Area Forecast Discussion
Issued by NWS Atlanta, GA
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FXUS62 KFFC 040919
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
520 AM EDT SUN OCT 4 2009
.SHORT TERM /TODAY THROUGH TUESDAY/...
A RATHER COMPLICATED PATTERN SETTING UP FOR THIS AFTERNOON THROUGH
TUESDAY. WEAK HIGH PRESSURE CURRENTLY OVER NORTH GEORGIA WILL SHIFT
TO OUR EAST PUTTING MOST OF THE
CWA IN AN EASTERLY
FLOW. AT THE SAME
TIME...
MOISTURE FROM WHAT IS LEFT OF OLAF...WILL BE MOVING TOWARD
THE
CWA. THIS IS ALREADY PRODUCING WIDESPREAD RAIN AND A FEW
THUNDERSTORMS OVER TX/LA/AR.
GFS IS THE FASTEST IN BRINGING THE
PRECIP INTO WESTERN GA THIS AFTERNOON WHILE THE
NAM/SREF HOLD THE
PRECIP TO OUR WEST UNTIL AFTER 00Z. BASED ON THE CURRENT LOCATION OF
THE PRECIP SHIELD...THE
GFS HAS A BETTER HANDLE ON TIMING AND WILL
STICK CLOSER TO THE
GFS ON
POPS THIS AFTERNOON. TO COMPLICATE
THINGS...THE SURFACE
FRONT THAT MOVED THROUGH US HAS BECOME
STATIONARY ACROSS NORTH FL/SOUTHEAST GA WESTWARD TO SOUTHERN TX. A
SURFACE LOW DEVELOPS ALONG THE
FRONT TODAY AND MOVES ALONG THE
FRONT
THROUGH MONDAY. THIS IS SETTING UP FOR AN
OVERRUNNING EVENT AND IT
APPEARS THE MODELS HAVE PICKED UP ON THIS PUTTING THE HEAVIEST
QPF
OVER NORTH GA. THIS IS ALSO WHERE THE GREATEST
ISENTROPIC LIFT WILL
BE TONIGHT AND MONDAY.
QPF OF 1 TO 3 INCHES ACROSS NORTH GA LOOKS
GOOD WITH LESSER AMOUNTS OVER CENTRAL GA. CENTRAL GA APPEARS TO HAVE
DRIED OUT ENOUGH AND 1 TO 2 INCHES SHOULD NOT CAUSE ANY FLOODING
PROBLEMS...HOWEVER NORTH OF THE
FALL LINE IS WHERE THE PROBLEMS WILL
LIE AND WILL THEREFORE ISSUE A
FLOOD WATCH FOR TONIGHT THROUGH
MONDAY EVENING FOR THE AREAS ALONG AND NORTH OF THE
FALL LINE. THIS
IS ALSO SUPPORTED BY THE GRIDDED
FLASH FLOOD GUIDANCE VALUES. AT THE
ONSET DO NOT EXPECT ANY
THUNDER AS THE
ATMOSPHERE WILL BE RATHER
STABLE...HOWEVER
GFS AND TO SOME EXTENT THE
NAM ARE SHOWING NEGATIVE
SHOWALTER INDEX VALUES ACROSS WESTERN GA AND WILL ADD
ISOLATED
THUNDER AFTER MIDNIGHT. ENOUGH
INSTABILITY MONDAY TO KEEP THE
MENTION OF
THUNDER GOING ALL AREAS.
AS THE SURFACE LOW MOVES TO THE SOUTHEAST MONDAY NIGHT...SOME WEAK
RIDGING DEVELOPS OVER THE AREA MONDAY NIGHT AND TUESDAY AND THIS
WILL DIMINISH THE THREAT OF HEAVY RAIN.
TEMPS WILL BE CLOSE TO
PERSISTENCE TODAY...HOWEVER WITH AN EAST LOW
LEVEL
FLOW...CLOUDS AND RAIN...TEMPS WILL BE MUCH COOLER MONDAY WITH
A SLIGHT WARM UP ON TUESDAY.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST RUN OF THE
GFS IN GOOD AGREEMENT WITH THE 12Z RUN OF THE
ECMWF. ANOTHER AREA OF HEAVY RAIN WILL MOVE INTO THE
CWA WEDNESDAY
AHEAD OF THE COLD
FRONT BUT THIS WILL BE A QUICK SHOT ON WEDNESDAY.
THE SHORT WAVE RESPONSIBLE MOVES QUICKLY INTO NEW ENGLAND AND THEN
OUT INTO THE ATLANTIC. AT THE SAME TIME ANOTHER SHORT WAVE
TROUGH
DROPS OUT OF CANADA AND INTO THE WESTERN US AS THE
H5 HIGH HOLDS
OVER THE EASTERN GULF. THIS WILL KEEP THE
CWA IN A WEST TO SOUTHWEST
FLOW. AS THIS SHORT WAVE LIFTS TOWARD THE END OF THE WEEK ANOTHER
FRONT WILL DROP INTO THE
CWA BRINGING ANOTHER CHANCE OF RAIN WITH
THE BEST CHANCE OVER THE WEEKEND.
&&
.AVIATION...
VFR CONDITIONS EXPECTED TO PREVAIL THROUGH 06Z. INCREASING
MOISTURE
DEEPENS SUFFICIENTLY FOR PRECIPITATION TO BEGIN ACROSS WEST GEORGIA
AFTER 00Z. AS THE LOWER LEVELS SATURATE...
MVFR CEILINGS AND
VISIBILITIES DEVELOP BETWEEN 06Z AND 12Z.
INSTABILITY REMAINS
MARGINAL THROUGH 12Z MONDAY WITH ONLY
ISOLATED THUNDERSTORMS
POSSIBLE. NORTHWEST LOW LEVEL WINDS BECOME EASTERLY ACROSS MOST OF
THE FORECAST AREA BY 18Z.
&&
.PRELIMINARY POINT TEMPS/
POPS...
ATHENS 76 55 60 54 72 / 30 100 80 30 30
ATLANTA 75 55 61 54 72 / 50 100 80 20 40
BLAIRSVILLE 65 52 57 49 69 / 30 100 70 30 40
CARTERSVILLE 73 54 60 54 73 / 50 100 70 20 40
COLUMBUS 79 61 66 63 77 / 50 90 90 20 40
GAINESVILLE 71 55 60 53 70 / 40 100 70 30 30
MACON 78 60 64 61 77 / 30 90 90 20 40
ROME 67 56 62 55 73 / 60 100 70 20 40
PEACHTREE CITY 75 56 62 54 71 / 50 100 90 20 40
VIDALIA 81 61 72 64 81 / 10 60 80 30 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM THIS EVENING THROUGH MONDAY EVENING FOR THE
FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BUTTS...
CARROLL...CATOOSA...CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...
COBB...COWETA...DADE...DAWSON...DEKALB...DOUGLAS...FANNIN...
FAYETTE...FLOYD...FORSYTH...GILMER...GORDON...GREENE...
GWINNETT...HALL...HAN****...HARALSON...HARRIS...HEARD...HENRY...
JACKSON...JASPER...JONES...LAMAR...LUMPKIN...MADISON...
MERIWETHER...MONROE...MORGAN...MURRAY...NEWTON...NORTH FULTON...
OCONEE...OGLETHORPE...PAULDING...PICKENS...PIKE...POLK...
PUTNAM...ROCKDALE...SOUTH FULTON...SPALDING...TALBOT...
TALIAFERRO...TOWNS...TROUP...UNION...UPSON...WALKER...WALTON...
WARREN...WHITE...WHITFIELD...WILKES.
&&
$$
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