825
FXUS62 KFFC 130603 AAA
AFDFFC
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
155 AM EDT TUE AUG 13 2013
.UPDATE...
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS CENTRAL
GA FOR A FEW MORE HOURS. ANOTHER CLUSTER OF STORMS WILL MOVE
ACROSS NORTHERN PORTIONS OF THE STATE FOR THE NEXT FEW HOURS.
UPDATED THE POPS TO REFLECT CURRENT RADAR TRENDS.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
.PREV DISCUSSION... /ISSUED 741 PM EDT MON AUG 12 2013/
UPDATE...
HIGH PRESSURE REMAINS SITUATED ACROSS MUCH OF THE WESTERN CWFA
THIS EVENING...WITH A LEE TROUGH IN THE EAST. MAINLY OUTFLOW
DRIVEN CONVECTION CONTINUES THIS EVENING. THE ATMOS REMAINS
UNSTABLE...BUT ACTIVITY SHOULD BEGIN TO DIMINISH IN STRENGTH AND
COVERAGE WITH THE LOSS OF HEATING. HAVE UPPED POPS ACROSS CENTRAL
GA TO REFLECT CURRENT RADAR TRENDS. HAVE ALSO TWEAKED HOURLY
TEMPS/DEWS.
PREV DISCUSSION... /ISSUED 325 PM EDT MON AUG 12 2013/
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
UPPER HIGH REMAINS IN PLACE OVER THE SOUTHEAST...WHILE AN UPPER LOW
REMAINS OVER SOUTHEAST CANADA. AS THE SHORT TERM PROGRESSES...A
SHORTWAVE ROUNDING THE BASE OF THE LOW WILL DEEPEN THE TROUGH...
FORCING THE UPPER HIGH TO RETROGRADE BACK TOWARD TE SOUTHERN PLAINS.
AS THE UPPER TROUGH DEEPENS...IT WILL PUSH A FRONT AHEAD OF IT INTO
THE SOUTHEAST...MAKING IT INTO CENTRAL GEORGIA BY THE END OF THE
SHORT TERM. SYNOPTIC GUIDANCE IS IN REASONABLE AGREEMENT...THOUGH
THE NAM IS ON THE STRONG SIDE OF SOLUTIONS. GFS AND ECMWF PRETTY
CLOSE WITH THE EXCEPTION OF SOME CONVECTIVE FEEDBACK ON THE GFS.
WITH PW VALUES REMAINING NEAR 2 INCHES AND WITH VERY WEAK WESTERLY
FLOW ALOFT...SCATTERED TO WIDESPREAD CONVECTION WILL CONTINUE THIS
AFTERNOON AND EVENING...FORCED MAINLY BY DIURNAL HEATING AND WEAK
RIPPLES IN THE FLOW ALOFT. SHOULD SEE A DIURNAL LULL TONIGHT BUT AS
THE SURFACE FRONT APPROACHES SHOULD SEE AN INCREASE IN ACTIVITY
TUESDAY MORNING. AS HAS BEEN THE CASE THE PAST SEVERAL DAYS...MAIN
THREAT BOTH WITH TONIGHT AND TOMORROW WILL BE BRIEF HEAVY RAIN AND
OF COURSE OCCASIONAL LIGHTNING. LUCKILY THERE IS ENOUGH FLOW ALOFT
TO KEEP STORMS MOVING...ALBEIT SLOWLY...BUT THERE IS ALWAYS THE
POSSIBILITY THAT A STORM MAY GET STUCK ON TERRAIN. HOWEVER...WITH
THE FRONT IN THE VICINITY ON TUESDAY ISOLATED DAMAGING WIND GUSTS
CANNOT BE RULED OUT.
TOOK A BIAS-CORRECTED BLEND FOR TEMPERATURES WITH ONLY MINOR
ADJUSTMENTS. HIGHS TOMORROW SHOULD BE COOLER THAN TODAY BUT THEN
AGAIN THAT MAY DEPEND ON HOW MUCH IT RAINS THIS AFTERNOON...WHICH
WOULD OF COURSE KEEP TEMPS DOWN. IN ANY CASE...FOR THE MOST PART
THROUGH THE SHORT TERM TEMPS SHOULD BE AT TO JUST SLIGHTLY BELOW
NORMAL...WITH THE BEGINNING OF A COOLING TREND TOWARD THE END OF THE
PERIOD.
