Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 301129
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
729 AM EDT SAT MAY 30 2015



.PREV DISCUSSION... /ISSUED 349 AM EDT SAT MAY 30 2015/

SHORT TERM /TODAY THROUGH SUNDAY/...
MODELS ARE MOSTLY IN AGREEMENT THROUGH THE SHORT TERM. ATLANTIC
MOISTURE WILL CONTINUE TO SPREAD INTO SOUTH/CENTRAL GEORGIA THIS
MORNING AS SEEN WITH SHOWERS JUST OFF SHORE MOVING WESTWARD. A FEW
OF THESE COULD MAKE IT INTO THE EXTREME SOUTHEAST/EASTERN PARTS OF
THE CWA LATER THIS MORNING AND AFTERNOON. WITH DAYTIME HEATING A
FEW STORMS COULD DEVELOP ACROSS NORTHWEST/NORTH GA THIS AFTERNOON.
THE REST OF THE CWA SHOULD BE DRY TODAY. MODELS BRING A SHORT WAVE
INTO THE CWA LATE TONIGHT AND SUNDAY. THIS WILL INCREASE
POPS...MAINLY AFTER MIDNIGHT AND INTO SUNDAY. THE BEST LOCATION
WILL BE ACROSS NORTH GEORGIA. CAPE VALUES INCREASE TO OVER 2600
AND LAPSE RATES INCREASE TO OVER 8 DEGREES. THIS WILL BE ENOUGH
FOR SOME STORMS TO BE STRONG ALONG WITH ISOLATED SEVERE POSSIBLE
SUNDAY AFTERNOON...MAINLY ACROSS NORTH GEORGIA.

17

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
SYNOPSIS...00Z GFS AND ECMWF BEGIN THE PERIOD IN GOOD AGREEMENT
BUT ONCE AGAIN DIVERGE ON THE EVOLUTION OF A CUTOFF LOW OVER THE
GOM/GULF COAST STATES BY MID WEEK. DIFFERENCES IN THE POSITION OF
THE CUTOFF LOW MAKE THE FORECAST CONFIDENCE FAIRLY LOW FOR DAYS 5
THROUGH 7 ESPECIALLY. GOOD NEWS IS BOTH MODELS ARE CONSISTENT IN
DEVELOPING MUCH NEEDED RIDGING OVER TEXAS AND THE CENTRAL U.S.
WHERE AN ARK IS THE PREFERRED TRANSPORTATION METHOD CURRENTLY.

INTERESTING TO NOTE WITH THE CURRENT MCS OVER TEXAS ATTM AND THE
ASSOCIATED VORT MAX ARE WHAT ULTIMATELY LEAD TO THE EVENTUAL CUT
OFF LOW AND OUR POTENTIAL WEEK LONG WEATHER MAKER. HOWEVER...THE
GFS IS CURRENTLY DOING A BIT BETTER WITH THE POSITION AND TRACK OF
THAT SYSTEM WHICH LENDS ITSELF TO A POTENTIAL BETTER SOLUTION
DOWNSTREAM WITH THE CUT OFF LOW. TOO EARLY TO TELL AT THIS POINT
BUT CERTAINLY SOMETHING TO WATCH.

SUNDAY NIGHT THROUGH TUESDAY...FAIRLY DECENT COVERAGE OF STORMS
EXPECTED SUNDAY NIGHT TO START THE PERIOD AS A WEAK SHORTWAVE AND
SURFACE FRONT MOVE INTO THE REGION. BY MONDAY THE MEAN 500MB TROF
AXIS IS CENTERED OVER US WITH A WEAK SURFACE FRONT LOCATED ACROSS
CENTRAL GA PROVIDING A FOCUS FOR AFTERNOON STORMS. WITH THE LACK OF ANY
REAL SUPPRESSION...AFTERNOON STORMS WILL BE PREVALENT EACH DAY. AT
THE SAME TIME PER THE GFS AND GFS ENSEMBLE...CUT OFF LOW TAKING
SHAPE ANYWHERE FROM CENTRAL GULF OF MEXICO TO SOUTH MISSISSIPPI TO
FL PANHANDLE. ECMWF HAS TRENDED A TAD WEST FROM PREVIOUS RUNS BUT
IS STILL ON THE EASTERN EDGE OF THE MODEL SUITE.

