND
HAIL. ISOLATED TORNADOES ARE POSSIBLE.

LATER TONIGHT...ISOLATED TO SCATTERED SNOW SHOWERS ARE POSSIBLE
ACROSS FAR NORTH GEORGIA...LASTING INTO WEDNESDAY MORNING. IN
GENERAL...A HALF OF AN INCH TO AN INCH OF SNOWFALL ACCUMULATION IS
POSSIBLE NORTH OF A LINE FROM CHATSWORTH TO JASPER...DAWSONVILLE...
DAHLONEGA AND CLEVELAND...WITH UP TO 2 INCHES AT THE HIGHEST
ELEVATIONS OF THE NORTHEAST GEORGIA MOUNTAINS. A HALF INCH OR LESS OF
SNOW IS POSSIBLE NORTH OF A LINE FROM ROME TO GAINESVILLE.

DISCUSSION...
A COLD FRONT WILL MOVE THROUGH NORTH AND CENTRAL GEORGIA TODAY
BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. INSTABILITY WITH THIS
SYSTEM IS SOMEWHAT LIMITED...BUT WILL BE SUFFICIENT FOR ISOLATED TO
SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS NORTH AND
CENTRAL GEORGIA. WITH A GOOD AMOUNT OF DEEP LAYER SHEAR AND MODERATE
LOW LEVEL SHEAR...ISOLATED SEVERE STORMS WILL BE POSSIBLE. THE MAIN
THREATS WILL BE DAMAGING WIND AND HAIL...BUT THERE IS ENOUGH LOW
LEVEL SHEAR FOR POSSIBLE ISOLATED TORNADOES. THE BEST TIMING FOR
THESE THUNDERSTORMS WILL BE AFTER NOON INTO THE EARLY EVENING.

AS THE COLD FRONT EXITS THE REGION TONIGHT...MOISTURE ASSOCIATED
WITH THIS SYSTEM WILL COMBINE WITH COLD TEMPERATURES...BRINGING THE
CHANCE OF SNOW SHOWERS TO FAR NORTH GEORGIA....GENERALLY NORTH OF A
LINE FROM ROME TO GAINESVILLE. BY MIDNIGHT...RAIN IS EXPECTED TO
TRANSITION TO A RAIN/SNOW MIX AND THEN TO MOSTLY SNOW BEFORE
SUNRISE. ISOLATED TO SCATTERED FLURRIES OR SNOW SHOWERS WILL CONTINUE
INTO WEDNESDAY MORNING BEFORE DIMINISHING BY WEDNESDAY AFTERNOON.
WITH FREEZING TEMPERATURES EXPECTED ACROSS THE FAR NORTH LATE TONIGHT
AND EARLY WEDNESDAY...ALONG WITH WET ROADWAYS...SOME ROADS MAY BECOME
SLICK AND DANGEROUS LATE TONIGHT INTO WEDNESDAY MORNING. PLEASE SEE
OUR WINTER WEATHER ADVISORY /WSWFFC/ FOR MORE DETAILS.

FINALLY...A TIGHT SURFACE PRESSURE GRADIENT DEVELOPING ACROSS THE
REGION TODAY WILL BRING WINDS OF 15 TO 25 MPH WITH GUSTS AS HIGH AS
35 TO 40 MPH THIS AFTERNOON AND TONIGHT. WINDS THIS STRONG COULD
TOPPLE WEAK OR DROUGHT STRESSED TREES. PLEASE SEE OUR WIND ADVISORY
/NPWFFC/ FOR MORE DETAILS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY...

DISCUSSION...
THE WRAP AROUND MOISTURE FROM AN EXITING LOW PRESSURE SYSTEM WILL
CONTINUE THE CHANCE FOR ISOLATED TO SCATTERED FLURRIES OR SNOW
SHOWERS ACROSS FAR NORTH GEORGIA THROUGH MID DAY ON WEDNESDAY. IN
ADDITION...WITH THE TIGHT SURFACE PRESSURE GRADIENT BEHIND THIS
SYSTEM...WINDS ARE FORECAST TO BE 20 TO 25 MPH WITH GUSTS AS HIGH AS
35 TO 40 MPH. WINDS THIS STRONG COULD TOPPLE WEAK OR DROUGHT STRESSED
TREES. FREEZING TEMPERATURES ARE EXPECTED WEDNESDAY NIGHT AND A
FREEZE WARNING WILL LIKELY BE NEEDED.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT REQUESTED BUT 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
213 PM EST TUE MAR 5 2013

GAZ001-002-051945-
213 PM EST TUE MAR 5 2013

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN NORTHERN WALKER AND NORTHERN DADE COUNTIES UNTIL 245 PM EST...

AT 205 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM ABOUT 10 MILES WEST OF TRENTON...MOVING
NORTHEAST AT 70 MPH. HAIL TO THE SIZE OF DIMES AND WIND GUSTS TO 40
MPH ARE POSSIBLE WITH THIS STORM AS IT AFFECTS NEW ENGLAND...
WILDWOOD...NORTHERN PARTS OF LOOKOUT MOUNTAIN AND ROSSVILLE.

SIGNIFICANT WEATHER ADVISORIES ARE ISSUED FOR WINDS UP TO 50 MPH...
HAIL LESS THAN THE SIZE OF QUARTERS...OR SIGNIFICANT CLOUD-TO-GROUND
LIGHTNING.

&&

LAT...LON 3499 8526 3497 8527 3487 8559 3488 8559
      3495 8561 3498 8561 3499 8560
TIME...MOT...LOC 1912Z 245DEG 61KT 3494 8553