Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
803 PM EDT SAT MAY 5 2012

.PREV DISCUSSION... /ISSUED 341 PM EDT SAT MAY 5 2012/

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
MAIN FORECAST CONCERN WILL BE PRECIPITATION CHANCES EARLY TONIGHT
ASSOCIATED WITH SEVERAL BOUNDARIES... AND ALSO SUNDAY INTO SUNDAY
NIGHT WITH THE INFLUENCE OF A WEAK SURFACE FRONT AND UPPER LEVEL
SHORTWAVE. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH MAIN INFLUENCING
FEATURES.

FOR THIS EVENING INTO TONIGHT... PRECIP CHANCES AND TIMING REMAIN
TRICKY AS REMNANTS OF A MORNING MCS HAVE LEAD TO THE INFLUENCE OF
SEVERAL BOUNDARIES ACROSS OR NEAR THE FORECAST AREA. ONE BOUNDARY...
SITUATED ACROSS SOUTHEASTERN TN... HAS STRONGER BAROCLINITY DUE TO
SOLAR SHELTERING FROM THE REMNANT CLOUD DECK... AND THE REMNANT
OUTFLOW BOUNDARY HAS BEEN TRAVERSING SOUTHWARD ACROSS THE AREA WITH
LITTLE TO NO ASSOCIATED CONVECTIVE TRIGGERING SO FAR. WHILE
SHORT TERM GUIDANCE HAS FOCUSED ON THE NORTHEASTERN PORTION OF THE
FORECAST AREA FOR BEST CHANCE OF CONVECTIVE DEVELOPMENT DOWNSTREAM
OF THE AFOREMENTIONED NORTHERN BOUNDARY... THE CENTRAL PORTION OF
THE AREA IS INCLUDED IN A SLIGHT RISK FOR SEVERE STORMS. THIS RISK
IS FOCUSED ON THE INFLUENCE OF THE OUTFLOW BOUNDARY. ADDITIONALLY...
A THIRD BOUNDARY MOVING SLOWLY SOUTHEASTWARD ACROSS THE
SOUTHERN PART OF THE AREA HAS BEEN CAUSING SOME SCATTERED
THUNDERSTORM DEVELOPMENT... SOUTH OF THE SLIGHT RISK AREA. ALL
CONSIDERED HAVE DECIDED TO GO WITH WIDESPREAD CHANCE POPS INITIALLY
WITH THE BEST CHANCES IN THE SOUTH... AND THEN SLIGHT CHANCES AWAY
FROM THE SOUTH AFTER 21Z. THIS WILL NEED TO BE MONITORED FOR ANY
POTENTIAL UPDATES. AMPLE SBCAPE OF NEAR 3000 J/KG AND WEAK BULK
SHEAR OF LESS THAN 20 KTS LEAD TO THE MAIN CONVECTIVE THREAT BEING
PULSE STORMS WITH HAIL AND STRONG WIND POTENTIAL.

FOR SUNDAY AND SUNDAY NIGHT... A WEAK FRONT IS PROGGED TO DIP
SOUTHWARD ACROSS THE AREA IN THE MORNING HOURS AND THEN STALL OUT
NEAR THE SOUTHWESTERN PORTION DURING THE AFTERNOON. AN UPPER LEVEL
SHORTWAVE LOOKS TO ALSO SWING SOUTHEASTWARD ACROSS THE AREA NEAR
18Z... PROVIDING SOME ADDITIONAL FORCING FOR ASCENT. WITH THE
COMBINATION OF THESE FEATURES... HAVE DECIDED TO GO WITH LOW END
CHANCE POPS IN THE SOUTH AND WEST AFTER 15Z AND SLIGHT CHANCE POPS
ELSEWHERE. WILL GO FOR HIGHER POPS AND MORE WIDESPREAD AFTER 18Z
WITH INCREASED DIURNAL HEATING. THE SOUTHWESTERN MAJORITY OF THE
FORECAST AREA IS ALSO IN A SLIGHT RISK FOR SEVERE STORMS ON
SUNDAY... HOWEVER WEAK SHEAR AND MORE MODEST CAPE VALUES THAN
SATURDAY LOOK TO BE PRESENT.

TEMPS... HIGHS SEEM TO BE DOING WELL SO WENT CLOSE TO MAV AND BUMPED
UP OVERNIGHT LOWS AS RECENT MOS GUIDANCE HAS BEEN TRENDING TOO LOW.

