FXUS62 KFFC 142222 AAA
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
520 PM EST MON DEC 14 2009
.UPDATE...
DECIDED AT THE LAST MINUTE TO ISSUE A DENSE FOG ADVISORY FOR MOST
OF CENTRAL GEORGIA...GENERALLY WHERE THE WARM FRONT WILL SLOWLY
LIFT NORTHWARD OVERNIGHT. APPROACHING RAINFALL MAY MIX OUT SOME OF
THE FOG...BUT THERE ARE JUST TOO MANY AREAS WITH VSBYS BELOW 1/2
MILE AND THAT SHOULD REMAIN THE NORM FOR THE NIGHT.
&&
SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
MODELS ARE IN GOOD AGREEMENT FOR THE SHORT TERM...ALTHO GFS IS
STILL HAVING CONVECTIVE FEEDBACK ISSUES. DISREGARDING PRECIP
AMOUNTS FROM GFS...BUT LOCATION AND TIMING IS CONSISTENT WITH NAM
AND SREF. ISENTROPIC LIFT IS STRONGEST...ALTHOUGH NOT OVERLY
IMPRESSIVE...THIS AFTERNOON AND THEN WEAKENS AS WINDS VEER TO AN
ORIENTATION MORE PARALLEL TO PRESSURE CONTOURS. THIS PATTERN HOLDS
THROUGH TUESDAY AFTERNOON WHEN A COLD FRONT BEGINS PUSHING THROUGH
THE STATE FROM THE NORTHWEST. THIS BODES FOR AT LEAST TWO ROUNDS
OF LIGHT TO MODERATE DRIZZLE/RAIN ACROSS CENTRAL GA AHEAD OF THE
FRONT AS WEAK IMPULSES RIDE THROUGH THE ZONAL FLOW. CANNOT RULE
OUT A STRAY THUNDERSTORM IN CENTRAL GA OVERNIGHT...BUT NO CHANCES
IN THE NORTH DUE TO TREMENDOUS STABILITY ALOFT PER FFC SOUNDING.
WILL DROP MAX TEMPS ON TUE A FEW DEGREES FROM GUIDANCE PER LOCAL
BIAS ANALYSIS. CONTINUED CLOUD COVER AND WEAKER WARM ADVECTION
SUGGESTS MAX TEMPS WILL NOT RISE AS MUCH AS PROGGED DURING THE DAY.
OVERALL CONFIDENCE IS MODERATE.
LONG TERM /THURSDAY THROUGH MONDAY/...
LONG TERM MODELS COMING INTO SOME SEMBLANCE OF
AGREEMENT FOR THE LOW DEVELOPING IN THE GULF BY WEEK'S END. EARLIER
RUNS WERE RATHER DIVERGENT IN THEIR SOLUTION. ECMWF PULLED BROAD
LOW ACROSS FL PANHANDLE WITH PRECIP SPREADING INTO NORTHERN GA.
UKMET DID THE SAME BUT WITH PRECIP STAYING FARTHER SOUTH. 12Z GFS
NOW AGREES WITH THIS SCENARIO BUT IS MORE LIKE THE UKMET IN KEEPING
NORTHERN EDGE OF PRECIP IN SOUTHERN GA. WILL RAISE POPS SLIGHTLY IN
THE SOUTHERN COUNTIES ON FRIDAY TO REFLECT THIS...AND THEN DROP POPS
FROM SUNDAY AS RIDGE BUILDS BACK IN STRONGLY AFTER LOW TREKS UP THE
EAST COAST.
HYDROLOGY...
RAINFALL FOR THE NEXT 24 HOURS(TONIGHT/TUESDAY)EXPECTED TO STAY IN
THE 1/4 TO 1 INCH RANGE ACROSS NORTHERN GA...BUT BETTER MOISTURE
CONVERGENCE AND UPPER LEVEL IMPULSES OVERNIGHT COULD BRING LOCALIZED
CONVECTION AND UP TO TWO ADDITIONAL INCHES OF RAIN ACROSS CENTRAL
GA. A FLOOD WATCH HAS BEEN ISSUED TO ADDRESS THIS AREA TONIGHT.
