Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 200241 AAB
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
941 PM EST FRI DEC 19 2014

.UPDATE...

WIDESPREAD LIGHT TO OCCASIONALLY MODERATE PRECIPITATION SPREADING
INTO WESTERN PORTIONS OF THE FORECAST AREA THIS EVENING. CURRENT
SHORT TERM FORECAST GRIDS CONTINUE TO HANDLE THESE TRENDS WELL AND
NO SIGNIFICANT CHANGES HAVE BEEN NECESSARY THIS EVENING.

20

&&

.PREV DISCUSSION... /ISSUED 640 PM EST FRI DEC 19 2014/

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
WIDESPREAD CIRRUS HAS ALREADY OVERSPREAD THE AREA WITH ADDITIONAL
CLOUD COVER PUSHING IN. ISENTROPIC LIFT ALSO INCREASING IN ADVANCE
OF DEEPENING SHORTWAVE ACROSS THE SOUTHERN AND CENTRAL PLAINS. HIGH
PRESSURE OVER SOUTHERN CANADA CONTINUES TO RIDGE INTO THE SOUTHEAST
BUT WITH THE DEEPENING SHORTWAVE AND DIFFLUENCE ALOFT A SURFACE LOW
IS DEVELOPING IN THE NORTHWEST GULF WITH MOISTURE SPREADING ACROSS
THE LOWER MISSISSIPPI VALLEY AND INTO THE DEEP SOUTH. DO NOT EXPECT
MUCH IN THE WAY OF QPF...THOUGH 12Z MODELS DID INCREASE THE TOTALS
JUST A TAD...STILL UNDER 0.5 INCHES EVERYWHERE...WITH SOME AREAS
/ESPECIALLY NORTH GEORGIA/ HARDLY SEEING ANY. IT IS ALSO POSSIBLE WE
COULD SEE SOME CONVECTION DEVELOPING ALONG THE NORTHERN GULF COAST
WHICH MIGHT SERVE TO CUT OF DOWNSTREAM PRECIPITATION EVEN MORE. HAVE
CONTINUED TREND OF CATEGORICAL POPS ESPECIALLY ACROSS PORTIONS OF
CENTRAL GEORGIA. PRETTY MUCH 0 INSTABILITY ASSOCIATED WITH THIS
SYSTEM SO CONTINUED ALL RAIN WORDING. LOWS SATURDAY NIGHT...WHILE
ABOVE NORMAL...WILL BE HOVERING JUST ABOVE FREEZING SO CANNOT RULE
OUT SOME BRIEF FLURRIES ESPECIALLY AT ONSET ACROSS NORTH GEORGIA BUT
OVERALL JUST A COLD LIGHT RAIN.

AS THE SHORTWAVE DAMPS ON SATURDAY...NEARLY ZONAL FLOW DEVELOPS
ALOFT WITH SURFACE HIGH SHIFTING EAST INTO EASTERN CANADA. THE HIGH
BEGINS DAMMING DOWN THE EASTERN SEABOARD LATE IN THE SHORT TERM AS
ANOTHER SHORTWAVE MOVES OUT OF THE ROCKIES INTO THE PLAINS. SOME
LIGHT PRECIPITATION MAY LINGER ACROSS CENTRAL GEORGIA LATE IN THE
PERIOD BEFORE THE NEXT WAVE OF MOISTURE PULLS NORTH OUT OF THE GULF
FOR THE BEGINNING OF THE EXTENDED.

WENT WITH A GENERAL BLEND ON TEMPERATURES BUT ESPECIALLY HIGHS
SATURDAY WILL NEED TO BE REEVALUATED...IT IS QUITE POSSIBLE THAT
PRECIPITATION AND EXTENSIVE CLOUD COVER MAY KEEP TEMPERATURES EVEN
LOWER THAN CURRENTLY FORECAST. AS IT IS...EXPECT HIGHS ABOUT NORMAL
AND LOWS HELD SEVERAL DEGREES ABOVE.

TDP

LONG TERM /SUNDAY THROUGH FRIDAY/...
MAINLY TWEAKS TO THE LONG TERM BASED ON THE LATEST GUIDANCE.
THERE IS GROWING CONCERN FOR SEVERE WEATHER TUESDAY AFTERNOON.
BEST CHANCE FOR SOMETHING OTHER THAN RAIN LOOKS TO BE LATE
WEDNESDAY NIGHT IN THE FORM OF FLURRIES OVER FAR N GA.

