Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
159 PM EDT MON SEP 3 2012

.PREV DISCUSSION... /ISSUED 729 AM EDT MON SEP 3 2012/

SHORT TERM /TODAY THROUGH TUESDAY/...
/ISSUED 407 AM EDT MON SEP 3 2012/
REMNANTS OF ISAAC HAVE MOVED INTO THE TN AND OH VALLEYS...AND
CONTINUE TO BE A FORECAST HEADACHE FOR THE SOUTHEAST THROUGH THE
SHORT TERM. THOUGH WEAKENING OF THE UPPER LOW IS EXPECTED INTO
TUESDAY AS THE SYSTEM IS ABSORBED IN ZONAL FLOW ALOFT...ONLY LITTLE
MOVEMENT IS EXPECTED. AS A RESULT HAVE LIKELY POPS ACROSS MUCH OF
NORTH GEORGIA TODAY...SPREADING INTO CENTRAL GEORGIA TONIGHT AND
TUESDAY.

EARLY MORNING BAND OF PRECIP MOVING INTO NW GA HAS LOST MUCH OF ITS
PUNCH...AND JUST GENERALLY SEEING SHOWERS AT THIS TIME. WITH THE
INFLUENCE OF DAYTIME HEATING...EXPECTING SCATTERED THUNDERSTORMS TO
DEVELOP. INSTABILITIES WILL INCREASE INTO THE 1500-2500 J/KG RANGE
AND WILL SUPPORT SOME STRONG STORMS. A FEW MAY BE SEVERE. MOIST
VERTICAL COLUMN AND HIGH FREEZING LEVEL WILL KEEP HAIL EVENTS TO A
MINIMUM. ALTHOUGH GFS/NAM INDICATING ONLY 20-25KTS OF 0-1KM SHEAR
TODAY...LOCAL WRF HIGHLIGHTING AREAS OF HIGH 0-1KM HELICITY BY MID
MORNING. AS A RESULT...AN ISOLATED TORNADO OR TWO CAN NOT BE RULED
OUT THROUGH TODAY. DAMAGING WIND WILL ALSO BE A THREAT IN ORGANIZED
CONVECTION...INCLUDING POSSIBLE DOWNBURSTS...DUE TO THE STEEP LAPSE
RATES AND MOIST BOUNDARY LAYER.

AS TROUGH CONTINUES TO SINK SOUTHWARD INTO TONIGHT...MODELS
INDICATING POSSIBLE MCS DEVELOPMENT OVERNIGHT JUST WEST OF THE CWA.
HAVE KEPT POPS HIGH INTO TUESDAY MORNING...WITH GENERALLY LIKELY
ACROSS MUCH OF THE CWA. ALTHOUGH BEST DESTABILIZATION WILL OCCUR
THIS AFTERNOON AND EVENING...THERE SHOULD BE ENOUGH INSTABILITY TO
SUPPORT ISOLATED TO SCATTERED THUNDERSTORMS THROUGH THE OVERNIGHT
HOURS.

PRECIPITATION AMOUNTS OF 1-2 INCHES CAN BE EXPECTED ACROSS MUCH OF
THE AREA THROUGH THE SHORT TERM...AND WITH FLASH FLOOD GUIDANCE WELL
ABOVE THIS...DO NOT ANTICIPATE ANY ISSUES. THAT BEING SAID...UPSLOPE
FLOW AND TRAINING OF CELLS COULD ENHANCE PRECIP AMOUNTS IN NE
GA...AND WILL HAVE TO KEEP AN EYE ON ACTIVITY IN THAT AREA.

AS FOR TEMPERATURES...HAVE GONE WITH A BLEND OF THE MODELS...AND
WHERE NECESSARY...HAVE GONE WITH THE MAV WHICH HAS BEEN MORE
SKILLFUL OVER THE LAST FEW DAYS. AMPLE CLOUD COVER AND PRECIP
ACTIVITY WILL KEEP SLIGHTLY COOLER HIGH TEMPERATURES IN PLACE TODAY
AND TUESDAY.

31

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
/ISSUED 407 AM EDT MON SEP 3 2012
TROPICAL MOISTURE BECOMES STRETCHED OUT ACROSS THE CWA THROUGH
WEDNESDAY WITH SOME HINT AT DRYING THURSDAY INTO FRIDAY AS THE
UPPER RIDGE NOSES EASTWARD. HAVE NOT REMOVED POPS FOR THE BRIEF
DRIER PERIOD...JUST REDUCED THEM OVER MUCH OF THE CWA. BY THE
WEEKEND BOTH MODELS SHOW A SIGNIFICANT CLOSED LOW DEVELOPING
VICINITY OF THE OHIO VALLEY. THIS KEEPS THE UNSETTLED WEATHER OVER
THE CWA AND HAVE CONTINUED WITH CHANCE OR SLIGHT CHANCE POPS.
MODEL MAX TEMPERATURES LOOKED A BIT HIGH GIVEN THE UPPER PATTERN
SO HAVE TWEAKED THEM DOWN A BIT MOST AREAS.

