Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 291743 AAC
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
143 PM EDT FRI MAY 29 2015


.PREV DISCUSSION...

UPDATE...
/ISSUED 1048 AM EDT FRI MAY 29 2015/
HAVE MADE SOME MINOR UPDATES TO THE GRIDS THIS MORNING. BASED ON
CURRENT RADAR TRENDS AND HI RES MODELS...CUT BACK ON POPS
INITIALLY THIS MORNING ACROSS THE CWA AND INTO THE EARLY
AFTERNOON AND THEN AGAIN LATER THIS EVENING. OVERALL VERY LITTLE
CHANGE TO 12 HOUR POP VALUES THOUGH.

OTHER CHANGES WERE BASICALLY JUST TO ACCOUNT FOR HOURLY TRENDS.

11


SHORT TERM /TODAY THROUGH SATURDAY/...
AXIS OF DEEPER MOISTURE REMAINS IN THE VICINITY OF WESTERN AND
NORTHERN GA TODAY. MODELS CONSISTENT IN BUILDING THE UPPER RIDGE
WESTWARD INTO THE FORECAST AREA THIS AFTERNOON INTO SATURDAY.
WITH DRIER AND SOMEWHAT MORE STABLE AIR INDICATED ACROSS PORTIONS
OF EASTERN GA...HAVE CONFINED POPS TO THE NORTH AND WEST TODAY AND
AGAIN SATURDAY. AFTER LOSS OF HEATING...MUCH OF THE FORECAST
AREA SHOULD BE DRY OVERNIGHT. SOME MOISTURE MOVING ON SHORE SATURDAY
AFTERNOON MAY BE SEA BREEZE INFLUENCED...SO HAVE INCLUDED LOW POPS
FOR THE EXTREME EAST CENTRAL AREAS.

GUIDANCE TEMPERATURES LOOK REASONABLE AND HAVE STAYED CLOSE.

41

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
SYNOPSIS...00Z GFS AND ECMWF IN GENERAL PATTERN AGREEMENT AT THE
BEGINNING OF THE EXTENDED THROUGH MIDDAY MONDAY BEFORE DIFFERENCES
IN THE EVOLUTION OF A CUT OFF LOW OVER THE SOUTHERN MISSISSIPPI
VALLEY APPEAR.

SATURDAY AND SUNDAY...MEAN TROF THAT HAS BEEN ANCHORED OVER THE
WESTERN US FOR THE LAST MONTH IT SEEMS BEGINS SHIFTING EAST INTO
THE CENTRAL US WITH RIDGING BUILDING ACROSS THE WEST. GA WILL
REMAIN UNDER THE INFLUENCE OF UPPER RIDGING CENTERED OFF THE EAST
COAST PARTICULARLY SATURDAY AND WANING BY LATE SUNDAY AS THE TROF SHIFTS
EASTWARD ALONG WITH A WEAK SURFACE FRONT. BEST CHANCES FOR RAIN ON
THE WEEKEND WILL REMAIN GENERALLY CONFINED TO FAR NW GA SAT AND
NORTH AND WEST OF I85 ON SUNDAY AFTERNOON AND EVENING. LOOK FOR
TYPICAL AFTERNOON THUNDERSTORMS TO DEVELOP ACROSS THE
AFOREMENTIONED REGIONS EACH DAY.

MONDAY THRU THURSDAY...DIFFERENCES BEGIN TO APPEAR ON MONDAY
BETWEEN THE GFS AND ECMWF OVER THE EVOLUTION OF A CUTOFF LOW AS
ENERGY RIDES OVER THE DEVELOPING WESTERN RIDGE INTO THE BASE OF
THE FAIRLY SHALLOW TROF CENTERED OVER THE MS RIVER AT THAT TIME.
OPERATIONAL GFS WANTS TO CUT THE LOW OFF OVER LA WHICH PUTS OUR
REGION ON THE MOIST FLOW SIDE WITH A TAP INTO A MOISTURE PLUME
FROM THE CARIBBEAN BY WED AND MAKING FOR A MUCH WETTER WEEK. THE
ECMWF ON THE OTHER HAND DELAYS THE ONSET OF CUTTING THE LOW OFF
UNTIL THE MEAN TROF GETS TO AROUND THE 85TH PARALLEL AND THUS
CENTERING THE LOW OVER FLORIDA. THIS DIFFERENCE PUTS OUR AREA ON
THE DRIER NORTH SIDE OF THE LOW MID TO LATE WEEK. GFS ENSEMBLE
RESEMBLES THE OPERATIONAL GFS QUITE A BIT MORE THUS MAKING THE
ECMWF AN OUTLIER FOR NOW. CARRYING ABOVE CLIMO POPS EACH DAY FOR
NOW THAT WILL LIKELY NEED TO BE FINE TUNED EACH DAY FOR NUANCES AS
CONFIDENCE INCREASES. LOCALIZED FLOOD THREAT WILL CERTAINLY BE ON
THE TABLE EACH DAY AS PW VALUES...PER THE GFS...EACH DAY THRU
THURSDAY RANGE FROM 1.50 TO 1.75 INCHES ACROSS THE REGION WHICH
STATISTICALLY IS IN THE 90TH PERCENTILE. STAY TUNED TO THE
FORECAST FOR NEXT WEEK.

KS

&&

.AVIATION...
18Z UPDATE...
SOME SHOWERS/CONVECTION HAVE DEVELOPED ACROSS NORTH GEORGIA AND
THESE WILL PERSIST THROUGH THE AFTERNOON. THERES A SMALL CHANCE
THESE SHOWERS COULD DEVELOP AROUND THE ATL AREA TAF SITES BUT THE
BETTER CHANCES ARE ACTIVITY WILL REMAIN NORTH...AT LEAST OF
ATL. MAIN UNCERTAINTY WITH THE TAF IS POTENTIAL FOR LOW STRATUS
TOMORROW MORNING AT SITES. HAVE INCLUDED FEW-SCT005 TO HINT AT
THIS.

//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE ON WIND AND VSBY. HIGH CONFIDENCE ON CIGS THROUGH
08Z AND THEN LOW CONFIDENCE.

11

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          85  65  86  67 /  20  10  20  20
ATLANTA         83  67  84  69 /  30  10  20  10
BLAIRSVILLE     78  60  79  62 /  40  30  20  20
CARTERSVILLE    84  64  85  66 /  40  20  20  20
COLUMBUS        88  67  88  70 /  20  10  10  10
GAINESVILLE     82  65  83  66 /  30  20  20  20
MACON           87  64  88  68 /  10   5  10  10
ROME            84  64  86  66 /  40  20  30  20
PEACHTREE CITY  85  63  86  65 /  20  10  10  10
VIDALIA         88  68  87  69 /  10   5  30  10

&&

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

$$

SHORT TERM...11
LONG TERM....20
AVIATION...11


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