03/49

LONG TERM /MONDAY THROUGH SATURDAY/...
WEAK RIDGING DOWN THE APPALACHIANS WILL BREAK DOWN AS HIGH PRESSURE
OVER THE MID ATLANTIC STATES MOVES INTO THE ATLANTIC ON MONDAY. WITH
CLOUD COVERAGE AND EFFECTS OF WEAK WEDGE RETREATING...HAVE DECIDED
TO STAY ON THE COOLER SIDE OF GUIDANCE FOR MONDAY. INCREASED RAIN
CHANCES WILL CONTINUE THROUGH MID-WEEK AS A FRONT MOVES THROUGH THE
CWA TUE-WED. INSTABILITY IS DECENT WITH THIS SYSTEM SO EXPECT
THUNDERSTORMS ASSOCIATED WITH THE FRONT...HOWEVER SHEAR IS BASICALLY
NON-EXISTENT. SLIGHT TIMING DIFFERENCES REMAIN IN WHEN THE FRONT
CLEARS OUT WITH THE 12Z GFS SOLUTION FASTER THAN THE 12Z ECMWF
/WEDNESDAY AFTERNOON VS. THURSDAY/. BY THE END OF THE LONG
TERM...THE NEXT SYSTEM WILL BE MOVING INTO THE LOWER MISSISSIPPI
VALLEY BUT PRECIP SHOULD HOLD OFF THROUGH SATURDAY AND 12Z ECMWF RUN
DOES NOT SHOW PRECIP ACROSS CWA LIKE THE PREVIOUS RUN DID. THE UPPER
LEVEL SYSTEM THOUGH ASSOCIATED WITH THIS SYSTEM THOUGH IS WEAKER IN
THE ECMWF AND THE SFC SYSTEM IS NOT RESOLVED LIKE IN THE GFS.

11

&&

.AVIATION...
00Z UPDATE...
ALTHOUGH CONDITIONS REMAIN TRANQUIL ACROSS THE AREA...WRF MODELS
CONTINUE TO INDICATE THE POSSIBILITY OF LATE EVENING DEVELOPMENT
FROM NORTH ALABAMA THROUGH NORTH GEORGIA. LATEST RADAR CONFIRMS
THIS BUT NOT ENOUGH EVIDENCE THUS FAR TO INCLUDE ANY SHORT TERM
TEMPO GROUPS. LIMITED CONVECTION SUNDAY AS WELL BUT WITH 30 POPS
IN GRIDS...HAVE GONE WITH PROB30 FOR THE AFTERNOON HOURS FOR ALL
TERMINALS.

//ATL CONFIDENCE...00Z UPDATE...
HIGH CONFIDENCE MOST ELEMENTS...EXCEPT MEDIUM CONFIDENCE ON
CONVECTION THIS AFTERNOON.

DEESE

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          64  87  61  81 /  20  30  20  30
ATLANTA         69  87  66  81 /  20  30  20  40
BLAIRSVILLE     60  83  60  77 /  30  30  20  40
CARTERSVILLE    62  89  61  81 /  20  30  20  40
COLUMBUS        68  91  66  83 /  20  40  30  40
GAINESVILLE     65  85  63  79 /  20  30  20  40
MACON           65  90  64  83 /  20  40  30  40
ROME            65  91  63  81 /  20  30  20  50
PEACHTREE CITY  63  88  62  81 /  20  40  20  40
VIDALIA         70  89  67  84 /  30  40  30  40

&&

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

SHORT TERM...DEESE
LONG TERM....BELANGER
AVIATION...DEESE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1100 AM EDT SAT MAY 5 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-061000-
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-
1100 AM EDT SAT MAY 5 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT...
SCATTERED THUNDERSTORMS WITH ISOLATED SEVERE STORMS POSSIBLE
THIS AFTERNOON AND EVENING ACROSS NORTH AND CENTRAL GEORGIA.

.SYNOPSIS...
AN AREA OF HIGH PRESSURE IN THE ATLANTIC WILL ALLOW GULF MOISTURE TO
FLOW INTO NORTH AND CENTRAL GEORGIA WHILE UPPER LEVEL DISTURBANCES
RIPPLE THROUGH THE AREA.

.PRIMARY HAZARDS...
THE PRIMARY HAZARDS WITH ANY SEVERE STORM WILL BE WIND GUSTS OF 60
MPH...QUARTER SIZED HAIL AND OCCASIONAL LIGHTNING. THE BEST CHANCE
OF STORMS WILL GENERALLY BE FROM 2 PM TO 10 PM.

.DISCUSSION...
AVAILABLE GULF MOISTURE AND INSTABILITY...WITH MUCAPE VALUES NEAR
3000 J/KG THIS AFTERNOON...ALONG WITH MULTIPLE BOUNDARIES ACROSS THE
AREA...WILL COMBINE TO PRODUCE THE POSSIBILITY OF THUNDERSTORMS THIS
AFTERNOON AND EVENING ACROSS NORTH AND CENTRAL GEORGIA. SOME OF
THESE STORMS MAY BECOME SEVERE.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...
THUNDERSTORMS ARE POSSIBLE SUNDAY THROUGH WEDNESDAY. STRONG
THUNDERSTORMS ARE POSSIBLE ON SUNDAY. NO HAZARDOUS WEATHER IS
EXPECTED ON THURSDAY OR FRIDAY AT THIS TIME.

.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
902 PM EDT SAT MAY 5 2012

GAZ052-060130-
902 PM EDT SAT MAY 5 2012

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL IN HEARD COUNTY
UNTIL 930 PM EDT...

AT 856 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER WARESVILLE ALABAMA...MOVING SOUTHEAST AT 10
MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE DIME SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 35 MPH AS IT MOVES ACROSS
HEARD COUNTY THROUGH 930 PM EDT. SOME LOCATIONS IN THE PATH OF THIS
STORM INCLUDE WARESVILLE AND GLENN. HEAVY DOWNPOURS WILL CAUSE
PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3318 8511 3316 8513 3312 8524 3313 8525
      3325 8527 3329 8527
TIME...MOT...LOC 0101Z 313DEG 10KT 3324 8530