Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1011 PM EDT FRI MAR 23 2012

.UPDATE...
AREA OF SHOWERS AND THUNDERSTORMS PUSHING EAST INTO SOUTH CAROLINA
AT THE MOMENT...BUT WATCHING AN AREA OF SHOWERS/THUNDERSTORMS
DEVELOP OVER NORTHEAST ALABAMA INTO EAST TENNESSEE. MODELS SIMILAR
WITH CONVECTION SPREADING ACROSS NORTHWEST GEORGIA SECOND HALF OF
THE NIGHT SO CHANCE TO GOOD CHANCE POPS NORTHERN HALF OF STATE
STILL LOOK IN LINE. ACROSS CENTRAL GEORGIA...COULD STILL SEE
ISOLATED TO WIDELY SCATTERED ACTIVITY SO WILL CONTINUE LOW CHANCE
POPS THERE. OTHERWISE...ONLY MINOR ADJUSTMENT NEEDED TO SKY AND TEMPS.

49
&&

.PREV DISCUSSION... /ISSUED 758 PM EDT FRI MAR 23 2012/

PREV DISCUSSION... /ISSUED 316 PM EDT FRI MAR 23 2012/

SHORT TERM /TONIGHT THROUGH SUNDAY/...
AN UPPER LEVEL LOW AND PLENTY OF AVAILABLE DEEP MOISTURE MAKE FOR AN
INTERESTING FEW DAYS IN NORTH AND CENTRAL GEORGIA. AS THE 500MB LOW
NEARS THE CWA...WE CAN EXPECT THUNDERSTORM ACTIVITY FRIDAY EVENING INTO
LATE SATURDAY NIGHT.

12Z FFC SOUNDING SAMPLES A MOIST ATMOSPHERE WITH 1.38 INCHES OF
PRECIPITABLE WATER...AROUND THE 95TH PERCENTILE FOR LATE MARCH. CSG
HAS SEEN 1.23 INCHES OF RAIN IN THE LAST 24 HOURS. RAINFALL SHOULD
BE MOSTLY BENEFICIAL...ALTHOUGH AN AREA THAT SEES SUSTAINED HEAVY
RAINFALLS COULD SEE FLOODING ISSUES.

FRIDAY AFTERNOON AND EVENING HAS A CHANCE FOR SOME
THUNDERSTORMS...WITH POCKETS OF INSTABILITY AVAILABLE TO PRODUCE A
HAIL AND WIND THREAT. 12Z FFC SOUNDING CAPE WAS 1260 J/KG WHILE
THE 12Z GFS AND 12Z NAM BRING 1700-2700 J/KG MUCAPES INTO PARTS OF
CENTRAL AND NORTH CENTRAL GEORGIA THIS AFTERNOON. TORNADO THREAT
CANNOT BE RULED OUT AS INDIVIDUAL STORMS COULD ENTER 20-25KT SHEAR
ENVIRONMENTS WHERE A QUICK SPIN-UP IS NOT IMPOSSIBLE.

AS THE FRONT FINALLY CLEARS THROUGH THE CWA ON SATURDAY...THE THREAT
OF THUNDERSTORMS WILL REMAIN WITH THE CONTINUED AVAILABILITY OF
MOISTURE AND UPPER LEVEL SUPPORT FROM THE 500MB LOW EXPECTED TO DIP
DOWN INTO THE STATE ON SATURDAY. POSSIBLE AIDS TO CONVECTION ON
SATURDAY INCLUDE STEEPER LAPSE RATES AS COOLER AIR ALOFT MOVES IN
WITH THE 500MB LOW AND FORCING FROM THE PASSING COLD FRONT.

12Z GFS MODEL GUIDANCE WAS MOVING RAIN OUT OF THE CWA QUICKLY ON
SATURDAY AND DECIDED TO SLOW DOWN EXIT OF PRECIPITATION. UPPER LEVEL
LOW CANNOT BE IGNORED AS A POSSIBLE WAY TO SQUEEZE EXTRA MOISTURE
OUT AND THE FRONTAL PASSAGE WILL LIKELY BE ABLE TO PRODUCE SOME RAIN
AS WELL.

SUNDAY SHOULD SEE CLEARING AND A RETURN TO MORE APPROPRIATE
SEASONAL TEMPERATURES. TEMPERATURES WERE GENERALLY SLIGHT
ADJUSTMENTS TO A MODEL BLEND OR A BIAS ADJUSTMENT OF THE MAV.

10

PREV DISCUSSION...

