Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
219 PM EDT TUE APR 17 2012

.UPDATE...
/ISSUED 1142 AM EDT TUE APR 17 2012/
PRECIP SLOW TO MOVE INTO THE AREA...WITH MAIN ACTIVITY STILL BACK
OVER WESTERN ALABAMA. FRONT STILL EXPECTED TO STALL ACROSS THE CWA
THIS AFTERNOON...PROVIDING THE FOCUS FOR SHOWER AND THUNDERSTORM
DEVELOPMENT ACROSS THE AREA. HAVE MADE NO MAJOR CHANGES TO POPS
FOR TODAY...WITH PRE-FRONTAL DEVELOPMENT STILL EXPECTED WITH THE
HEATING OF THE DAY. HAVE MADE A FEW ADJUSTMENTS TO AFTERNOON
TEMPERATURES AND DEW POINTS GIVEN THE LATEST CONDITIONS. WITH
MODELED INSTABILITIES QUICKLY DIMINISHING AFTER 00Z...HAVE OPTED
TO EXCLUDE THUNDER FROM THE WX GRIDS OVERNIGHT.

ANY OTHER MAJOR CHANGES TO THE FORECAST WILL BE DONE WITH THE
AFTERNOON PACKAGE. NO ADDITIONAL UPDATES ARE ANTICIPATED AT THIS TIME.

31
&&

.SHORT TERM /TODAY THROUGH WEDNESDAY NIGHT/...
/ISSUED 416 AM EDT TUE APR 17 2012/
CURRENT SATELLITE LOOP SHOWS A COUPLE OF SHORT WAVES OVER THE
WESTERN GULF OF MEXICO THIS MORNING. THESE WAVES ARE ALONG THE
SOUTHERN TIP OF THE MAIN FRONTAL SYSTEM THAT IS MOVING INTO NW GA AT
THE MOMENT. THE MODELS ARE SHOWING THIS FRONT STALLING SOMEWHERE
ACROSS N GA TODAY ALLOWING THESE WAVES TO MOVE NORTHEASTWARD ALONG IT
AND INTO NORTH AND CENTRAL GA OVER THE NEXT 25 TO 48 HOURS. THE
MODELS ARE IN IN FAIRLY GOOD AGREEMENT IN THE SHORT TERM SHOWING THE
FRONT PUSHING INTO NORTH GEORGIA THIS MORNING BRINGING SHOWERS AND
ISOLATED THUNDER INTO THE STATE THROUGH WEDNESDAY. THE MAIN
AREA OF CONVECTION WITH THE FRONT IS CURRENTLY OUT OVER THE GULF AND
IT APPEARS TO BE BUILDING SOUTHEAST OVER THE GULF. IF THIS HOLDS
TRUE THEN THE BETTER CONVECTION MAY GET CUT OFF FROM THE MAIN LAND
AND STAY OVER THE GULF AS THIS FRONT MOVES EAST ACROSS THE REGION.
IT IS STILL HARD TO IGNORE THAT WITH THE PROXIMITY OF THE SURFACE
FRONT...DAY TIME HEATING...LIFTED INDEX VALUES OF -2 TO -4...AND
MLCAPES EXPECTED IN THE 500-1000J/KG RANGE TODAY. THIS IS WHY SPC
HAS NORTH AND PORTIONS OF CENTRAL GA IN A SLIGHT RISK AREA. WILL
CONTINUE WITH THE CURRENT THINKING OF THUNDERSTORMS TODAY AND
WEDNESDAY WITH THE BIGGEST CONCERN BEING DAMAGING WINDS.

01

.LONG TERM /THURSDAY THROUGH MONDAY/...
/ISSUED 416 AM EDT TUE APR 17 2012/
THE FRONT FINALLY MOVES THROUGH THE CWA...BUT STALLS JUST SOUTH
AND EAST OF THE STATE THURSDAY. AT THE SAME TIME...MODELS SHOW A
WEAK WAVE MOVING THROUGH THE FLOW THURSDAY MORNING THAT WILL
MAINTAIN LINGERING MOISTURE OVER AREA INTO THE AFTERNOON. AIR MASS
NEVER REALLY DRIES BEFORE THE APPROACHING STORM SYSTEM MOVING
THROUGH THE PLAINS STARTS TO IMPACT THE AREA. BY SATURDAY...GFS
HAS LOW OVER EAST TEXAS AND STRONGER THAN THE ECMWF...WHICH HAS AN
OPEN WAVE WITH TROUGH OVER MISSISSIPPI. SATURDAY NIGHT BOTH MODELS
HAVE LOW CLOSING OFF..BUT GFS STILL SLOWER OF THE TWO AND HOLDS
PRECIP OVER CWA THROUGH MONDAY...BUT DOES START TO DRY OUT FROM
NORTHWEST TO THE SOUTHEAST THROUGH THE AFTERNOON.

37

&&

.AVIATION...
18Z UPDATE...
DIFFICULT AVIATION FORECAST...PRECIP HAS BEEN SLOW
TO MOVE INTO THE AREA TODAY. BEST CHANCES FOR THUNDER THIS
AFTERNOON...GENERALLY 20-00Z. EXPECT DEGRADING CONDS THRU
WEDNESDAY MORNING WITH WIDESPREAD MVFR CIGS AND ISOL IFR CIGS.
VSBY RESTRICTIONS GENERALLY 3-5SM. EXPECT RAIN SHOWERS 06-15Z
TAPERING OFF INTO LATE MORNING/EARLY AFTERNOON WEDNESDAY AS MAIN
PRECIP AREA MOVES EAST. WINDS WILL BE LIGHT AND VARIABLE THIS
EVENING AND OVERNIGHT EXCEPT NEAR CONVECTION. EXPECTING SE WINDS
WEDNESDAY MORNING IN THE 4-6KT RANGE.

