Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1009 AM EDT TUE JUL 10 2012

.UPDATE...
ONLY MINOR TWEAKS PLANNED TO THE FORECAST THIS MORNING BASED ON
CURRENT TRENDS. NO CHANGES TO THE POPS THOUGH. DIURNALLY DRIVEN
THUNDERSTORMS EXPECTED AGAIN THIS AFTERNOON AND INTO TONIGHT. WITH
STATIONARY BOUNDARY JUST NORTH OF THE STATE MAY SEE STORMS LINGER
OVERNIGHT...PARTICULARLY ACROSS NORTH GEORGIA. ISOLATED SEVERE
STORMS WILL AGAIN BE POSSIBLE THIS AFTERNOON ACROSS THE CWA.

11

&&

.PREV DISCUSSION...

SHORT TERM /TODAY THROUGH WEDNESDAY/...
/ISSUED 505 AM EDT TUE JUL 10 2012/
MAIN FORECAST CONCERN CONTINUES TO BE PRECIP CHANCES AND QPF IN
ASSOCIATION WITH NEARLY STATIONARY FRONT NEAR NORTH GA AND PLENTIFUL
AVAILABLE MOISTURE. LATEST MODEL SOLUTIONS STILL HAVE SLIGHT
DIFFERENCES IN LOCATION OF THE FRONT... WITH THE NAM AND SREF
SLIGHTLY FARTHER SOUTHWARD THAN THE GFS. NONETHELESS THERE WILL BE
AMPLE MOISTURE AVAILABLE AND ENOUGH RADIATIONAL HEATING TO TRIGGER
CONVECTION ACROSS MUCH OF THE AREA. THE BEST CHANCE WILL BE NEAR
ATLANTA NORTHWARD... WITH LIKELY POPS THIS AFTERNOON INTO EVENING
AND AGAIN ON WEDNESDAY. CHANCE POPS WILL EXTEND SOUTHWARD. PROGGED
PW VALUES ARE AGAIN NEAR 1.80 INCHES FOR BOTH DAYS ALONG WITH WEAK
VERTICAL WIND SHEAR...THEREFORE IN COMBINATION WITH AMPLE CAPE...ANY
STORMS WILL CONTINUE TO HAVE THE MAIN THREATS OF SMALL HAIL...HEAVY
RAINFALL...AND GUSTY WINDS.

BOTH THE NAM AND GFS HAVE 24HR QPF VALUES UP NEAR AN INCH IN THE
NORTHEAST PART OF THE FORECAST HOUR ENDING AT 12Z WEDNESDAY. THEY
DIFFER GREATLY IN AMOUNTS SOUTHWARD WITH THE GFS NEAR 0.75-1.00
INCHES IN THE WEST AND 0.25 INCHES ELSEWHERE... WHILE THE NAM IS
ALMOST OPPOSITE HAVING THE EAST CENTRAL AREAS GETTING UP NEAR 0.75
INCHES AND THE WEST AND SOUTH 0.25 INCHES OR LESS. HPC GUIDANCE
APPEARS TO BE CLOSE TO A BLEND OF THESE SOLUTIONS...GENERALLY HAVING
0.50-0.75 INCHES NORTH OF ATLANTA AND LESS SOUTHWARD. THIS SEEMS
REASONABLE WHILE SOME LOCATIONS WILL OBVIOUSLY RECEIVE HIGHER
AMOUNTS FROM HEAVY DOWNPOURS IN THUNDERSTORMS. WEDNESDAY QPF ALSO
HAS DECENT DISCREPANCIES BETWEEN THE MODELS AS THE GFS HAS 12HR
TOTALS OF NEAR 0.75 INCHES FOR MUCH OF THE AREA EXCEPT THE FAR
SOUTH... WHILE THE NAM FOCUSES 0.50-1.00 INCHES NORTH OF ATLANTA.
ALL CONSIDERED...FROM TODAY THROUGH 00Z THURSDAY MANY LOCATIONS WILL
LIKELY RECEIVE 0.50-1.50 INCHES WITH THE HIGHEST AMOUNTS GENERALLY
BEING IN THE NORTHERN TO CENTRAL AREAS.

