Flash Flood in Georgia, May 16, 2009

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1137 AM EDT SAT MAY 16 2009

.UPDATE...
RESENT THE ZONES TO REFRESH THE WORDING FOR THE AFTERNOON...DID NOT
MAKE ANY CHANGES HOWEVER. EXPECT CONVECTION TO BECOME MORE
WIDESPREAD THROUGHOUT THE AFTERNOON HOURS. LATEST RUC ANALYSIS
DEPICTS A VORTICITY MAXIMUM ACROSS EAST CENTRAL ALABAMA. THIS
FEATURE IS ALSO NOTED ON VISIBLE SATELLITE THIS MORNING AS A
SLIGHT SPIN ACROSS EAST CENTRAL ALABAMA. THIS FEATURE IS ACTING AS
A FOCUS FOR CONTINUOUS SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS
WEST CENTRAL GEORGIA THIS MORNING. FRONTAL BOUNDARY IS PARALLELING
THE MISSISSIPPI RIVER AS OF LATE THIS MORNING...WITH ONLY SLOW
PROGRESS TO THE EAST. SOME STRONG THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON...WITH MIXED LAYER CAPE VALUES OF 1500-2000 J/KG. SHEAR
IS ALMOST NONEXISTENT HOWEVER...WITH 0-6KM BULK SHEAR VALUES LESS
THAN 10 KT...SO WHILE MOST STORMS SHOULD REMAIN BELOW SEVERE
LIMITS...A FEW PULSE SEVERE STORMS ARE NOT OUT OF THE QUESTION.
HEAVY RAINFALL APPEARS TO BE A MORE SIGNIFICANT
THREAT...ESPECIALLY ACROSS WEST CENTRAL GEORGIA WHERE CONVECTION
HAS BEEN CONTINUOUS THROUGH THE MORNING HOURS.

&&

.PREV DISCUSSION... /ISSUED 500 AM EDT SAT MAY 16 2009/

SHORT TERM /TODAY THROUGH MONDAY/...
MODELS CONTINUE TO SHOW STRONG COLD FRONT MOVING ACROSS THE
TENNESSEE/LOWER MISSISSIPPI VALLEY REGION TODAY...APPROACHING
EXTREME NORTHWEST GEORGIA EARLY TONIGHT...THEN MOVING TO NEAR AN
ATLANTA TO ATHENS LINE BY 12Z SUNDAY. LOOK FOR CURRENT CONVECTIVE
ACTIVITY AFFECTING PORTIONS OF NORTHWEST GEORGIA EARLY THIS
MORNING TO CONTINUE TO WANE...THEN SHOWERS AND TSTORMS BECOMING
WIDESPREAD OVER MUCH OF THE COUNTY WARNING AREA THIS
AFTERNOON/EVENING IN MOIST INCREASINGLY UNSTABLE AIRMASS OUT AHEAD
OF THE FRONT. STILL NOT OUTLOOKED BY SPC IN RISK OF SEVERE...BUT
THEY DO HAVE MUCH OF NORTH GEORGIA IN THE 5% REGION FOR PROBABILITY
OF SEVERE STORMS DAY ONE. WITH MODEL CAPES IN THE 100O TO 2000 RANGE
OVER MUCH OF NORTH AND WEST GEORGIA THIS AFTERNOON...ISOLATED SEVERE
STORMS NOT OUT OF THE QUESTION. MODELS SIMILAR WITH FRONT PUSHING
INTO CENTRAL GEORGIA SUNDAY AFTERNOON AND LOOK FOR BEST PRECIP
COVERAGE AND THREAT OF SEVERE STORMS TO BE MAINLY OVER CENTRAL AND
SOUTH GEORGIA. AS THE FRONT DRIFTS INTO SOUTH GEORGIA SUNDAY
NIGHT...AND SURFACE HIGH PRESSURE BUILDS SOUTHEAST FROM THE GREAT
LAKES...MODELS SHOW DRIER AIR ADVECTING INTO NORTH GEORGIA...BUT
MAINTAIN SOME DEEPER MOISTURE OVER CENTRAL SECTS WELL INTO MONDAY AS
THE THE FRONT MEANDERS NEAR THE GEORGIA/FLORIDA BORDER.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
EXTENDED PROGS CONTINUE TO OFFER VARYING SOLUTIONS ON THE
EVOLUTION OF A LOW PRESSURE SYSTEM EXPECTED TO DEVELOP OVER THE
SOUTH CENTRAL GULF TUESDAY/WEDNESDAY TIME FRAME. GFS CONTINUE TO
BE THE MOST AGGRESSIVE WITH SPREADING DEEPER MOISTURE ASSOCIATED
WITH THIS FEATURE NORTHWARD INTO OUR AREA. HOWEVER...PLAN TO
CONTINUE PREVIOUS FORECAST TREND WITH SLIGHT CHANCE POPS MAINLY
ACROSS EXTREME SOUTHERN COUNTIES FOR NOW WITH SEVERAL MODEL RUNS
YET TO GO.

