Special Weather Statement, NWS Atlanta, GA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
150 PM EDT SAT JUL 2 2011

.UPDATE...

MADE SOME MINOR TWEAKS TO HOURLY TEMP GRIDS JUST TO UPDATE BASED
ON OBSERVATIONS...OTHERWISE FORECAST LOOKS GOOD. HI-RES MODELS
STILL SHOWING CONVECTION DEVELOPING AROUND 19-20Z...MOST MODELS
DEVELOPING IT INITIALLY IN THE MOUNTAINS AND SPREADING SOUTH.
CURRENT POP/WX GRIDS COVER THIS WELL BUT WILL MONITOR IN CASE AN
UPDATE IS NEEDED LATER IN THE DAY.

TDP

&&

.PREV DISCUSSION... /ISSUED 737 AM EDT SAT JUL 2 2011/

SHORT TERM /TODAY THROUGH MONDAY/...
/ISSUED AT 305 AM EDT SAT JUL 2 2011/
LARGE-SCALE PATTERN HAS CHANGED ONLY SLIGHTLY IN THE PAST 48
HOURS...WITH FULL WAVE SYSTEM ENTRENCHED OVER THE EASTERN HALF OF
THE COUNTRY.  THE RESULTING NORTHERLY FLOW DOWN THE EAST COAST SENT
WEAK UPPER-LEVEL IMPULSES INTO GEORGIA AROUND MAX HEATING TIME THE
PAST FEW DAYS WHICH HELPED FUEL AFTERNOON CONVECTION.  UPPER
PATTERN...HOWEVER...IS CHANGING AS AXIS OF 500 MB RIDGE
FLATTENS/ROTATES MORE ZONALLY ACROSS THE SOUTH AND ATLANTIC TROF
LIFTS.  THIS HAS BEEN PROGGED WELL FOR PAST SEVERAL RUNS AND ALL
MODELS ARE CONSISTENT WITH THIS CHANGE.  THIS OSTENSIBLY REMOVES
UPPER-LEVEL FORCING FROM THE PICTURE...ALTHOUGH I CANNOT RULE OUT
ONE LAST SHOT OF ENERGY MAKING IT INTO THE STATE TODAY BEFORE THE
RIDGE FLATTENS ACROSS GEORGIA ON SUNDAY.  WATER VAPOR IMAGERY
SUGGESTS A WEAK WAVE SLIDING DOWN THE MID-APPALACHIANS THIS
MORNING...BUT IT IS NOT AS EVIDENT AS IMPULSES THE PAST FEW DAYS.

DESPITE THE CHANGES ALOFT...SURFACE FEATURES WILL CHANGE ONLY
SLIGHTLY...WHICH SPELLS A CONTINUATION OF DIURNAL CONVECTION.  A
WEAK SFC TROF AND MOISTURE GRADIENT PERSISTS ACROSS NORTH-CENTRAL
GEORGIA THIS MORNING AND WILL CONTINUE TO BE A FOCUS ZONE FOR
ACTIVITY THROUGH MID-WEEK /SEE BELOW/.  THE MODELS APPEAR TO OFFSET
THE REDUCTION OF UPPER-LEVEL FORCING WITH ENHANCED SFC CONVERGENCE
ALONG THIS BOUNDARY...SO WILL KEEP AFTERNOON 20-40 POPS IN THE
PICTURE FOR THE NEXT SEVERAL DAYS USING MET GUIDANCE AS THE BASIS.

THE ABSENCE OF FORECAST MID-LEVEL WARMING ASSOCIATED WITH THE
SHIFTING 500 MB RIDGE IS A BIT CURIOUS BUT...IF IT
VERIFIES...SUPPORTS THE CONTINUATION OF AFTERNOON CONVECTIVE
ACTIVITY. IF WARMING IS STRONGER THAN FORECAST...CAPPING MAY BE AN
ISSUE TODAY AND MORE LIKELY SUNDAY.  NMM WRF AND OTHER SHORT-RANGE
MODELS...ON THE OTHER HAND...ALL POINT TO LATE AFTERNOON CONVECTION
TODAY ALONG AN AXIS FROM CSG TO THE NE CORNER OF GA...SO WILL SET
ASIDE MY CONCERN FOR MID-LEVEL WARMING TODAY.  NEED TO WATCH THIS
FOR SUNDAY...THOUGH.

MOS TEMPERATURES HAVE BEEN DOING WELL RECENTLY...ALTHOUGH A TAD WARM
FOR MAX TEMPS...SO WILL STICK PRETTY CLOSE TO THEM.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
/ISSUED AT 305 AM EDT SAT JUL 2 2011/
THE SURFACE BOUNDARY WILL BE THE KEY FORCING FEATURE THROUGH THE
WEEK.  THE STRONG SHORT-WAVE CUTTING ACROSS THE UPPER MIDWEST THIS
MORNING WILL EVENTUALLY WEAKEN AND DIG SOUTHEASTWARD TO REINFORCE
THE SURFACE BOUNDARY ALONG THE APPALACHIANS EARLY IN THE WEEK.  AS
MENTIONED ABOVE...THE UPPER-LEVEL FORCING WILL BE WEAKEST
SUNDAY...BUT ALL MODELS ERODE THE EASTERN LOBE OF THE RIDGE WHICH
WILL GIVE WAY TO STRONGER NORTHEASTERLY FLOW AND A RETURN OF FORCING
ALOFT STARTING MONDAY.  THIS PATTERN HOLDS FOR THE WEEK WHICH BODES
QUITE WELL FOR CONTINUED DIURNAL CONVECTION THROUGH FRIDAY.
TEMPERATURES WILL REMAIN NEAR NORMAL WITH NO ADJUSTMENTS TO GUIDANCE
NEEDED.