WEDNESDAY THROUGH FRIDAY...THE CUTOFF LOW...WHERE EVER IT ENDS
UP...BEGINS TO TAP INTO SIGNIFICANT AMOUNTS OF DEEP TROPICAL
MOISTURE FROM THE NORTHWEST CARRIBEAN. REGARDLESS OF WHETHER YOU
GO WITH THE ECMWF OR GFS...THEY BOTH AGREE ON THE DEEP MOISTURE
TAP BY THE LOW AND BEGIN TO BRING THAT MOISTURE NORTH ON THE EAST
SIDE OF THE LOW...WHICH IS WHY IT WILL BE IMPORTANT TO KNOW WHERE
THE LOW EVENTUALLY ENDS UP. A WESTERN POSITION WILL MEAN HIGHER
POPS...MORE RAIN...AND INCREASED FLOOD POTENTIAL FOR US WEDNESDAY
THRU FRIDAY WHILE A FURTHER EAST LOCATION WILL STILL MEAN A CHANCE
OF RAIN...BUT MUCH LOWER OVERALL CHANCES AND MINIMAL FLOOD THREAT.
JURY IS STILL OUT ON THE EVENTUAL EVOLUTION OF THE LOW...BUT AM
STILL LEANING TOWARD A MORE WESTERN POSITION GIVEN THE GFS
ENSEMBLES STILL FAVORING THAT SOLUTION...WHILE NOT AS FAR WEST AS
RUNS 24 HOURS AGO. STILL MAINTAINING AFTERNOON POPS IN THE
FORECAST BUT ONE CAN EXPECT THESE TO CHANGE WITH TIME AS WE
RESOLVE THE UPPER LOW FEATURE. AT THE SURFACE...ALL MODELS
INCLUDING MANY ENSEMBLE MEMBERS ALSO HINTING AT A WEAK LOW WITHIN
THE DEEP TROPICAL PLUME THAT SURGES NORTH. AGAIN...UPPER LOW
POSITION WILL DETERMINE THE FATE OF SUCH A FEATURE IF IT OCCURS AT
ALL. GIVEN THE UPPER LOW AND ITS INFLUENCE...ANY SUCH FEATURE
WOULD BE SOME SORT OF HYBRID TROPICAL SYSTEM LIKELY TO REMAIN
WEAK. AGAIN...STAY TUNED TO THE FORECAST NEXT WEEK AS ITS LIKELY
TO CHANGE AND EVOLVE WITH TIME.

KS


&&

.AVIATION...
12Z UPDATE...
VFR CONDITIONS THROUGH MOST OF TONIGHT. EXPECT MVFR CIGS TO
DEVELOP AROUND 09Z SUN AND REMAIN MVFR THROUGH SUNDAY MORNING.
IT SHOULD REMAIN DRY TODAY ALTHOUGH ISOLATED TSTORMS COULD DEVELOP NORTH
AND WEST OF ATL THIS AFTERNOON. A STORM SYSTEM WILL BRING
INCREASING CHANCES OF CONVECTION SUNDAY MORNING AND HAVE ADDED
PROB30 TSRA TO ATL 17Z SUN. WINDS WILL BE SOUTHEAST THROUGH
TONIGHT...THEN BECOME SOUTHWEST AFTER SUNRISE SUNDAY MORNING.

//ATL CONFIDENCE...12Z UPDATE...
MEDIUM ON CIGS LATE TONIGHT AND SUNDAY.
MEDIUM ON TIMING OF CONVECTION SUNDAY.
HIGH ON REMAINING ELEMENTS.


17

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          88  66  86  67 /  20  20  40  50
ATLANTA         86  69  84  67 /  20  30  50  50
BLAIRSVILLE     82  62  78  62 /  20  40  60  60
CARTERSVILLE    86  66  85  65 /  20  40  60  60
COLUMBUS        89  68  89  69 /  10  20  30  30
GAINESVILLE     85  66  83  66 /  20  20  50  50
MACON           90  66  89  68 /  20  20  30  30
ROME            87  66  84  65 /  20  40  60  60
PEACHTREE CITY  87  65  84  65 /  20  30  40  40
VIDALIA         89  69  87  69 /  30  20  30  30

&&

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

$$

SHORT TERM...17
LONG TERM....30
AVIATION...17



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