LONG TERM /SUNDAY THROUGH THURSDAY/...
/ISSUED 434 AM EDT FRI MAR 23 2012/
BY SUNDAY MORNING...THE CLOSED UPPER LOW IS EAST OF THE AREA AND
OVER THE CAROLINAS. COLD POOL ALOFT WITH 500 TEMPS AROUND -22C
SHOULD KEEP LAPSE RATES ELEVATED...BUT STRONG DIFFLUENT PATTERN
SHOULD MORE THAN OFFSET THIS AND WILL JUST CARRY 20 POPS OR LESS
FOR EASTERN SECTIONS THROUGH SUNDAY EVENING. DECENT DRY SPELL
THEREAFTER AS MID AND UPPER LEVEL RIDGE BUILD BACK IN THROUGH
EARLY NEXT WEEK. NEXT FRONTAL BOUNDARY FOR WED INTO THU LOOKS TO
STALL OUT NORTH OF THE AREA WITH VERY LOW END POPS TO BE CARRIED
FOR THE EXTREME NORTHERN TIER. TEMPS LOOK TO MODERATE ONCE AGAIN
THROUGH THE PERIOD WITH SOME LOWER 80S LIKELY TOWARD THE END OF
THE WORK WEEK.

23

HYDROLOGY...
/ISSUED 434 AM EDT FRI MAR 23 2012/
GENERALLY EXPECTING AROUND A HALF INCH TO AN INCH OF RAIN WITH
THIS SYSTEM THROUGH SATURDAY NIGHT. FFG VALUES ARE AROUND 2-4
INCHES SO OVERALL SHOULD BE ABLE TO HANDLE THE RAINFALL.

11

AVIATION...
00Z UPDATE...
SHOWERS ENDING ACROSS THE AREA BUT A SECOND LINE OF THUNDERSTORMS
IN EXPECTED TO MOVE ACROSS THE STATE LATE TONIGHT THROUGH SAT
AFTERNOON. THIS LINE SHOULD MOVE SOUTHEAST ACROSS THE ATL AREA TAF
SITES BETWEEN 9Z-14Z. WINDS WILL STAY OUT OF THE W-SW THROUGH THE
PERIOD IN THE 5-10KT RANGE. WINDS MAY BE A BIT GUSTY AND VARIABLE
IN AND AROUND TSRA DEVELOPMENT.VSBYS SHOULD STAY VFR. CEILINGS
WILL BE UP AND DOWN BUT MAINLY IN THE MVFR RANGE. MAY SE SOME
BRIEF PERIODS OF IFR CEILINGS AS TSRA MOVES IN OVER NIGHT BUT
SHOULD BE SHORT LIVED.

//ATL CONFIDENCE...00Z UPDATE...
CONFIDENCE IS MEDIUM ON ALL ELEMENTS.

01

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          58  77  51  76 /  80  70  30  20
ATLANTA         59  75  53  72 /  60  40  30   5
BLAIRSVILLE     53  70  47  70 /  60  40  30  10
CARTERSVILLE    53  75  49  74 /  60  40  30   5
COLUMBUS        61  79  56  77 /  60  70  20   5
GAINESVILLE     56  75  51  73 /  70  40  30  20
MACON           60  79  52  76 /  70  60  30  10
ROME            53  75  50  75 /  60  40  30   5
PEACHTREE CITY  58  76  48  76 /  60  50  30   5
VIDALIA         62  81  56  79 /  80  80  30  20

&&

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

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
821 PM EDT FRI MAR 23 2012

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-241200-
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-
821 PM EDT FRI MAR 23 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...TONIGHT...
ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED.

.SYNOPSIS...
A STRONG UPPER LEVEL SYSTEM WILL CONTINUE TO PUSH ACROSS THE MISSOURI
VALLEY TONIGHT AS THE ASSOCIATED SURFACE LOW LIFTS NORTH INTO THE
OHIO VALLEY.

.PRIMARY HAZARDS...
THE PRIMARY HAZARDS FROM ANY THUNDERSTORM TONIGHT WILL BE
FREQUENT LIGHTNING...GUSTY WINDS AND LOCALLY HEAVY RAIN.

.DISCUSSION...
SHOWERS AND SCATTERED THUNDERSTORMS ASSOCIATED WITH THE UPPER LOW
AND THE SURFACE LOW PRESSURE SYSTEM WILL CONTINUE TO SPREAD
ACROSS THE SOUTHEAST STATES OVERNIGHT. WITH THE LOSS OF DAYTIME
HEATING STORMS ARE EXPECTED TO STAY BELOW SEVERE LIMITS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY...
THERE IS A CHANCE OF THUNDERSTORMS SATURDAY THROUGH SUNDAY...AND
WEDNESDAY THROUGH THURSDAY.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1222 AM EDT SAT MAR 24 2012

GAZ001-240515-
1222 AM EDT SAT MAR 24 2012

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN DADE COUNTY UNTIL 115 AM EDT...