FOR TEMPS...USED BLEND OF MAV AND MET GUIDANCE WITH MINOR TWEAKS AND
RAISED MIN TEMPS FOR TUESDAY NIGHT IN SOME AREAS BASED ON PROGGED
CLOUD COVER AND PRECIP EFFECTS. HIGHS TODAY WILL GENERALLY BE IN THE
UPPER 80S TO LOW 90S IN MOST OF THE NORTH AND WEST... WITH MID 90S
SOUTHEAST... AND HIGHS WEDNESDAY WILL LIKELY BE 2-3 DEGREES COOLER
WITH MORE WIDESPREAD CLOUD COVER.

BAKER

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
/ISSUED 505 AM EDT TUE JUL 10 2012/
NO BIG CHANGES TO LONG TERM PATTERN. SURFACE BOUNDARY REMAINS
STALLED ACROSS GEORGIA FOR MUCH OF THE PERIOD WHILE A TROUGH
CONTINUES FROM THE LOWER MISSISSIPPI VALLEY INTO THE GULF.
ABUNDANT MOISTURE AND LIFT SHOULD AID CONVECTION THROUGH THE WEEK
MAINLY FAVORING THE NORTHERN SECTIONS. BY THE WEEKEND THE UPPER
RIDGE BEGINS TO BUILD WESTWARD INTO GEORGIA AND THE CAROLINAS WITH
THE ECMWF SHOWING A STRONGER RIDGE HOLDING THROUGH MONDAY. SO HAVE
LOWERED POPS A BIT FOR SATURDAY THROUGH MONDAY.

41

AVIATION...
12Z UPDATE...
/ISSUED 745 AM EDT TUE JUL 10 2012/
VFR CONDITIONS EXPECTED WITH EXCEPTION OF BRIEF MVFR FOG AT KAHN
THIS MORNING. WINDS SHOULD STAY MOSTLY W TO WSW AT 10KTS OR LESS
WITH SCT TO BKN CIGS AROUND 4-5 KFT STARTING AFTER ABOUT 15Z.
THERE IS A GOOD CHANCE FOR TSRA ESPECIALLY ACROSS THE NORTHERN
SITES AFTER 18Z AND INTO THE EVENING...HOWEVER FUTURE UPDATES MAY
TWEAK THE TIMING AS SEEN BEST FIT.

//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON TIMING OF TSRA LATER TODAY.
HIGH CONFIDENCE ALL ELSE.

BAKER

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          94  71  88  71 /  60  60  60  50
ATLANTA         91  72  87  71 /  60  50  60  60
BLAIRSVILLE     84  69  80  68 /  70  60  70  70
CARTERSVILLE    92  70  87  69 /  70  60  70  70
COLUMBUS        93  73  92  72 /  40  30  40  40
GAINESVILLE     91  71  85  71 /  70  60  70  70
MACON           94  72  93  73 /  40  30  40  50
ROME            92  70  89  72 /  70  60  70  70
PEACHTREE CITY  91  70  88  69 /  50  40  50  50
VIDALIA         96  76  94  75 /  30  30  40  40

&&

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

UPDATE...11
SHORT TERM...BAKER
LONG TERM....41
AVIATION...BAKER

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1032 AM EDT TUE JUL 10 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-111445-
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-
1032 AM EDT TUE JUL 10 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT...
ISOLATED SEVERE THUNDERSTORMS POSSIBLE THIS AFTERNOON AND TONIGHT
ACROSS NORTH AND CENTRAL GEORGIA.