AVIATION...UPDATE...
IT LOOKS LIKE A SUCKER HOLE OF MVFR-VFR CEILINGS CAME BY THE ATL
AREA WITH CONDITIONS NOW LESSENING TO THE S AS IFR CEILINGS ARE
FILLING BACK IN OVER THE CCO/FFC AREAS. POTENTIAL FOR IFR-MVFR
CEILINGS THROUGH THE MORNING THAT SHOULD IMPROVE LATER MORNING.
CONVECTIVE SHOWERS HAVE POPPED UP AROUND THE AREA AND WILL TEND TO
KEEP THINGS MIXED UP. EXPECT A FLARE UP OF THUNDERSTORMS TODAY
ACROSS THE AREA...MAXIMIZING DURING THE AFTERNOON AND EVENING.
SURFACE WINDS LIGHT SSE BECOMING SW DURING THE DAY. BDL

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          77  63  74  50  72 /  80  70  60  20  10
ATLANTA         77  62  71  52  71 /  90  70  60  20   5
BLAIRSVILLE     74  60  68  45  67 /  90  80  60  10   5
CARTERSVILLE    78  60  71  50  72 / 100  80  50  10   5
COLUMBUS        81  66  77  56  73 /  70  60  60  30  10
GAINESVILLE     75  61  70  51  70 /  90  80  60  20   5
MACON           83  67  81  53  73 /  60  60  70  40  20
ROME            80  61  71  48  74 /  90  80  50  10   5
PEACHTREE CITY  78  62  74  50  71 /  80  70  60  20   5
VIDALIA         86  66  82  52  70 /  50  50  70  60  40

&&

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

22

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1130 AM EDT SAT MAY 16 2009

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-170900-
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-
1130 AM EDT SAT MAY 16 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

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

.SYNOPSIS...
A COLD FRONT WILL MOVE TO NORTH GEORGIA THIS EVENING AND TO CENTRAL
GEORGIA SUNDAY MORNING.

.PRIMARY HAZARDS...
THE PRIMARY HAZARD FROM THUNDERSTORMS WILL BE GUSTY WINDS...HAIL
AND LIGHTNING. HEAVY RAIN WILL ALSO BE POSSIBLE. THE MOST LIKELY
LOCATION FOR SEVERE THUNDERSTORMS WILL BE NORTH OF ATLANTA AND
ATHENS...THIS AFTERNOON AND EVENING. HOWEVER...SCATTERED TO NUMEROUS
THUNDERSTORMS MAY CONTINUE WELL INTO SATURDAY NIGHT.

.DISCUSSION...
A MOIST AIRMASS WILL CONTINUE OVER THE AREA TODAY. THE AIRMASS WILL
BECOME INCREASINGLY UNSTABLE THIS AFTERNOON WITH CAPES OF 1500 TO
2000 AND LIFT INDICES OF MINUS 4 TO MINUS 7. THIS WILL ALLOW A FEW
STORMS TO BECOME SEVERE AS A COLD FRONT APPROACHES THE AREA. AN
INHIBITING FACTOR FOR SEVERE THUNDERSTORM DEVELOPMENT WILL BE THE
LACK OF VERTICAL WIND SHEAR.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
THERE IS A CHANCE OF THUNDERSTORMS ACROSS THE AREA ON SUNDAY. THERE
IS A CHANCE OF THUNDERSTORMS OVER PARTS OF CENTRAL GEORGIA ON
MONDAY...AND AGAIN ON WEDNESDAY THROUGH FRIDAY.

.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
1103 AM EDT SAT MAY 16 2009

GAZ052-161630-
1103 AM EDT SAT MAY 16 2009

...SIGNIFICANT WEATHER ALERT FOR HEAVY RAIN IN HEARD COUNTY UNTIL
1230 PM EDT...

AT 1102 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
CLUSTER OF SHOWERS AND THUNDERSTORMS OVER MOST OF HEARD COUNTY. THE
LEADING EDGE OF THE STRONGER STORMS EXTENDED FROM NEAR ROOSTERVILLE
TO NEAR TEXAS...AND MOVING EAST NORTHEAST AT 10 MPH. THE SLOW
MOVEMENT OF THESE STORMS AND CONTINUED REDEVELOPMENT OVER THIS SAME
AREA WILL RESULT IN 1 TO 3 INCHES OF RAINFALL FOR MUCH OF HEARD
COUNTY OVER THE NEXT COUPLE OF HOURS.

RUNOFF FROM THESE STORMS WILL CAUSE MINOR FLOODING OF SMALL CREEKS
AND STREAMS...URBAN AREAS...AND LOW LYING FLOOD PRONE AREAS ALONG
HIGHWAYS...STREETS AND UNDERPASSES. SOME AREAS THAT COULD EXPERIENCE
MINOR FLOODING ARE TEXAS...FROLONA... ROOSTERVILLE... EPHESUS...
FRANKLIN AND CENTRALHATCHEE.

DRIVERS SHOULD USE CAUTION AS INTENSE RAINFALL WILL REDUCE
VISIBILITIES. PONDING OF WATER ON ROADWAYS IS LIKELY. DO NOT ATTEMPT
TO DRIVE ACROSS WATER COVERED ROADWAYS.