AT 1217 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 10 MILES WEST OF STEPHENSVILLE...MOVING NORTHEAST
AT 35 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE DIME SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS THEY MOVE
ACROSS DADE COUNTY THROUGH 115 AM EDT. SOME LOCATIONS IN THE PATH OF
THESE STORMS INCLUDE STEPHENSVILLE...TRENTON...NEW ENGLAND...COLE
CITY...MORGANVILLE...HOOKER AND WILDWOOD. HEAVY DOWNPOURS WILL CAUSE
PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3499 8538 3474 8556 3475 8557 3486 8559
      3498 8561 3499 8560
TIME...MOT...LOC 0423Z 233DEG 31KT 3488 8568

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1252 AM EDT SAT MAR 24 2012

GAZ001-002-240530-
1252 AM EDT SAT MAR 24 2012

...SIGNIFICANT WEATHER ADVISORY FOR PENNY SIZED HAIL AND 50 MPH WINDS
IN WALKER AND DADE COUNTIES UNTIL 130 AM EDT...

AT 1245 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 10 MILES SOUTHWEST OF RISING FAWN...MOVING EAST
AT 30 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE PENNY SIZED HAIL...
FREQUENT CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 50 MPH AS THEY
MOVE ACROSS WALKER AND DADE COUNTIES THROUGH 130 AM EDT. SOME
LOCATIONS IN THE PATH OF THESE STORMS INCLUDE RISING FAWN...CLOUDLAND
CANYON STATE PARK...CEDAR GROVE...CEDAR GROVE...COOPER HEIGHTS...
LAFAYETTE AND LINWOOD. HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON
ROADWAYS.

&&

LAT...LON 3490 8531 3463 8519 3461 8554 3479 8558
TIME...MOT...LOC 0452Z 256DEG 26KT 3467 8560

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
101 AM EDT SAT MAR 24 2012

GAZ011-019-240545-
101 AM EDT SAT MAR 24 2012

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN CHATTOOGA AND FLOYD COUNTIES UNTIL 145 AM EDT...

AT 1254 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 7 MILES SOUTHWEST OF CHATTOOGAVILLE...MOVING
NORTHEAST AT 30 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE DIME SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS THEY MOVE
ACROSS CHATTOOGA AND FLOYD COUNTIES THROUGH 145 AM EDT. SOME
LOCATIONS IN THE PATH OF THESE STORMS INCLUDE CHATTOOGAVILLE...
COOSA...LYERLY...HOLLAND...BERRYTON...JAMES H. FLOYD STATE PARK...
TIDINGS AND ARMUCHEE. HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON
ROADWAYS.

&&

LAT...LON 3457 8520 3434 8507 3418 8544 3421 8546
      3436 8549 3439 8549
TIME...MOT...LOC 0501Z 237DEG 27KT 3429 8546

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
128 AM EDT SAT MAR 24 2012

GAZ001>004-240615-
128 AM EDT SAT MAR 24 2012

...SIGNIFICANT WEATHER ADVISORY FOR DIME SIZED HAIL AND 40 MPH WINDS
IN WHITFIELD...WALKER...CATOOSA AND DADE COUNTIES UNTIL 215 AM EDT...

AT 120 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER CEDAR GROVE...MOVING EAST AT 25 MPH.

THESE STORMS HAVE THE POTENTIAL TO PRODUCE DIME SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS THEY MOVE
ACROSS WHITFIELD...WALKER...CATOOSA AND DADE COUNTIES THROUGH 215 AM
EDT. SOME LOCATIONS IN THE PATH OF THESE STORMS INCLUDE CEDAR
GROVE...COOPER HEIGHTS...LAFAYETTE...LINWOOD...NAOMI...CHICKAMAUGA...
NOBLE...ROCK SPRING...BLUE SPRING...BEAUMONT...BOYNTON...WOOD
STATION...INDIAN SPRINGS...MILL CREEK AND RINGGOLD. HEAVY DOWNPOURS
WILL CAUSE PONDING OF WATER ON ROADWAYS.

&&

LAT...LON 3499 8513 3472 8498 3463 8540 3479 8547
TIME...MOT...LOC 0529Z 251DEG 21KT 3473 8535