Area Forecast Discussion
Issued by NWS Atlanta, GA

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000 FXUS62 KFFC 191929 AFDFFC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 229 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... 18Z UPDATE... INCREASING CLOUDS THIS AFTERNOON...CIGS WILL BEGIN DROPPING GRADUALLY TONIGHT WITH LOW VFR EXPECTED BY JUST AFTER MIDNIGHT. -RA MOVES IN AFTER MIDNIGHT AS WELL...WITH CIGS DROPPING TO MVFR AROUND OR JUST AFTER 12Z. -RA MOVES OUT BEFORE NOON FOR THE NORTHERN TAFS...CLOSER TO NOON FOR MCN/CSG...AND MVFR CIGS LINGER JUST ABOUT THROUGH THE END OF THE PERIOD FOR ALL BUT ATL. NW WINDS EARLY SHIFTING TO NE AFTER MIDNIGHT /CURRENT TIMING IS 05Z/ AND CONTINUING TO VEER TOWARD E BY THE END OF THE PERIOD. //ATL CONFIDENCE...18Z UPDATE... MEDIUM-HIGH ON TIMING OF ALL ELEMENTS...HIGH ON OCCURRENCE. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 41 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 44 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 36 52 35 53 / 80 50 10 20 PEACHTREE CITY 39 54 37 52 / 90 80 20 30 VIDALIA 47 56 45 56 / 80 80 20 40 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TDP LONG TERM....BDL AVIATION...TDP

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