Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 220208 AAB
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1008 PM EDT SUN SEP 21 2014

.UPDATE...
CONVECTION CONTINUES TO SLIDE SOUTHWARD ACROSS NORTH GEORGIA AND
THERE IS SOME UNCERTAINTY IN HOW THE PRECIP WILL PLAY OUT LATE
TONIGHT INTO MONDAY. OVERALL HAVE CHOSEN TO SHOW IT CONTINUING TO
SINK SOUTHWARD...BUT DECREASE THE COVERAGE FROM SCATTERED TO
ISOLATED OVERNIGHT. HRRR EXPANDS AREA OF PRECIP BY 14Z WHILE THE
LOCAL WRF ISNT QUITE THAT BOLD. CONSIDERING HRRR HAS BEEN OVERDONE
THIS SUMMER OVERALL...HAVE LEANED MORE TOWARDS THE LOCAL WRF. POP
GRIDS MAY STILL BE A TAD UNDERDONE THOUGH FOR LATE TONIGHT INTO
MONDAY.

MADE A SLIGHT INCREASE IN POPS ACROSS THE FAR SOUTHEAST PART OF
THE CWA FOR MONDAY AFTERNOON AS VORT MAX MAY HELP TO INCREASE
CONVECTION.

&&

.PREV DISCUSSION...

SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
/ISSUED 317 PM EDT SUN SEP 21 2014/
COLD FRONT IS PUSHING INTO THE TENNESSEE VALLEY AT AFD TIME WITH
ISOLATED SHOWERS DEVELOPING ALONG AND JUST AHEAD OF IT. CAPE VALUES
ARE ON THE LOW END...GENERALLY BELOW 1500 J/KG ACROSS NORTH
GEORGIA...AND BEST PVA IS ACTUALLY BEHIND THE FRONT AND DOES NOT
PUSH INTO GEORGIA REALLY UNTIL MONDAY SOMETIME. SO HAVE KEPT TREND
OF SLIGHT TO LOW CHANCE POPS WITH WORDING LIMITED TO ONLY SLIGHT
CHANCE THUNDER...ESPECIALLY SINCE WHAT CAPE MIGHT BE AROUND THIS
AFTERNOON QUICKLY DECREASES OVERNIGHT. DRY AIR STARTS FILTERING INTO
NORTH GEORGIA BEHIND THE FRONT BUT NEW RUNS ARE A LITTLE SLOWER WITH
THIS SO LOW TEMPS TONIGHT NOT FORECAST QUITE AS COOL AS WITH EARLIER
FORECASTS.

CONVECTION SHOULD FIRE ACROSS CENTRAL GEORGIA MONDAY AFTERNOON AND
WITH A PRETTY STRONG VORT LOBE SWINGING AROUND WITH THE SHARP TROUGH
ALOFT...EXPECT TO SEE A LITTLE MORE CONVECTIVE DEVELOPMENT THEN.
MUCAPES INCREASE TO BETWEEN 800-1500 J/KG ACROSS CENTRAL GEORGIA
TOMORROW DEPENDING ON WHICH MODEL ONE USES /NAM IS HIGHER AS USUAL/.
STILL HAVE LOW TO MID-RANGE CHANCE POPS AT BEST BUT WILL HAVE TO
REEVALUATE THIS OVERNIGHT.

DEEP-LAYER CAA BEHIND THE FRONT IS PRETTY IMPRESSIVE ESPECIALLY
EARLY TOMORROW ACROSS NORTH GEORGIA...THOUGH THE CAA MODERATES EVER
SO SLIGHTLY IN THE AFTERNOON. SHOULD SEE A MARKED DIFFERENCE IN
TEMPERATURES BEHIND THE FRONT TOMORROW /5-10 DEGREES COOLER EXCEPT
ACROSS SOUTHERN ZONES WHERE THE FRONT WILL NOT HAVE QUITE MADE IT
THROUGH YET/ AND ESPECIALLY TOMORROW NIGHT /ANOTHER 5-10 DEGREES
COOLER THAN TONIGHT AGAIN EXCEPT FOR SOUTHERN ZONES/. THE DECREASE
IN HUMIDITY WILL ALSO BE VERY NOTICEABLE. ENJOY THE BEAUTIFUL FALL
WEATHER!

TDP

LONG TERM /TUESDAY THROUGH SUNDAY/...
/ISSUED 317 PM EDT SUN SEP 21 2014/
HIGH PRESSURE AND COOLER TEMPERATURES WILL DOMINATE MUCH OF THE
EXTENDED FORECAST PERIOD.

HIGH PRESSURE SITUATED ACROSS THE CENTRAL OHIO VALLEY ON TUESDAY
WILL SLOWLY SHIFT EASTWARD THROUGH THE WEEK. PROLONGED EASTERLY FLOW
OFF OF THE ATLANTIC WILL HELP INCREASE THE CLOUD COVER BY WEDNESDAY.
IN ADDITION...THE OLD FRONTAL BOUNDARY ACROSS NORTH-CENTRAL FLORIDA
WILL BEGIN TO PUSH NORTHWARD AS A WARM FRONT BY LATE WEDNESDAY INTO
EARLY THURSDAY. ISENTROPIC LIFT WILL BEGIN TO INCREASE ACROSS THE
SOUTHEAST ZONES BY THE END OF THE WEEK AND SPREAD W THROUGH THE
WEEKEND. INSTABILITY LOOKS MINIMAL...BUT AN ISOLD THUNDERSTORM
CANNOT BE RULED OUT.

NLISTEMAA

AVIATION...
00Z UPDATE...
/ISSUED 737 PM EDT SUN SEP 21 2014/
MAIN FEATURE TO WATCH TONIGHT WILL BE PRECIPITATION. ALTHOUGH
THERE IS A LINE OF STORMS MOVING INTO NW GEORGIA TONIGHT...EXPECT
THE COVERAGE TO DIMINISH SOME BEFORE MAKING IT TO THE ATL AREA.
SOME SCATTERED SHOWERS STILL POSSIBLE THOUGH AS IT MAKES IT INTO
THE ATL AREA. AT THIS POINT...WILL MONITOR AND IF THE LINE HOLDS
TOGETHER WILL AMEND FOR SHRA FOR A SHORT PERIOD OF TIME.

//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON CIGS. HIGH CONFIDENCE ON VSBYS AND WIND.

11

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          64  81  56  79 /  30  20   0   0
ATLANTA         64  80  57  79 /  30  20   0   0
BLAIRSVILLE     56  74  48  76 /  30   5   0   0
CARTERSVILLE    60  78  52  80 /  30   5   0   0
COLUMBUS        68  84  59  83 /  20  20   0   0
GAINESVILLE     63  77  55  77 /  30   5   0   0
MACON           65  85  58  83 /  20  30   0   0
ROME            60  79  50  81 /  30   0   0   0
PEACHTREE CITY  62  80  52  80 /  20  20   0   0
VIDALIA         66  88  64  83 /   5  40  30  10

&&

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

$$

SHORT TERM...11
LONG TERM....SNELSON
AVIATION...11





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