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000
FXUS62 KFFC 192325
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
725 PM EDT WED JUN 19 2013



.UPDATE...
WEAK SURFACE BOUNDARY SITUATED ACROSS THE SOUTHERN CWFA THIS
EVENING. CONVECTION HAS FIRED ALONG THE TROUGH...BUT SHOULD
CONTINUE TO DIMINISH IN STRENGTH AND COVERAGE THROUGH THE EVENING.
ADDITIONAL SHOWERS HAVE POPPED UP ACROSS THE HIGHER TERRAIN TO THE
NORTH. ALSO EXPECT THIS ACTIVITY TO DIMINISH/WEAKEN WITH THE LOSS
OF DAYTIME HEATING...BUT FOR NOW HAVE ADDED ISOLATED POPS TO THE
NORTHER TIER OF ZONES.

&&

.PREV DISCUSSION... /ISSUED 309 PM EDT WED JUN 19 2013/

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
LARGE SCALE UPPER PATTERN TRANSITIONING TO A MORE SUMMER-LIKE
PATTERN THROUGH THE SHORT TERM FORECAST PERIOD ACROSS THE EASTERN
U.S. AS A LARGE...BROAD...BUT FAR FROM DOMINATING...UPPER RIDGE
BUILDS EASTWARD OUT OF THE MISSISSIPPI VALLEY. THROUGH THURSDAY
NIGHT...THE MAJORITY OF THE MEDIUM AND SHORT RANGE MODELS SHOW
LINGERING WEAK UPPER TROUGHINESS ACROSS THE REGION UNDER THE
LARGER SCALE UPPER RIDGE. THIS WILL KEEP THE UPPER RIDGE FROM
SUPPRESSING ALL CONVECTION OVER THE FORECAST AREA...HOWEVER
EASTERLY LOW-LEVEL FLOW AROUND A BUILDING SURFACE RIDGE ANCHORED
ALONG THE EAST COAST KEEPS INSTABILITY SOMEWHAT LIMITED. BEST
CHANCES FOR PRECIPITATION WILL BE ACROSS OUR SOUTHERN ZONES IN THE
VICINITY OF THE OLD FRONTAL BOUNDARY...AND CONVECTION WILL
MAINTAIN A DECIDEDLY DIURNAL BIAS.

20

LONG TERM /FRIDAY THROUGH WEDNESDAY/...
WITH THE LAST TWO ECMWF RUNS SHOWING BETTER PRECIP FOR THE SECOND
HALF OF THE WEEKEND INTO NEXT WEEK...WHICH IS IN LINE WITH THE
GFS...HAVE INCREASED POPS FOR SUNDAY THROUGH WEDNESDAY TO BRING
ALL OF THE CWA INTO THE CHANCE CATEGORY. PREVIOUS DISCUSSION IS
BELOW.

11

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
GUIDANCE IS IN FAIRLY DECENT CONSENSUS WITH MAIN FEATURES OF THE
LONG TERM. MUCH OF THE FORECAST PERIOD WILL BE DOMINATED BY BROAD
UPPER RIDGING AND A 1025-MB SFC HIGH SLIDING OFF THE MID-ATLANTIC
COAST RESULTING IN HYBRID CAD SETTING UP ACROSS THE AREA THROUGH
THE END OF THE WEEK AND INTO THE WEEKEND. WITH LITTLE ISENTROPIC
UPGLIDE EXPECTED ACROSS THE WEDGE...MAIN IMPACT LOOKS TO BE TO
LIMIT DEVELOPMENT ACROSS PORTIONS OF THE EAST AND FOCUS MAINLY
DIURNALLY DRIVEN CONVECTION ALONG OR NEAR THE PERIPHERY OF THE
WEDGE. HAVE CONTINUED TO ADVERTISE CHANCE POPS ALONG THE SOUTHERN
TIER OF THE AREA...AND IN PORTIONS OF THE FAR NORTH FOR ANY
OROGRAPHIC ENHANCEMENT...OTHERWISE SLIGHT POPS ELSEWHERE. ENOUGH
INSTABILITY FORECAST TO MAINTAIN THUNDERSTORM POTENTIAL
THROUGHOUT...EVEN IF SLIGHT CHANCE.

THERE CONTINUES TO BE DISCREPANCIES ON THE AMOUNT OF MOISTURE ACROSS
THE AREA. THE GFS BRINGS A SLUG OF ENHANCED DEEP LAYER MOISTURE INTO
THE AREA FROM THE SOUTHEAST ON SATURDAY AND LINGERS ON THROUGH EARLY
NEXT WEEK...WHILE THE ECMWF IS MUCH MORE LIMITED. HAVE DECIDED TO
KEEP POPS ON THE LOW END AND KEEP BEST CHANCES ALONG SOUTHERN TIER
AND FAR NORTH UNTIL MORE CONSENSUS IS REACHED AND CAN JUSTIFY ANY
RAISING OF POPS IN THE FUTURE. TEMPS SHOULD GENERALLY BE NEAR TO
SLIGHTLY ABOVE NORMAL WITH LITTLE CHANGE FROM DAY TO DAY THROUGH THE
PERIOD.

BAKER

&&

.AVIATION...
00Z UPDATE...
EARLIER MODELS WERE SHOWING SOME MVFR CIGS DEVELOPING AT ATL
OVERNIGHT. NEWER RUNS HAVE BACKED OFF A BIT SO HAVE MADE THE BKN
DECK A SCT ONE. DIURNAL CU WILL DEVELOP TOMORROW AND DECKS SHOULD
BE BTWN 4KFT AND 5KFT. WINDS WILL BE LIGHT EASTERLY
OVERNIGHT...BUT WILL PICK UP DURING THE AFTERNOON THURSDAY. GUSTS
TO AROUND 15KT WILL BE POSSIBLE.

//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON CIGS...HIGH CONFIDENCE REMAINING ELEMENTS.

NLISTEMAA

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          66  87  66  87 /  20  20  20  20
ATLANTA         68  87  68  85 /  20  20  20  20
BLAIRSVILLE     61  84  60  80 /  20  20  20  30
CARTERSVILLE    64  89  63  87 /  20  20  20  20
COLUMBUS        71  91  70  89 /  30  30  20  30
GAINESVILLE     67  84  66  83 /  20  20  20  20
MACON           69  88  69  87 /  30  30  20  30
ROME            64  88  63  88 /  20  20  20  20
PEACHTREE CITY  67  87  66  86 /  20  20  20  20
VIDALIA         70  88  70  88 /  30  40  20  30

&&

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

$$

UPDATE...NLISTEMAA