Area Forecast Discussion
Issued by NWS Atlanta, GA

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000
FXUS62 KFFC 182009
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
409 PM EDT SAT APR 18 2015



.SHORT TERM /TODAY THROUGH MONDAY/...
MAIN STORY IN THE SHORT TERM IS THAT THE RAIN CONTINUES. ZONAL FLOW
ALOFT ACROSS THE CWA WILL BECOME SW TONIGHT AS AN UPPER LEVEL LOW
TRACKS ACROSS THE PLAINS TONIGHT AND IS ABSORBED INTO THE PARENT LOW
TOMORROW. THIS WILL KEEP US IN AN ACTIVE WEATHER PATTERN THROUGH THE
SHORT TERM. SFC LOW LIFTS FROM THE MS VALLEY TONIGHT INTO THE OHIO
VALLEY SUNDAY AND HELPS TO BRING HIGHER RAIN CHANCES BACK TO THE
CWA.

EXPECT THE LIGHT SHOWERS TO CONTINUE ACROSS NORTH GEORGIA THIS
AFTERNOON...BUT AS THE SFC LOW LIFTS NORTHWARD...WIDESPREAD RAIN
WILL RETURN TO THE SW PART OF THE CWA AFTER 00Z TONIGHT AND SPREAD
ACROSS THE NORTHEAST. HI RES MODELS ARE CONSISTENT WITH THIS. WITH
CAPE VALUES AROUND 1000-1500 J/KG AND MINIMAL LOW LEVEL SHEAR...
COULD SEE A STRONG STORM WITH THE CONVECTION AS IT MOVES INTO THE SW
THIS EVENING WITH THE MAIN THREATS BEING WIND AND HAIL. WILL BE
INTERESTING TO SEE THOUGH HOW THE CONVECTION IN THE GULF AFFECTS OUR
CONVECTION TONIGHT/TOMORROW. SEEMS LIKE THE BETTER STRONG TO SEVERE
STORM CHANCES WILL BE TOMORROW WITH MUCAPE VALUES AROUND 1500
J/KG...BUT AGAIN LIMITED SHEAR VALUES. WITH CLOUD COVERAGE...IT MAY
BE HARD TO REALIZE ALL OF THIS INSTABILITY...ALTHOUGH MAY SEE SOME
BREAKS IN THE CLOUDS. EVEN SO...ENOUGH OF A CHANCE OF STRONG TO
SEVERE STORMS TOMORROW THAT SPC HAS THE AREA IN A SLIGHT RISK FOR
SEVERE STORMS WITH THE MAIN THREATS AGAIN WIND AND HAIL. CONVECTION
LOOKS TO BE BEST ACROSS NORTH GEORGIA ON SUNDAY BEFORE 18Z BUT
BETTER ACROSS THE SE DURING THE AFTERNOON. THIS SOUTHEAST AREA MAY
ALSO BE MORE VULNERABLE TO GETTING BREAKS IN THE CLOUDS AND
DESTABILIZING MORE THAN THE REST OF THE AREA. REGARDLESS OF IF OUR
STORMS REACH SEVERE POTENTIAL...SINCE OUR GROUND IS SATURATED...IT
WILL NOT TAKE SEVERE WINDS TO BRING DOWN TREES AND POTENTIALLY CAUSE
DAMAGE.

FOR SUNDAY NIGHT...MAY BE IN A LITTLE BIT OF A DRY SLOT /AT LEAST
COMPARED TO THE REST OF THE SHORT TERM/ SO POPS DECREASE FOR SUNDAY
NIGHT.

SEE THE HYDRO SECTION FOR HYDRO DETAILS.

11


.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
NO MAJOR CHANGES NEEDED TO THE LONG TERM PORTION OF THE FORECAST.

