Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
805 PM EDT TUE MAY 21 2013

.PREV DISCUSSION... /ISSUED 314 PM EDT TUE MAY 21 2013/

SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
MODELS CONTINUE IN GOOD AGREEMENT THROUGH THE SHORT TERM. AIRMASS
SHOWERS/TSTORMS DEVELOPING ACROSS THE CWA...MAINLY ACROSS THE
EXTREME NORTH AND EASTERN PARTS OF THE CWA. THESE WILL DISSIPATE
SHORTLY AFTER SUNSET THIS EVENING. THERE IS A POSSIBILITY THAT THE
STORMS OVER NORTHWEST AL AND CENTRAL TN COULD MAKE IT TO EXTREME
NORTHWEST GA BEFORE DIMINISHING THIS EVENING. THE H5 RIDGE OVER THE
EASTERN U.S. WILL WEAKEN AS THE CENTRAL U.S. TROUGH MOVES INTO THE
MISSISSIPPI VALLEY. THIS WILL PUSH A COLD FRONT INTO THE TENNESSEE
VALLEY WEDNESDAY WHICH WILL BRING A BETTER CHANCE OF THUNDERSTORMS
TO THE CWA...MAINLY ACROSS NORTH GA. INSTABILITY INCREASES WEDNESDAY
ACROSS NORTH GA AND THIS COULD PRODUCE A FEW STRONG STORMS. GUIDANCE
TEMPS LOOK GOOD FOR TONIGHT...ALTHOUGH TRICKY FOR WEDNESDAY WITH
ADDITIONAL CLOUDS. WILL TREND TO THE COOLER SIDE OF GUIDANCE ACROSS
NORTH GA FOR HIGHS ON WEDNESDAY DUE TO INCREASED CLOUDS AND PRECIP.

17

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
BY WEDNESDAY EVENING...BOTH THE GFS AND ECMWF INDICATE THAT THE
FRONT WILL BE WEAKENING SIGNIFICANTLY. GFS REMAINS AB IT ON THE
STRONG SIDE WITH A SLIGHTLY MORE EAST WITH THE GREAT LAKES SURFACE
LOW. BOTH ARE TRANSITIONING THE UPPER LOW TO MORE OF A SHARP OPEN
TROUGH PHASING WITH THE LONGWAVE TROUGH IN CANADA. WEAK SHORTWAVE
OFF THE SOUTH CAROLINA COAST WILL LIFT NORTHEAST AND BE ABSORBED
BY THE LONGWAVE TROUGH AS WELL. SPC CONTINUES THE AREA IN GENERAL
THUNDER FOR THURSDAY...WITH MUCAPE VALUES 500-1000 J/KG EARLY IN
THE DAY...DECREASING BY MID-MORNING...AND INCREASING AGAIN IN
EXTREME SOUTHERN ZONES JUST AHEAD OF THE FRONT AFTER 18Z TO OVER
1000 J/KG. WILL HAVE TO MONITOR THE AREA FOR THE POTENTIAL FOR
ISOLATED STRONG STORMS BUT NOTHING TO SIGNIFICANT.

COLD FRONT SHOULD BE PUSHED THROUGH THE AREA BY LATE THURSDAY...
AND HAVE DECREASED TEMPS NORTHWEST SOMEWHAT TO LINE UP WITH THAT
TIMING A LITTLE BETTER. SHOULD SEE A SIGNIFICANT DECREASE IN TEMPS
TOWARD THE END OF THE WEEK WITH SURFACE HIGH PRESSURE BUILDING IN
AND NORTHWEST FLOW ALOFT...CURRENT FORECAST HAS HIGHS ON FRIDAY
ABOUT 5 DEGREES COOLER THAN HIGHS ON THURSDAY EXCEPT IN CENTRAL
GEORGIA. SEE PREVIOUS LONG TERM DISCUSSION BELOW.

TDP

&&

.AVIATION...
00Z UPDATE...
MOST OF THE SCATTERED CONVECTION AROUND ATL HAS DIED DOWN WITH
SUNSET...HOWEVER...OUTFLOW BOUNDARY WHICH SHOWS UP ON ATL TDWR AS
WELL AS BOUNDARY ON JGX RADAR NEAR MCN STILL INGNITING A FEW STORMS.
HAVE LEFT TS OUT FOR THE EVENING EXCEPT FOR ATL AND MCN WHICH
SHOULD GET A GLANCING BLOW OF THE CELLS IN EAST GA MOVING SW. HIGH
RES HRRR AND WRF INDICATING SOME DECENT STORM DEVELOPMENT AROUND
THE METRO ATL AIRPORTS BETWEEN 01Z AND 02Z ALONG THE WESTWARD
MOVING OUTFLOW BOUNDARY BUT NOT CONFIDENT ENOUGH IN THAT SCENARIO
TO INSERT INTO TAF...BUT WILL MONITOR FOR POSSIBLE AMD. HAVE
INTRODUCED PROB30 TO ALL TAF SITES TOMORROW AFTERNOON BETWEEN 19Z
AND 20Z AS 4 KM WRF SHOWING CONVECTIVE INITIATION AROUND THAT TIME
AS WEAK COLD FRONT AND REMNANT OUTFLOW MOVE INTO GA. WINDS SHOULD
GO GENERALLY CALM TONIGHT AND PICK UP OUT OF THE SSW BETWEEN 6 TO
10KTS AFTER AROUND 13Z WED.

//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON CONVECTION THIS EVENING.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.

