Severe Thunderstorm Warning 328, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED FOR AVIATION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
524 PM EDT FRI JUN 23 2006

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
UPPER RIDGE CONTINUES TO WEAKEN AND SPLITTING INTO TWO CENTERS...ONE
OFF THE ATLANTIC COAST AND ANOTHER OVER THE WESTERN STATES...LEAVING
A WEAKNESS IN THE RIDGE OVER THE MID-SOUTH AND SOUTHEAST. SFC
PATTERN IS WEAK AND DIFFUSE...DRIVEN LARGELY BY CONVECTIVE OUTFLOW
BOUNDARIES. MEANWHILE...AN UPPER TROUGH IS DEEPENING OVER THE OHIO
VALLEY. TO FURTHER COMPLICATE THE PICTURE...A PSEUDO TROPICAL
SFC/UPPER LOW OFF THE EAST COAST OF FLORIDA WILL DRIFT W-NW AROUND
THE BACK SIDE OF THE MID-ATLANTIC SUBTROPICAL HIGH. THIS WILL ALL
RESULT IN A VERY WET PATTERN FOR GA AND THE SE STATES THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. FOR THIS AFTERNOON AND
TONIGHT...BEST AREA OF INSTABILITY AND MOISTURE CONVERGENCE IS
ACROSS NW GA BACK INTO AL. DYNAMICS ARE ALSO BEST IN THIS AREA WITH
SLIGHT SUBSIDENCE NOTED OVER THE SOUTHEAST AREAS IN RESPONSE TO
DEVELOPING TROPICAL LOW. CAPES FORECAST IN EXCESS OF 3000 AND LIS TO
-4 ACROSS MUCH OF N GA THROUGH THE EVENING. TYPICAL PULSE SEVERE
LIKELY WITH COVERAGE OVERALL GREATER THAN THU AND LIKELY LINGERING
LONGER INTO THE EVENING HOURS THAN THU AS WELL. 12Z FFC SOUNDING
SHOWS ENTIRE ATMOSPHERIC COLUMN MUCH MORE SATURATED THAN
YESTERDAY...BUT HAS COOLED SEVERAL DEGREES AT 500MB.  THIS WILL
RESULT IN INCREASED THREAT FOR HAIL...BUT DECREASED THREAT FOR
DAMAGING WINDS. IN ADDITION...WITH AN INCREASINGLY TROPICAL AIR MASS
IN PLACE...LOCALLY HEAVY RAIN WILL BE A THREAT. FOR NOW...THIS
SHOULD NOT BE A PROBLEM WITH A DRY AIR MASS IN PLACE. WIDESPREAD
HEAVY RAINFALL IS NOT EXPECTED WITH ACTIVITY TODAY OR SATURDAY. FOR
TEMPERATURES...THIS SHOULD BE THE LAST DAY OF REALLY HOT
TEMPERATURES AS FINAL DAY OF +20C AT 850MB. GENERALLY +18C
SAT-SUN...FINALLY COOLING TO AROUND +16C BY TUE. NEW MAV MOS TEMPS
LOWERS MAX TEMPS FOR MOST AREAS TO THE 88-92 DEGREE RANGE FOR THE
WEEKEND. SAT APPEARS TO BE VERY SIMILAR TO TODAY...WITH A SLIGHT
INCREASE IN AREAL COVERAGE POSSIBLE. BY SUN...HOWEVER...DEEPER
TROPICAL MOISTURE BEGINS TO FEED INTO THE AREA FROM THE SE. THIS
COMBINED WITH THE UPPER TROUGH APPROACHING FROM THE NW AND A WEAK
SFC BOUNDARY SAGGING INTO THE AREA FROM THE NW WILL SERVE TO ENHANCE
SHRA/TSRA ACTIVITY WITH AN INCREASING THREAT OF HEAVY RAIN AS WELL.
ZONES HAVE BEEN WORDED ACCORDINGLY.