//ATL CONFIDENCE...18Z UPDATE...
MED CONFIDENCE ON ALL ELEMENTS EXCEPT LOW-MED CONFIDENCE ON WIND
DIRECTION AND TIMING OF TS/SHRA.

08

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          81  57  69  53 /  70  70  70  20
ATLANTA         78  58  69  56 /  70  70  60  20
BLAIRSVILLE     73  56  64  48 /  90  90  70  10
CARTERSVILLE    75  54  68  50 /  90  90  60  10
COLUMBUS        83  61  76  59 /  40  60  60  10
GAINESVILLE     76  56  65  53 /  90  90  70  20
MACON           86  59  75  57 /  40  50  60  20
ROME            73  55  72  51 /  90  90  60  10
PEACHTREE CITY  79  55  71  52 /  70  70  60  20
VIDALIA         83  63  77  58 /  20  30  60  40

&&

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

31/08/37/01

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1245 PM EDT TUE APR 17 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-181000-
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-
1245 PM EDT TUE APR 17 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT...
SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING
ACROSS NORTH AND CENTRAL GEORGIA. ISOLATED SEVERE THUNDERSTORMS ARE
EXPECTED THIS AFTERNOON AND EVENING.

.SYNOPSIS...
A COLD FRONT WAS APPROACHING NORTHWEST GEORGIA THIS AFTERNOON...WITH
A PRE-FRONTAL TROUGH DRAPED ACROSS THE CENTRAL PORTION OF THE STATE.
AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH THE SOUTHEAST TOWARD THE
ATLANTIC...THE FRONT WILL SLOWLY PUSH THROUGH THE STATE THROUGH
WEDNESDAY.

.PRIMARY HAZARDS...
THE MAIN HAZARDS ASSOCIATED WITH SEVERE THUNDERSTORMS THAT DEVELOP
WILL BE DAMAGING WINDS...AND POSSIBLY LARGE HAIL. OTHERWISE...GUSTY
WINDS...LIGHTNING...SMALL HAIL...AND LOCALLY HEAVY RAINFALL CAN BE
EXPECTED THIS AFTERNOON AND EVENING. THE BEST LOCATION FOR SEVERE
WEATHER IS SOUTH OF A LINE FROM HELEN TO ROME...AND NORTH OF A LINE
FROM LOUISVILLE TO COLUMBUS.

.DISCUSSION...
THE COLD FRONT MOVING INTO THE STATE WILL PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT THIS AFTERNOON. THIS...COMBINED WITH
UNSEASONABLY WARM TEMPERATURES...WILL HELP DESTABILIZE THE
ATMOSPHERE. CAPE VALUES SHOULD RANGE BETWEEN 750 AND 1000 DURING THE
AFTERNOON AND EVENING ACROSS PORTIONS OF NORTH AND CENTRAL GEORGIA.
THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE AFTERNOON AND EARLY
EVENING HOURS...WITH ISOLATED STORMS BECOMING SEVERE.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY...
THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY...AND AGAIN FRIDAY
THROUGH MONDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED THROUGH TONIGHT.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
305 PM EDT TUE APR 17 2012

GAZ030-031-171930-
305 PM EDT TUE APR 17 2012

...SIGNIFICANT WEATHER ADVISORY FOR 35 MPH WINDS IN POLK AND PAULDING
COUNTIES UNTIL 330 PM EDT...

AT 302 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER YORKVILLE...MOVING NORTHEAST AT 10 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE PEA SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 35 MPH AS IT MOVES ACROSS
POLK AND PAULDING COUNTIES THROUGH 330 PM EDT. SOME LOCATIONS IN THE
PATH OF THIS STORM INCLUDE UNION...YORKVILLE...VAN WERT...ROCKMART...
BRASWELL...BURNT HICKORY RIDGE AND ARAGON. HEAVY DOWNPOURS WILL CAUSE
PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3410 8507 3410 8505 3408 8504 3408 8479
      3383 8495 3386 8504 3390 8504 3390 8510
      3391 8515
TIME...MOT...LOC 1906Z 204DEG 11KT 3395 8501

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
310 PM EDT TUE APR 17 2012

GAZ008-015-171945-
310 PM EDT TUE APR 17 2012

...SIGNIFICANT WEATHER ADVISORY FOR 35 MPH WINDS IN UNION AND LUMPKIN
COUNTIES UNTIL 345 PM EDT...

AT 307 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER CAMP MERRILL...MOVING NORTHEAST AT 25 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE PEA SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 35 MPH AS IT MOVES ACROSS
UNION AND LUMPKIN COUNTIES THROUGH 345 PM EDT. SOME LOCATIONS IN THE
PATH OF THIS STORM INCLUDE CAMP MERRILL...GOOCH MOUNTAIN SHELTER...
HAWK MOUNTAIN SHELTER...SUCHES...GADDISTOWN...BLOOD MOUNTAIN
SHELTER...WOODS HOLE SHELTER...VOGEL STATE PARK...JONES CREEK AND
OWLTOWN. HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3481 8394 3481 8392 3478 8388 3456 8404
      3462 8418 3473 8410 3480 8410 3480 8413
      3481 8414 3489 8410
TIME...MOT...LOC 1911Z 208DEG 20KT 3468 8408