KSTELLMAN

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          64  84  64  84 /  30  40  40  30
ATLANTA         67  83  66  82 /  20  40  40  30
BLAIRSVILLE     60  77  60  78 /  30  60  50  30
CARTERSVILLE    64  84  62  82 /  20  60  40  30
COLUMBUS        68  89  67  87 /  20  30  30  30
GAINESVILLE     65  83  64  81 /  20  50  40  30
MACON           63  87  65  86 /  20  30  30  30
ROME            64  84  61  83 /  30  60  40  30
PEACHTREE CITY  63  85  63  84 /  20  40  30  30
VIDALIA         68  89  69  88 /  40  30  30  30

&&

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

SHORT TERM...30
LONG TERM....SNELSON
AVIATION...SNELSON

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
740 PM EDT TUE MAY 21 2013

GAZ025-027-035>037-220030-
740 PM EDT TUE MAY 21 2013

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN OCONEE...MADISON...BARROW...CLARKE AND JACKSON COUNTIES UNTIL 830
PM EDT...

AT 738 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
CLUSTER OF STRONG THUNDERSTORMS DEVELOPING OVER CENTER...MOVING
NORTHEAST AT 5 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE DIME SIZED HAIL...
FREQUENT CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS THEY
SPREAD ACROSS OCONEE...MADISON...BARROW...CLARKE AND JACKSON
COUNTIES THROUGH 830 PM EDT. SOME LOCATIONS IN THE PATH OF THIS
STORM INCLUDE WESTGATE PARK...OCONEE HEIGHTS...BOGART...STATHAM...
BEAR CREEK RESERVOIR...ARCADE...JEFFERSON...JAMES HOLLAND YOUTH
SPORTS COMPLEX...APPLE VALLEY...CENTER...SANFORD...SANDY CREEK
RECREATION AREA...BARRETTS MILL...DIAMOND HILL AND NEESE.

HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3421 8342 3420 8341 3420 8340 3420 8337
      3406 8325 3386 8355 3404 8372 3422 8343
TIME...MOT...LOC 2339Z 239DEG 3KT 3404 8345

16

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
759 PM EDT TUE MAY 21 2013

GAZ060-061-072>074-083-084-220030-
759 PM EDT TUE MAY 21 2013

...SIGNIFICANT WEATHER ADVISORY FOR PEA SIZED HAIL AND 40 MPH WINDS
IN WASHINGTON...TWIGGS...PUTNAM...JONES...WILKINSON...BALDWIN AND
HANCOCK COUNTIES UNTIL 830 PM EDT...

AT 755 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
CLUSTER OF STRONG THUNDERSTORMS OVER MERIWETHER AND HARDWICK...MOVING
WEST AT 20 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 WASHINGTON...TWIGGS...PUTNAM...JONES...WILKINSON...BALDWIN
AND HANCOCK COUNTIES THROUGH 830 PM EDT. SOME LOCATIONS IN THE PATH
OF THIS STORM INCLUDE ALLENWOOD...HARDWICK...SCOTTSBORO...
UNDERWOOD...PANCRAS...MILLEDGEVIL LE...BEULAH...DEVEREUX...
COOPERS...PLANT HARLEE BRANCH...FLAT ROCK...MERIWETHER...BROWNS
CROSSING...HADDOCK AND RESSEAUS CROSSROADS.

HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3281 8349 3327 8355 3329 8354 3325 8307
      3285 8298
TIME...MOT...LOC 2357Z 089DEG 20KT 3314 8328

16

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
902 PM EDT TUE MAY 21 2013

GAZ035-220130-
902 PM EDT TUE MAY 21 2013

...SIGNIFICANT WEATHER ADVISORY FOR NICKEL SIZED HAIL AND 40 MPH
WINDS IN BARROW COUNTY UNTIL 930 PM EDT...

AT 859 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM CENTERED NEAR WINDER...MOVING NORTH AT 10 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE NICKEL SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS IT MOVES ACROSS
BARROW COUNTY THROUGH 930 PM EDT. SOME LOCATIONS IN THE PATH OF THIS
STORM INCLUDE FORT YARGO STATE PARK...RUSSELL...BETHLEHEM...WINDER...
CARL...AUBURN AND COUNTY LINE.

&&

LAT...LON 3408 8378 3407 8377 3406 8371 3405 8371
      3406 8370 3405 8369 3405 8365 3404 8363
      3392 8364 3391 8377 3405 8386 3407 8384
TIME...MOT...LOC 0102Z 175DEG 8KT 3398 8373

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
912 PM EDT TUE MAY 21 2013

GAZ058-071-220145-
912 PM EDT TUE MAY 21 2013

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN MONROE AND BUTTS COUNTIES UNTIL 945 PM EDT...

AT 908 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM CENTERED 2 MILES SOUTH OF FLOVILLA...MOVING
NORTHWEST AT 5 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE DIME SIZED HAIL...OCCASIONAL
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS IT MOVES ACROSS
MONROE AND BUTTS COUNTIES THROUGH 945 PM EDT. SOME LOCATIONS IN THE
PATH OF THIS STORM INCLUDE BLOUNT...FLOVILLA...INDIAN SPRINGS STATE
PARK...HIGH FALLS STATE PARK AND JACKSON.

&&

LAT...LON 3336 8399 3325 8383 3314 8389 3318 8404
      3320 8404 3320 8406
TIME...MOT...LOC 0109Z 124DEG 5KT 3322 8391

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