.LONG TERM...(MONDAY THROUGH FRIDAY)
NAM AND GFS IN GOOD AGREEMENT. MON APPEARS TO BE A VERY WET DAY.
TROPICAL UPPER/SFC LOW DRIFTS N THROUGH EAST GEORGIA.
MEANWHILE...UPPER TROUGH DEEPENS INTO THE SOUTHEAST AND TAKES ON THE
FORM OF A FULL LATITUDE TROUGH...RATHER UNUSUAL FOR LATE JUNE. THIS
PATTERN SHOULD SERVE TO BRING HEAVY RAIN AND THUNDERSTORMS TO MUCH
OF GEORGIA...ESPECIALLY THE EASTERN SECTIONS. HAVE ADDED MENTION OF
HEAVY RAINS AND INCREASED POPS TO LIKELY FOR MON. HOWEVER...BEYOND
THIS...GFS ADVERTISING A MUCH DRIER PATTERN...BUT CONSISTENT WITH
THE PAST TWO RUNS. IF PATTERN EVOLVES AS EXPECTED WITH UPPER TROUGH
AXIS MOVING EAST OF THE AREA LATE TUE AND TROPICAL LOW MOVING UP THE
COAST...VERY DRY AIR WILL ADVECT INTO THE AREA FROM THE W AND NW. AS
A RESULT...HAVE REMOVED MENTION OF POPS FOR THE WED-THU PERIOD. BY
FRI...NW FLOW BRINGS A DISTURBANCE TO THE AREA WITH THE POTENTIAL
FOR SHRA/TSRA IN THE NORTHERN ZONES ESPECIALLY. TEMPERATURES WILL
COOL TO NEAR SEASONAL NORMALS THROUGH THE PERIOD. EARLY IN THE
EXTENDED...WED-THU...MORNING LOWS WILL ACTUALLY BE BELOW NORMAL AS
DRY AIR ADVECTS INTO THE AREA FROM THE WEST.

&&

.AVIATION...
A LINE OF STORMS PUSHING INTO NORTHWEST GEORGIA FROM ALABAMA IS
WEAKENING SLIGHTLY...BUT STILL EXPECTED TO HOLD TOGETHER ENOUGH TO
BRING A THREAT OF TSTMS TO THE RYY...PDK...FTY...AND ATL AIRPORTS
THIS EVENING...AN ESTIMATE OF TIMING WOULD BE APPROACHING THE
AIRPORTS BY 7-8 PM...WITH TEMPO TSTMS POSSIBLE THRU 11-MIDNIGHT.
LATEST SURFACE ANALYSIS SHOWS A WEAK SURFACE TROUGH ACROSS NORTH
GA...WHICH SHOULD HELP MAINTAIN THE LINE AS IT PUSHES
EASTWARD...WITH SOME DEVELOPMENT EXPECTED ALONG ITS SOUTHERN
PERIPHERY. OUT AHEAD OF THIS LINE...WILL CONTINUE TO SEE ISOLATED
TSTM DEVELOPMENT THRU THE EARLY EVENING HEATING. THE MAIN THREAT
FROM THESE TSTMS WOULD BE TEMPO LOW CIGS OF 500-800 FT AND WIND
GUSTS TO 45 MPH. OTHERWISE...EXPECT CONVECTION THREAT TO DISSIPATE
AROUND THE AIRPORTS BY MIDNIGHT...WITH POSSIBLY SOME PATCHY FOG
DEVELOPING TOWARD MORNING...ESPECIALLY FOR RAIN SOAKED AREAS. LIGHT
AND VARIABLE WINDS TONIGHT WILL BECOME MORE SELY AT 5-10KTS AROUND
15-21Z SAT...THEN POSSIBLY BECOMING MORE NORTHERLY AFTER 21Z SAT AS
A WEAK FRONTAL BOUNDARY/SURFACE TROUGH PUSHES INTO CENTRAL GA.  /39

&&

.PRELIMINARY POINT TEMPS/POPS...
ATLANTA         72  89  71  86 /  50  40  30  50
ATHENS          70  92  68  87 /  50  40  30  60
GAINESVILLE     70  86  68  83 /  60  50  40  60
ROME            71  93  70  89 /  40  50  30  50
COLUMBUS        73  95  73  89 /  30  30  30  50
MACON           70  95  70  91 /  30  30  20  50

&&

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

19

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
432 PM EDT FRI JUN 23 2006

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-240900-
DADE-WALKER-CATOOSA-WHITFIELD-MURRAY-FANNIN-GILMER-UNION-TOWNS-
CHATTOOGA-GORDON-PICKENS-DAWSON-LUMPKIN-WHITE-FLOYD-BARTOW-
CHEROKEE-FORSYTH-HALL-BANKS-JACKSON-MADISON-POLK-PAULDING-COBB-
NORTH FULTON-GWINNETT-BARROW-CLARKE-OCONEE-OGLETHORPE-WILKES-
HARALSON-CARROLL-DOUGLAS-SOUTH FULTON-DEKALB-ROCKDALE-WALTON-
NEWTON-MORGAN-GREENE-TALIAFERRO-HEARD-COWETA-FAYETTE-CLAYTON-
SPALDING-HENRY-BUTTS-JASPER-PUTNAM-HANCOCK-WARREN-TROUP-
MERIWETHER-PIKE-UPSON-LAMAR-MONROE-JONES-BALDWIN-WASHINGTON-
GLASCOCK-JEFFERSON-HARRIS-TALBOT-TAYLOR-CRAWFORD-BIBB-TWIGGS-
WILKINSON-JOHNSON-EMANUEL-MUSCOGEE-CHATTAHOOCHEE-MARION-SCHLEY-
MACON-PEACH-HOUSTON-BLECKLEY-LAURENS-TREUTLEN-STEWART-WEBSTER-
SUMTER-DOOLY-CRISP-PULASKI-WILCOX-DODGE-TELFAIR-WHEELER-
MONTGOMERY-TOOMBS-
432 PM EDT FRI JUN 23 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...REST OF THIS AFTERNOON AND TONIGHT.
ISOLATED SEVERE THUNDERSTORMS CONTINUE TO BE EXPECTED ACROSS NORTH
AND PORTIONS OF CENTRAL GEORGIA LATE THIS AFTERNOON AND EVENING.