DUE TO THE STEADY WEAK/MODERATE RAINFALL EXPECTED...ANY FLOODING
THAT OCCURS WILL LIKELY BE SLOW /THAT IS...NOT FLASH FLOOD/ AND
MINOR.
&&
.AVIATION...
LIFR WILL CONTINUE THROUGH MUCH OF THE NIGHT MOST AREAS. SOME MIXING
WITH THE CONVECTION BUT IT HAS BEEN SHORT LIVED AND THE CIGS/VSBYS
COME BACK DOWN AFTER THE SHOWER/TSTORM. THE WARM FRONT WILL LIFT
NORTH OF THE FORECAST AREA LATE THIS EVENING IN ADVANCE OF THE COLD
FRONT WHICH SHOULD BE MOVING THRU THE ATL AREA BY 12Z AND PAST MACON
BY 21Z. AFTER FROPA...CIGS WILL LIFT SLOWLY. IN FACT THE 925MB
MOISTURE HOLDS A STRATO CU DECK OVER ATL UNTIL AFTER 00Z WED...THEN
THE CAA AND GUSTY WINDS KICK IN. NAM APPEARS TO HAVE A BETTER HANDLE
OF POSITION OF THE PRECIP AND HAVE LEANED IN THAT DIRECTION. FEEL
THE BEST CHANCE OF THUNDER AT ATL/AHN WILL BE EARLY IN THE FORECAST.
AFTERWARDS THE THREAT DIMINISHES HOWEVER THE PRECIP WILL CONTINUE
ALONG WITH FOG/DRIZZLE UNTIL FROPA WITH A FEW LINGERING
SHOWERS/DRIZZLE SHORTLY AFTER FROPA.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 51 58 38 57 30 / 70 40 5 0 0
ATLANTA 55 58 38 58 34 / 80 50 5 0 0
BLAIRSVILLE 44 52 34 53 25 / 40 20 5 0 0
CARTERSVILLE 53 56 33 56 27 / 60 30 0 0 0
COLUMBUS 60 61 42 62 35 / 90 80 20 0 0
GAINESVILLE 50 57 37 56 31 / 60 30 5 0 0
MACON 60 61 42 62 32 / 90 80 20 0 0
ROME 52 56 35 58 25 / 50 30 0 0 0
PEACHTREE CITY 55 61 36 58 24 / 80 50 5 0 0
VIDALIA 59 69 47 60 32 / 70 80 30 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EST TUESDAY FOR THE FOLLOWING
ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY...
BUTTS...CARROLL...CHATTAHOOCHEE...CHEROKEE...CLARKE...CLAYTON...
COBB...COWETA...CRAWFORD...DAWSON...DEKALB...DOOLY...DOUGLAS...
FAYETTE...FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...
GWINNETT...HALL...HANCOCK...HARALSON...HARRIS...HEARD...HENRY...
HOUSTON...JACKSON...JASPER...JEFFERSON...JONES...LAMAR...MACON...
MADISON...MARION...MERIWETHER...MONROE...MORGAN...MUSCOGEE...
NEWTON...NORTH FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH...
PICKENS...PIKE...POLK...PULASKI...PUTNAM...ROCKDALE...SCHLEY...
SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT...
TALIAFERRO...TAYLOR...TROUP...TWIGGS...UPSON...WALTON...WARREN...
WASHINGTON...WEBSTER...WILKES...WILKINSON.
FLOOD WATCH THROUGH TUESDAY EVENING FOR THE FOLLOWING ZONES:
BLECKLEY...CHATTAHOOCHEE...CRISP...DODGE...DOOLY...EMANUEL...
HOUSTON...JOHNSON...LAURENS...MACON...MARION...MONTGOMERY...
MUSCOGEE...PULASKI...SCHLEY...STEWART...SUMTER...TELFAIR...
TOOMBS...TREUTLEN...WEBSTER...WHEELER...WILCOX.
&&
$$
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