.SYNOPSIS...
A FRONTAL BOUNDARY WILL LINGER ACROSS NORTH GEORGIA THROUGH
TONIGHT WHILE AN UPPER LEVEL LOW REMAINS OVER THE LOWER
MISSISSIPPI RIVER VALLEY.

.PRIMARY HAZARDS...
THE PRIMARY HAZARDS FROM THE THUNDERSTORMS WILL BE QUARTER SIZED HAIL...
60 MPH WIND GUSTS AND FREQUENT LIGHTNING. HEAVY RAIN IS ALSO
POSSIBLE. THE BEST TIME FOR THUNDERSTORM DEVELOPMENT WILL BE THIS
AFTERNOON THROUGH TONIGHT.

.DISCUSSION...
THE FRONTAL BOUNDARY AND THE UPPER LOW WILL COMBINE TO PRODUCE
MODERATE INSTABILITY AND ABUNDANT MOISTURE FOR SCATTERED ACROSS
CENTRAL GEORGIA...AND NUMEROUS THUNDERSTORMS ACROSS NORTH GEORGIA. WITH
CAPES INCREASING TO 2500 TO 3000...ISOLATED SEVERE STORMS ARE
POSSIBLE JUST ABOUT ANYWHERE IN NORTH AND CENTRAL GEORGIA. THE
MAIN THREAT WILL BE DAMAGING WINDS. PEA TO QUARTER SIZED HAIL IS
ALSO POSSIBLE...BUT MAINLY ACROSS NORTH GEORGIA.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY...
THERE IS A CHANCE FOR THUNDERSTORMS EACH DAY. DUE TO A PERSISTENT
SURFACE BOUNDARY...THUNDERSTORMS WILL BE MORE NUMEROUS ACROSS
NORTH GEORGIA THROUGH THE PERIOD...AND THERE REMAINS THE THREAT OF
ISOLATED SEVERE STORMS ACROSS THE ENTIRE REGION.

.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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
932 AM EDT TUE JUL 10 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0630 PM     TSTM WND DMG     BOSTWICK                33.74N 83.51W
07/09/2012                   MORGAN             GA   EMERGENCY MNGR

            17 TREES DOWN IN THE NORTHERN PART OF MORGAN COUNTY

1100 PM     TSTM WND DMG     ATLANTA                 33.75N 84.39W
07/09/2012                   FULTON             GA   EMERGENCY MNGR

            6 TO 8 TREES DOWN

&&

17

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1206 PM EDT TUE JUL 10 2012

GAZ002-011-019-101630-
1206 PM EDT TUE JUL 10 2012

...SIGNIFICANT WEATHER ADVISORY FOR PEA SIZED HAIL AND 40 MPH WINDS
IN WALKER...CHATTOOGA AND FLOYD COUNTIES UNTIL 1230 PM EDT...

AT 1203 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM 7 MILES NORTH OF VILLANOW TO 9 MILES WEST
OF CHATTOOGAVILLE...MOVING EAST AT 10 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE PEA SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS THEY MOVE
ACROSS WALKER...CHATTOOGA AND FLOYD COUNTIES THROUGH 1230 PM EDT.
SOME LOCATIONS IN THE PATH OF THESE STORMS INCLUDE BERRYTON...
SUMMERVILLE...MENLO...TRION...CLOUDLAND...SUTTLES MILL...NAOMI...
CENTER POST...LAFAYETTE...LINWOOD...ROCK SPRING...CHICKAMAUGA...
NOBLE...VILLANOW AND LYERLY. HEAVY DOWNPOURS WILL CAUSE PONDING OF
WATER ON ROADWAYS.

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

&&

LAT...LON 3486 8526 3485 8520 3478 8520 3477 8514
      3472 8517 3472 8505 3455 8506 3454 8509
      3447 8509 3418 8540 3419 8545 3463 8553
      3473 8546 3484 8545 3497 8537 3498 8527
TIME...MOT...LOC 1606Z 267DEG 9KT 3477 8507 3455 8521
          3430 8559