.SYNOPSIS...
HIGH PRESSURE ALOFT CONTINUES TO WEAKEN AS A WEAK UPPER LEVEL TROUGH
APPROACHES FROM THE WEST. A SURFACE TROUGH OF LOW PRESSURE HAS
ALREADY DEVELOPED ACROSS NORTH GEORGIA AND WILL HELP PROVIDE THE
FOCUS FOR SCATTERED THUNDERSTORMS DURING MAX HEATING THIS AFTERNOON
AND EVENING.

.PRIMARY HAZARDS...
THE PRIMARY HAZARD FROM ANY SEVERE THUNDERSTORMS WILL BE DAMAGING
WINDS AND LARGE HAIL. FREQUENT LIGHTNING CAN ALSO BE EXPECTED WITH
ANY STRONG THUNDERSTORMS. THE MOST LIKELY LOCATION FOR SEVERE
THUNDERSTORMS WILL BE ALONG AND NORTH OF A CARROLLTON TO ATLANTA TO
ATHENS LINE...ALTHOUGH AN ISOLATED STRAY SEVERE STORM IS DEFINITELY
POSSIBLE JUST SOUTH OF THAT LINE...ESPECIALLY DURING MAX DAYTIME
HEATING. SOME THUNDERSTORMS COULD LINGER UNTIL AFTER MIDNIGHT.

.DISCUSSION...
WITH PLENTY OF MOISTURE IN PLACE...THE AIRMASS HAS BECOME MODERATELY
UNSTABLE THIS AFTERNOON...WITH CAPES OF 1500 TO 2500 AND LIFTED
INDICES OF MINUS 4 TO MINUS 8. A SURFACE TROUGH ACROSS NORTH GEORGIA
WILL INTERACT WITH DAYTIME HEATING TO AID THUNDERSTORM DEVELOPMENT
LATE THIS AFTERNOON THROUGH THE EVENING HOURS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.
THUNDERSTORMS WILL BE POSSIBLE EACH DAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTERS SHOULD REMAIN ALERT FOR POSSIBLE ACTIVATION THIS AFTERNOON.
EMERGENCY MANAGERS SHOULD MONITOR THE SITUATION.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
424 PM EDT FRI JUN 23 2006

GAZ027-038-232115-
424 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR PEA SIZED HAIL AND FREQUENT
LIGHTNING IN OGLETHORPE AND MADISON COUNTIES UNTIL 515 PM EDT...

AT 422 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS DEVELOPING FROM PAOLI...TO COMER...TO
LEXINGTON...DRIFTING NORTHEAST AT 10 MPH.

LIGHTNING DETECTION SYSTEMS INDICATE NUMEROUS CLOUD-TO-GROUND
LIGHTNING STRIKES WITH THIS ACTIVITY. RESIDENTS IN THIS AREA SHOULD
STAY INDOORS. ELECTRICAL APPLIANCES AND TELEPHONES SHOULD NOT BE
USED UNLESS IN AN EMERGENCY.

SIGNIFICANT WEATHER ALERTS ARE ISSUED WHEN WINDS UP TO 57 MPH ARE
EXPECTED...HAIL IS EXPECTED TO BE LESS THAN THE SIZE OF PENNIES...OR
SIGNIFICANT CLOUD-TO-GROUND LIGHTNING IS EXPECTED.

19

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
440 PM EDT FRI JUN 23 2006

GAZ016-232200-
440 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR RUNOFF IN THE MOUNTAINS DUE TO
PREVIOUS HEAVY RAIN IN WHITE COUNTY UNTIL 600 PM EDT...

AT 430 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS WITH HEAVY RAIN WERE MOVING OUT OF WHITE INTO RABUN
AND HABERSHAM COUNTIES. THE STORMS WERE MOVING TO THE NORTHEAST AT 5
TO 10 MPH.

