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000
FXUS62 KFFC 220540
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
135 AM EDT WED MAY 22 2013


.UPDATE...
UPDATED TO INCLUDE SOME POPS THROUGH MIDNIGHT FOR WEST CENTRAL GA AS
WESTWARD MOVING OUTFLOW BOUNDARY LIKELY TO SPAWN A FEW MORE
THUNDERSTORMS. WATCHING CLOSELY STORMS ACROSS NORTH GA FOR
POSSIBLE LOCALIZED FF THREAT AS WELL. MOST STORMS HAVE BEEN
PRODUCING PEA TO NICKEL SIZED HAIL THIS EVE AND EXPECT TREND TO
CONTINUE THROUGH 4Z TO 5Z.

OTHER UPDATE WAS TO GRIDS WED AFTN AND EVE TO INCLUDE SMALL HAIL
AND GUSTY WINDS AS THERE APPEARS TO BE A MARGINAL SEVERE THREAT
DUE TO SLIGHTLY INCREASING DEEP LAYER SHEAR
PROFILES....PARTICULARLY ACROSS NW AND NE GA. WILL NEED TO MONITOR
FOR POTENTIALLY INCREASING SEVERE THREAT AFTER 3 PM WED.

&&


.PREV DISCUSSION... /ISSUED 805 PM EDT TUE MAY 21 2013/

PREV DISCUSSION... /ISSUED 314 PM EDT TUE MAY 21 2013/

SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
MODELS CONTINUE IN GOOD AGREEMENT THROUGH THE SHORT TERM. AIRMASS
SHOWERS/TSTORMS DEVELOPING ACROSS THE CWA...MAINLY ACROSS THE
EXTREME NORTH AND EASTERN PARTS OF THE CWA. THESE WILL DISSIPATE
SHORTLY AFTER SUNSET THIS EVENING. THERE IS A POSSIBILITY THAT THE
STORMS OVER NORTHWEST AL AND CENTRAL TN COULD MAKE IT TO EXTREME
NORTHWEST GA BEFORE DIMINISHING THIS EVENING. THE H5 RIDGE OVER THE
EASTERN U.S. WILL WEAKEN AS THE CENTRAL U.S. TROUGH MOVES INTO THE
MISSISSIPPI VALLEY. THIS WILL PUSH A COLD FRONT INTO THE TENNESSEE
VALLEY WEDNESDAY WHICH WILL BRING A BETTER CHANCE OF THUNDERSTORMS
TO THE CWA...MAINLY ACROSS NORTH GA. INSTABILITY INCREASES WEDNESDAY
ACROSS NORTH GA AND THIS COULD PRODUCE A FEW STRONG STORMS. GUIDANCE
TEMPS LOOK GOOD FOR TONIGHT...ALTHOUGH TRICKY FOR WEDNESDAY WITH
ADDITIONAL CLOUDS. WILL TREND TO THE COOLER SIDE OF GUIDANCE ACROSS
NORTH GA FOR HIGHS ON WEDNESDAY DUE TO INCREASED CLOUDS AND PRECIP.

17

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
BY WEDNESDAY EVENING...BOTH THE GFS AND ECMWF INDICATE THAT THE
FRONT WILL BE WEAKENING SIGNIFICANTLY. GFS REMAINS AB IT ON THE
STRONG SIDE WITH A SLIGHTLY MORE EAST WITH THE GREAT LAKES SURFACE
LOW. BOTH ARE TRANSITIONING THE UPPER LOW TO MORE OF A SHARP OPEN
TROUGH PHASING WITH THE LONGWAVE TROUGH IN CANADA. WEAK SHORTWAVE
OFF THE SOUTH CAROLINA COAST WILL LIFT NORTHEAST AND BE ABSORBED
BY THE LONGWAVE TROUGH AS WELL. SPC CONTINUES THE AREA IN GENERAL
THUNDER FOR THURSDAY...WITH MUCAPE VALUES 500-1000 J/KG EARLY IN
THE DAY...DECREASING BY MID-MORNING...AND INCREASING AGAIN IN
EXTREME SOUTHERN ZONES JUST AHEAD OF THE FRONT AFTER 18Z TO OVER
1000 J/KG. WILL HAVE TO MONITOR THE AREA FOR THE POTENTIAL FOR
ISOLATED STRONG STORMS BUT NOTHING TO SIGNIFICANT.

COLD FRONT SHOULD BE PUSHED THROUGH THE AREA BY LATE THURSDAY...
AND HAVE DECREASED TEMPS NORTHWEST SOMEWHAT TO LINE UP WITH THAT
TIMING A LITTLE BETTER. SHOULD SEE A SIGNIFICANT DECREASE IN TEMPS
TOWARD THE END OF THE WEEK WITH SURFACE HIGH PRESSURE BUILDING IN
AND NORTHWEST FLOW ALOFT...CURRENT FORECAST HAS HIGHS ON FRIDAY
ABOUT 5 DEGREES COOLER THAN HIGHS ON THURSDAY EXCEPT IN CENTRAL
GEORGIA. SEE PREVIOUS LONG TERM DISCUSSION BELOW.

TDP

AVIATION...
06Z UPDATE...
SOME MID/HIGH CLOUDS LINGERING INTO THE MORNING HOURS. VISIBILITY
SHOULD REMAIN ABOVE 6SM...BUT MAY DROP TO MVFR MAINLY ATHENS AND
MACON. VFR DURING THE DAY TODAY EXCEPT IN SHOWERS AND THUNDERSTORMS.
THERE MAY BE CONVECTION AROUND THE FORECAST AREA MUCH OF THE DAY BUT
THE BEST CHANCE FOR THUNDER AT ANY OF THE TAF SITES APPEARS TO BE
18Z AND INTO THE EARLY EVENING. VARIABLE TO LIGHT SOUTHEAST WINDS
THIS MORNING BECOMING SOUTHWEST 10KT AFTER 14Z.

//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON TIMING OF CONVECTION.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.

41

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          64  84  64  84 /  30  40  40  30
ATLANTA         67  83  66  82 /  20  40  40  30
BLAIRSVILLE     60  77  60  78 /  30  60  60  30
CARTERSVILLE    64  84  62  82 /  20  60  60  30
COLUMBUS        68  89  67  87 /  20  30  30  30
GAINESVILLE     65  83  64  81 /  20  50  50  30
MACON           63  87  65  86 /  20  30  30  30
ROME            64  84  61  83 /  30  60  60  30
PEACHTREE CITY  63  85  63  84 /  20  40  30  30
VIDALIA         68  89  69  88 /  40  30  30  30

&&

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

$$

SHORT TERM...30
LONG TERM....SNELSON
AVIATION...41