AS THE DEEP UPPER TROUGH DIGS TOWARD THE EASTERN SEABOARD...HIGH
PRESSURE WILL BUILD IN BEHIND THE FRONT. THIS IS JUST BARELY HINTED
AT WITH SLOWLY LOWERING DEWPOINTS LATE IN THE PERIOD AND COOLER LOWS
FOR TUESDAY NIGHT...BUT MORE IMPORTANTLY WITH THE CONFLUENT FLOW
ALOFT...ONCE THE APPROACHING HIGH CLEARS THE APPALACHIANS...IT WILL
BEGIN TO RIDGE DOWN THE EASTERN SEABOARD IN A HYBRID CAD SETUP.
AGAIN...THROUGH THE SHORT TERM WE SEE ONLY THE BEGINNING HINTS OF
THIS...BUT WITH SIGNIFICANT IMPACTS INTO THE EXTENDED.
TDP
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
SOME TWEAKS MADE TO POPS TO ACCOUNT FOR BETTER POSSIBILITY OF
CONVECTION CLOSER TO FRONT WEDNESDAY NIGHT THROUGH FRIDAY.
OTHERWISE CURRENT EXTENDED FORECASTS LOOK ON TRACK.
PREV DISCUSSION... /ISSUED 406 AM EDT MON AUG 12 2013/
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
GFS AND ECMWF MODELS ARE IN GENERAL AGREEMENT THROUGH THE
EXTENDED FORECAST PERIOD. A COLD FRONT FROM THE MID ATLANTIC
STATES THROUGH THE TN VALLEY SHOULD GRADUALLY MOVE SOUTH INTO GA
WEDNESDAY THROUGH THURSDAY. THE VERY MOIST TROPICAL AIRMASS OVER
GA...PWS AROUND 2 INCHES...WILL COMBINE WITH A SERIES OF UPPER
LEVEL DISTURBANCES MOVING OVER AND PARALLEL TO THE FRONTAL
BOUNDARY TO PRODUCE SCATTERED TO NUMEROUS THUNDERSTORMS. A BROAD
UPPER LEVEL TROUGH OVER THE GREAT LAKES REGION IS EXPECTED TO
DEEPEN OVER THE MS RIVER VALLEY THURSDAY THROUGH SUNDAY. AS THIS
OCCURS THE SURFACE FRONT SHOULD REMAIN NEARLY STATIONARY OVER
SOUTH GA. THE CLOUDY AND WET PATTERN SHOULD CONTINUE WITH SHOWERS
AND THUNDERSTORMS LIKELY OVER THE STATE THURSDAY THROUGH SUNDAY.
SIGNIFICANT QPF AMOUNTS UP TO 3 INCHES CAN BE EXPECTED OVER
CENTRAL GA DURING THE END OF THE WEEK WITH AROUND 1 INCH OVER
NORTH GA. NEAR SEASONAL TEMPERATURES ON WEDNESDAY WILL LOWER 5 TO
10 DEGREES BELOW NORMAL DURING THE DAY THURSDAY THROUGH SUNDAY DUE
TO CLOUDS AND RAIN.
16
AVIATION...
06Z UPDATE...
EXPECTING MVFR CIGS WITH LOCALIZED IFR CIGS THIS MORNING DUE TO WET
GROUND FROM MONDAYS RAINFALL. LOW CIGS SHOULD IMPROVE TO VFR BY 14Z.
SCATTERED TSTMS SHOULD BEGIN TO DEVELOP AFTER 17Z WHICH MAY AFFECT
THE TAF SITES WITH VARIOUS OUTFLOW BOUNDARIES THAT COULD CAUSE
ERRATIC WIND SHIFTS AND GUSTS. GENERALLY A WESTERLY FLOW OF 5 TO 10
KTS THROUGH THE FORECAST PERIOD.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS.
16
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 71 90 70 86 / 60 60 30 40
ATLANTA 72 87 70 86 / 60 60 30 40
BLAIRSVILLE 68 84 64 81 / 60 60 40 40
CARTERSVILLE 70 87 68 86 / 50 60 40 40
COLUMBUS 74 91 73 90 / 60 50 30 40
GAINESVILLE 71 86 70 84 / 50 60 40 40
MACON 71 91 71 89 / 60 50 30 40
ROME 71 87 68 86 / 50 60 40 40
PEACHTREE CITY 71 87 70 87 / 60 60 30 40
VIDALIA 75 93 73 87 / 30 40 30 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$