41

&&

.AVIATION...
18Z UPDATE...
CURRENT RADAR LOOP SHOWS SHOWERS AND ISOLATED THUNDERSTORMS MOVING
INTO THE AREA. SHRA/TSRA ACTIVITY HAVING A HARD TIME GETTING INTO
THE AIRPORTS AIRSPACE SO HAVE BACKED UP THE TIMING ON PRECIP IN
THE TAF. PRECIP SHOULD START AFFECTING ATL BY 20Z-21Z.
PRECIPITATION IS EXPECTED TO CONTINUE OFF AND ON THROUGH THE TAF
PERIOD. WINDS WILL STY OUT OF THE W-SW WITH SPEEDS IN THE 5-10KT
RANGE. CEILINGS HOOVERING AROUND 2500-3500FT AT THE MOMENT. THEY
ARE EXPECTED TO LIFT A BIT THROUGH 00Z THEN FALL BACK INTO THE
MVFR TO IFR RANGE THROUGH TUESDAY MORNING.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS...EXCEPT HIGH ON WINDS.

01

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          87  71  86  70 /  70  60  70  40
ATLANTA         86  72  85  73 /  70  70  70  40
BLAIRSVILLE     80  68  80  65 /  80  70  70  50
CARTERSVILLE    86  71  85  71 /  80  70  70  50
COLUMBUS        91  74  88  73 /  60  70  70  50
GAINESVILLE     83  71  84  70 /  70  70  70  50
MACON           90  72  88  72 /  60  70  60  50
ROME            87  72  86  70 /  80  70  70  40
PEACHTREE CITY  87  71  85  70 /  70  70  70  40
VIDALIA         92  73  90  73 /  40  40  40  30

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...01
LONG TERM....DEESE
AVIATION...01

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
154 PM EDT MON SEP 3 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-041800-
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-
154 PM EDT MON SEP 3 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT...
ISOLATED SEVERE STORMS LIKELY THIS EVENING.

.SYNOPSIS...
TROPICAL MOISTURE WILL PERSIST OVER NORTH AND CENTRAL GEORGIA
THROUGH TONIGHT. THE REMNANTS OF TROPICAL STORM ISAAC HAVE MOVED
INTO THE OHIO AND TENNESSEE VALLEYS.

.PRIMARY HAZARDS...
THE PRIMARY HAZARDS FROM THUNDERSTORMS WILL BE DAMAGING
WINDS...PERIODS OF HEAVY RAIN WITH POSSIBLE STREET FLOODING AND
OCCASIONAL LIGHTNING. THERE WILL BE AN ISOLATED TORNADO RISK THIS
EVENING OVER SOUTH AND SOUTHWEST PORTIONS OF THE AREA.

.DISCUSSION...
DEEP TROPICAL MOISTURE REMAINS OVER GEORGIA. THE DYNAMICS ASSOCIATED
WITH THE REMNANTS OF ISAAC WILL AFFECT THE TENNESSEE VALLEY TODAY
AND TONIGHT. MODERATE INSTABILITY...MODERATE VERTICAL SHEAR
COMBINED WITH THE ABUNDANT MOISTURE AND DAYTIME HEATING SHOULD
PRODUCE SCATTERED THUNDERSTORMS THROUGH TONIGHT. ISOLATED STORMS
WILL LIKELY BECOME SEVERE OVER PORTIONS OF SOUTH AND SOUTHWEST GEORGIA
THIS EVENING. ADDITIONAL SEVERE STORMS WILL BE POSSIBLE OVER
WESTERN SECTIONS THROUGH THE OVERNIGHT PERIOD.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...
THE TROPICAL AIR MASS WILL CONTINUE THROUGH MOST OF THE PERIOD WITH
SCATTERED THUNDERSTORMS POSSIBLE EACH DAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS 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
255 PM EDT MON SEP 3 2012

GAZ093>095-104>106-031945-
255 PM EDT MON SEP 3 2012

...SIGNIFICANT WEATHER ADVISORY FOR FREQUENT LIGHTNING IN SUMTER...
PEACH...MACON...CRISP...DOOLY AND HOUSTON COUNTIES UNTIL 345 PM
EDT...

AT 251 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM MARSHALLVILLE TO SUMTER...MOVING EAST AT 15
MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE FREQUENT CLOUD TO GROUND
LIGHTNING AND WIND GUSTS TO 35 MPH AS THEY MOVE ACROSS
SUMTER...PEACH...MACON...CRISP...DOOLY AND HOUSTON COUNTIES THROUGH
345 PM EDT. SOME LOCATIONS IN THE PATH OF THESE STORMS INCLUDE FLINT
RIVER WMA...DOOLING...BYROMVILLE...SUMTER...HUNTINGTON...METHVINS...
WINCHESTER...FIVE POINTS...MARSHALLVILLE...LAMAR...DRAYTON...
LILLY...SAINT LOUIS...LESLIE AND DESOTO. HEAVY DOWNPOURS WILL CAUSE
PONDING OF WATER ON ROADWAYS.

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 3189 8437 3219 8401 3248 8400 3255 8370
      3218 8363 3190 8398 3191 8432 3191 8433
      3188 8433 3187 8435
TIME...MOT...LOC 1853Z 271DEG 14KT 3246 8396 3219 8390
          3192 8423