THE RUNOFF FROM THESE STORMS WILL CAUSE SMALL CREEKS AND STREAMS TO
REACH BANKFULL AND RAPIDLY FLOW SOUTH TO THE CHATTAHOOCHEE RIVER AT
HELEN. THE RIVER STAGE ON THE CHATTAHOOCHEE RIVER AT HELEN AT 4 PM
EDT WAS AT 0.9 FEET AND RISING. FLOOD STAGE IS 6 FEET. THE RIVER
WILL CONTINUE TO RISE RAPIDLY 2 OR 3 MORE FEET DURING NEXT NEXT HOUR
OR TWO...BUT SHOULD NOT REACH FLOOD STAGE.

MOTORISTS ARE URGED TO AVOID PONDING WATER ON ROADS AND LOW WATER
CROSSINGS UNTIL THE FLOW DIMINISHES.

16

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
448 PM EDT FRI JUN 23 2006

GAZ011-019-030-041-232145-
448 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR HALF INCH HAIL AND 50 MPH WINDS
IN HARALSON...POLK...FLOYD AND CHATTOOGA COUNTIES UNTIL 545 PM EDT...

AT 447 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF STRONG THUNDERSTORMS FROM MENLO TO 19 MILES WEST OF
TALLAPOOSA...MOVING EAST AT 20 MPH.

WIND GUSTS OF 50 MPH ARE POSSIBLE AS THESE STORMS MOVE INTO THESE
COUNTIES FROM ALABAMA. A FEW TREES OR LARGE TREE LIMBS MAY FALL. BE
PREPARED FOR POSSIBLE POWER OUTAGES. SMALL HAIL UP TO ABOUT A HALF
INCH IN DIAMETER IS POSSIBLE WITH THE STRONGEST STORMS.

RESIDENTS OF HARALSON...POLK...FLOYD AND CHATTOOGA COUNTIES SHOULD
BE PREPARED TO MOVE INDOORS AS THESE STORMS APPROACH.

15

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
525 PM EDT FRI JUN 23 2006

GAZ014-015-023-232215-
525 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR PEA SIZED HAIL AND 45 MPH WINDS IN
HALL...DAWSON AND LUMPKIN COUNTIES UNTIL 615 PM EDT...

AT 520 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 6 MILES WEST OF MURRAYVILLE...MOVING NORTHEAST AT
10 MPH.  THIS STORM WILL MOVE OVER THE NORTHERN PARTS OF LAKE LANIER.

EXPECT FREQUENT LIGHTNING...WIND GUSTS TO 45 MPH AND BRIEF HEAVY
DOWNPOURS ACROSS NORTHERN HALL...DAWSON...AND LUMPKIN COUNTIES.
BOATERS ON LAKE LANIER SHOULD SEEK SAFE HARBOR NOW. GET OFF OF THE
WATER IMMEDIATELY AND WAIT UNTIL THE STORMS HAVE COMPLETELY PASSED
BEFORE RETURNING TO THE LAKE.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
532 PM EDT FRI JUN 23 2006

GAZ031-042-232215-
532 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR 50 MPH WINDS IN CARROLL AND
PAULDING COUNTIES UNTIL 615 PM EDT...

AT 529 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM 6 MILES NORTHWEST OF BOWDON TO 8 MILES
NORTHWEST OF BRASWELL...MOVING EAST AT 20 MPH.

WIND GUSTS OF 50 MPH ARE POSSIBLE AHEAD OF THESE STORMS AS THEY MOVE
TOWARD CARROLL AND PAULDING COUNTIES FROM THE WEST. THESE WINDS MAY
CAUSE DAMAGE TO A FEW TREES OR LARGE TREE LIMBS. HAIL UP TO A HALF
INCH IN DIAMETER IS ALSO POSSIBLE WHEN THE STORMS ARRIVE.

RESIDENTS OF CARROLL AND PAULDING COUNTIES SHOULD BE PREPARED TO
MOVE INDOORS AS THESE STORMS APPROACH. ALSO BE PREPARED FOR POSSIBLE
POWER OUTAGES.

15

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
541 PM EDT FRI JUN 23 2006

GAZ058-232215-
541 PM EDT FRI JUN 23 2006

...SIGNIFICANT WEATHER ALERT FOR PEA SIZED HAIL AND 40 MPH WINDS IN
BUTTS COUNTY UNTIL 615 PM EDT...

AT 537 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER FLOVILLA...MOVING NORTHEAST AT 20 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE PEA SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 40 MPH AS IT MOVES
ACROSS BUTTS COUNTY. SOME LOCATIONS IN THE PATH OF THIS STORM
INCLUDE FLOVILLA AND EASTERN BUTTS COUNTY. BRIEF HEAVY DOWNPOURS MAY
CAUSE PONDING OF WATER ON ROADWAYS.