BDL

PREVIOUS DISCUSSION...
MODEL SOLUTIONS CONTINUE TO SHOW AN ACTIVE
WEATHER PATTERN IN THE LONG TERM... WITH GFS AND ECMWF SHOWING
ANOTHER COOL WEDGE SETTING UP ON SUNDAY AND GETTING OVERRUN WITH A
MOIST MID LEVEL SOUTHERLY FLOW. THIS GETS ENHANCED BY A SERIES OF
WEAK DISTURBANCES IN THE SOUTHWEST FLOW ALOFT AND SHOULD RESULT IN
AREAS OF MAINLY RAIN SPREADING OVER THE AREA SUNDAY AFTERNOON AND
SUNDAY NIGHT. THE WEDGE APPEARS TO HOLD STRONG MONDAY AND MONDAY
NIGHT AS DISTURBANCES CONTINUE TO TRAVERSE THE STATE AND WARRANT A
CHANCE OF RAIN FOR MOST AREAS THROUGH MONDAY NIGHT. AT THIS TIME...
INSTABILITIES AND ANY THUNDER THREAT APPEARS TO REMAIN MAINLY ACROSS
SOUTH GEORGIA MONDAY-MONDAY NIGHT. HOWEVER... THIS CHANGES TUESDAY
AND TUESDAY NIGHT AS MODELS AGREE ON A LONG WAVE TROUGH DEEPENING
OVER THE PLAINS ON TUESDAY... THEN KICKING EAST TUESDAY NIGHT AND
DRAGGING A COLD FRONT ACROSS THE AREA TUESDAY NIGHT-WEDNESDAY
MORNING. AHEAD OF THE APPROACHING TROUGH AND ASSOCIATED COLD
FRONT... ECMWF AND GFS ARE SHOWING 200-600 MUCAPE NOSING UP ACROSS
MAINLY CENTRAL GEORGIA TUESDAY AFTERNOON AND EVENING. THIS COUPLED
WITH MODERATE DEEP LAYER SHEAR AND STRONG DIFFLUENT FLOW ALOFT WILL
WARRANT ADDING MENTION OF ISOLATED THUNDERSTORMS ACROSS MUCH OF
CENTRAL GEORGIA TUESDAY AFTERNOON AND EVENING... BUT SUSPECT THE
THUNDERSTORM THREAT COULD SPREAD INTO PARTS OF NORTH GEORGIA WITH
LATER MODEL RUNS CONSIDERING THE EXPECTED UPPER FORCING. STILL MUCH
UNCERTAINTY ON ANY SEVERE STORM THREAT AS INSTABILITIES AND DEEP
SHEAR REMAIN FAIRLY MODEST FOR NOW... BUT WILL CONTINUE TO MONITOR
FOR THIS POTENTIAL... ESPECIALLY ACROSS PARTS OF CENTRAL GEORGIA
WHERE THE GREATER INSTABILITIES AND SHEAR ARE EXPECTED. BEHIND THE
COLD FRONT...  WRAP AROUND MOISTURE... STRONG UPPER FORCING AND
TEMPS DROPPING INTO THE MID 30S SUGGEST THE POTENTIAL FOR A FEW SNOW
SHOWERS ACROSS MAINLY NORTHEAST GEORGIA WEDNESDAY MORNING... BUT NO
SIGNIFICANT ACCUMULATIONS ARE EXPECTED WITH AIR AND GROUND TEMPS
ABOVE FREEZING. THE SNOW SHOWERS POTENTIAL RETURNS WEDNESDAY NIGHT-
THURSDAY MORNING... BUT WITH MUCH LESS AVAILABLE MOISTURE TO WORK
WITH. OTHERWISE... EXPECT HIGH PRESSURE AND A DRY AIR MASS TO
DOMINATE MOSTLY ON THURSDAY.

AVIATION...
00Z UPDATE...

VFR CONDITIONS CURRENTLY WILL LOWER TO MVFR FROM SOUTHWEST TO
NORTHEAST BETWEEN 06Z AND 12Z. MAINLY MVFR CEILINGS AND VISIBILITIES
CONTINUE THROUGH 18Z BEFORE BEGINNING TO IMPROVE BACK TO VFR FROM
NORTHWEST TO SOUTHEAST BETWEEN 18Z AND 00Z. NORTHWEST TO NORTH WINDS
6KT OR LESS BECOMING NORTH TO NORTHEAST BY 06Z AND NORTHEAST TO EAST
AFTER 12Z. A LARGE AREA OF LIGHT OT OCCASIONALLY MODERATE RAIN
SPREADS NORTHEAST ACROSS THE AREA BETWEEN 00Z AND 06Z...AND ENDS
FROM THE NORTHWEST BETWEEN 18Z AND 00Z.

//ATL CONFIDENCE...00Z UPDATE...

MEDIUM TO HIGH.

20

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          40  51  38  51 /  80  70  20  30
ATLANTA         42  53  42  52 /  80  70  10  30
BLAIRSVILLE     37  49  36  50 /  80  50  20  20
CARTERSVILLE    37  53  37  52 /  80  60  10  20
COLUMBUS        45  55  45  54 / 100  90  20  30
GAINESVILLE     40  50  38  50 /  80  60  20  30
MACON           44  55  43  54 /  90  90  20  30
ROME            37  52  35  53 /  80  50  10  20
PEACHTREE CITY  40  54  37  52 /  90  80  20  30
VIDALIA         47  56  45  56 /  80  80  20  40

&&

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

$$

SHORT TERM...20
LONG TERM....DEESE
AVIATION...20



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