COLD FRONT STILL ON TRACK TO IMPACT THE CWFA ON MONDAY. CAPES ARE
STILL BETWEEN 1000 AND 2000 J/KG DURING PRIME HEATING. MID AND UPPER
LEVEL SUPPORT WILL ALSO BE PRESENT. STEEP MID LEVEL LAPSE RATES AND
A COUPLED JET STRUCTURE WILL AID IN THUNDERSTORM DEVELOPMENT. THE 40-
50KT LLJ IS STILL PRESENT...WITH DECENT LOW LEVEL SHEAR AND HELICITY
ALONG THE COLD FRONT. SO...IF AREAS ALONG AND SOUTH OF THE FRONT ARE
ABLE TO CLEAR OUT AND HEAT UP...THERE WILL BE AND INCREASED
POTENTIAL FOR SEVERE WEATHER. DAMAGING WIND GUSTS AND LARGE HAIL ARE
POSSIBLE. ISOLATED TORNADOES WILL NOT BE OUT OF THE QUESTION.

TUESDAY AND WEDNESDAY SHOULD BE QUIET...AND MOSTLY DRY AS HIGH
PRESSURE BUILDS ACROSS THE REGION.

A FRONT WILL BEGIN APPROACHING FROM THE NORTH LATER ON THURSDAY AND
POTENTIALLY MOVE SOUTH THROUGH THE REMAINDER OF THE FORECAST AREA
THROUGH FRIDAY. LATE THURSDAY INTO FRIDAY WILL BE THE NEXT BEST
CHANCES OF PRECIP AFTER MONDAY.

NLISTEMAA


&&

.HYDROLOGY...
BORDERLINE FOR A FLOOD WATCH AT THIS POINT AND COULD ARGUE
TO GO EITHER WAY WITH IT. DID CUT BACK ON WPC QPF IN THE SOUTHERN
PORTION OF THE CWA IN THE SHORT TERM AS IT LOOKED A LITTLE ON THE
HIGH SIDE. OVERALL THOUGH...LOOKING AT AROUND AN INCH TO AN INCH AND
A HALF BETWEEN TONIGHT AND SUNDAY. THESE AMOUNTS ARE LESS THAN THE
1HR FFG AND WILL OCCUR OVER A LONGER PERIOD OF TIME THAN AN HOUR. AT
THIS POINT WILL HOLD OFF ON A FLOOD WATCH...BUT ITS POSSIBLE ONE MAY
BE NEEDED TO BE ISSUED ON LATER SHIFTS. EVEN WITHOUT THE FLOOD
WATCH...SINCE WE HAVE BEEN SO WET...STILL THE POTENTIAL FOR A FEW
POINTS TO GO INTO FLOOD. WILL CONTINUE TO MONITOR THIS CLOSELY
THOUGH.
&&

AVIATION...
18Z UPDATE...
LIGHT RAIN CONTINUES ACROSS THE ATL TO AHN AREA AND WILL SEE THIS
THROUGH THE AFTERNOON. MAIN AREA OF RAIN WILL MOVE INTO TONIGHT
THOUGH AND THERE IS A CHANCE THAT CSG COULD SEE A THUNDERSTORM IN
THE 00-03Z TIME FRAME THIS EVENING. OTHERWISE...BEST CHANCE OF
THUNDERSTORMS WILL BE LATE TOMORROW MORNING INTO THE AFTERNOON.
WINDS SHOULD REMAIN ON THE EAST SIDE THIS AFTERNOON BUT EXPECT A
SHIFT TO THE SW TOMORROW MORNING.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE.

11

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          75  64  73  63 /  60 100 100  40
ATLANTA         74  65  74  63 /  60 100  90  40
BLAIRSVILLE     73  61  69  59 /  50 100 100  50
CARTERSVILLE    75  64  75  62 /  40 100  80  40
COLUMBUS        77  66  77  65 /  60 100  90  40
GAINESVILLE     75  63  71  62 /  50 100 100  50
MACON           77  66  76  64 /  40  80  90  40
ROME            75  63  76  61 /  40 100  80  40
PEACHTREE CITY  74  64  74  62 /  60 100  90  40
VIDALIA         81  67  80  66 /  40  60  90  50

&&

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

$$

SHORT TERM...11
LONG TERM....NLISTEMAA
AVIATION...11


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