27

AVIATION...
18Z UPDATE...
WEAK BOUNDARY ACROSS CENTRAL GA IS HARD TO FIND BUT SHOULD STILL
FAVOR MORE THUNDERSTORMS SOUTH OF CSG TO MCN WITH ONLY ISOLATED
NORTH. HAVE SHOWN ONLY CB OR VCTS FOR NOW AND WILL WATCH TO SEE HOW
CONVECTION DEVELOPS. SCT CUMULUS THIS AFTERNOON 4 TO 5THSD FT
BECOMING MOSTLY CLEAR AFTER 00Z. VISIBILITY LOCALLY 5SM IN HAZE 09Z
TO 13Z. WINDS 5KT OR LESS THIS AFTERNOON GENERALLY E TO SE. WINDS
NEAR CALM OVERNIGHT.

//ATL CONFIDENCE...12Z UPDATE...
MEDIUM ON WIND DIRECTION.
MEDIUM TO HIGH ON TSTM LOCATIONS.
HIGH ON VFR CONDITIONS.

41

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          96  70  95  69 /  20  20  40  30
ATLANTA         94  74  93  73 /  30  20  40  30
BLAIRSVILLE     88  66  89  67 /  20  20  30  20
CARTERSVILLE    96  67  96  69 /  20  10  30  30
COLUMBUS        95  73  94  72 /  40  30  40  30
GAINESVILLE     94  72  93  71 /  20  20  30  30
MACON           96  70  95  68 /  20  30  40  20
ROME            95  67  95  69 /  10  10  20  30
PEACHTREE CITY  95  68  93  68 /  30  30  40  30
VIDALIA         95  70  94  70 /   5   5  20  10

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
214 AM EDT SAT JUL 2 2011

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-031200-
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-
214 AM EDT SAT JUL 2 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...TODAY AND TONIGHT
ISOLATED THUNDERSTORMS EXPECTED THIS AFTERNOON AND EVENING ACROSS
NORTH AND CENTRAL GEORGIA.

.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL INTERACT WITH A WEAK SURFACE
TROUGH STALLED ACROSS PARTS OF NORTH AND CENTRAL GEORGIA TO
PRODUCE ISOLATED THUNDERSTORMS THIS AFTERNOON AND EVENING.

.PRIMARY HAZARDS...
THE PRIMARY HAZARDS FROM ISOLATED THUNDERSTORMS WILL BE FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 50 MPH.

.DISCUSSION...
A WEAK SURFACE TROUGH OF LOW PRESSURE MEANDERING ACROSS PARTS OF
NORTH AND CENTRAL GEORGIA WILL SERVE AS A FOCUS FOR ISOLATED THUNDERSTORMS
THIS AFTERNOON AND EVENING. MODEST INSTABILITIES AND WEAK WIND SHEAR
PROFILES SHOULD HELP HOLD MOST THUNDERSTORM DEVELOPMENT BELOW
SEVERE LIMITS. HOWEVER... AN ISOLATED PULSE SEVERE STORM CANNOT BE
RULED OUT AS AN UPPER LEVEL DISTURBANCE IS EXPECTED TO TRAVERSE
THE STATE DURING MAX HEATING. OTHERWISE... THE THUNDERSTORM THREAT
WILL GREATLY DIMINISH BEFORE MIDNIGHT WITH LOSS OF DAYTIME HEATING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY
ISOLATED TO SCATTERED THUNDERSTORMS EXPECTED EACH AFTERNOON AND
EVENING.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
308 PM EDT SAT JUL 2 2011

GAZ061-073-074-084-021945-
308 PM EDT SAT JUL 2 2011

...SIGNIFICANT WEATHER ADVISORY FOR 40 MPH WINDS IN WASHINGTON...
WILKINSON...BALDWIN AND HANCOCK COUNTIES UNTIL 345 PM EDT...

AT 306 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORMS NEAR LINTON AND DEEPSTEP...MOVING WEST AT 15
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...WILKINSON...BALDWIN AND HANCOCK COUNTIES THROUGH
345 PM EDT. SOME LOCATIONS IN THE PATH OF THESE STORMS INCLUDE
WARTHEN...DEEPSTEP...LINTON...HEBRON...DEVEREUX...BEULAH AND
UNDERWOOD. BRIEF HEAVY DOWNPOURS WILL CAUSE PONDING OF WATER ON
ROADWAYS.

&&

LAT...LON 3288 8316 3325 8324 3325 8282 3301 8276
TIME...MOT...LOC 1907Z 083DEG 13KT 3315 8292