375 FXUS62 KFFC 220720 AFDFFC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 220 AM EST MON DEC 22 2014 .PREV DISCUSSION... /ISSUED 924 PM EST SUN DEC 21 2014/ UPDATE... A FEW MINOR ADJUSTMENTS MADE TO THE SHORT TERM FORECAST GRIDS... MAINLY CONCERNING TEMPERATURE TRENDS THIS EVENING AND A SMALL ADJUSTMENT TO THE OVERNIGHT LOWS. OTHERWISE THE CURRENT GRIDS REMAIN ON TRACK AS BETTER PRECIPITATION COVERAGE PUSHES EAST OF THE AREA. WEDGE STRENGTHENS OVERNIGHT WITH AMPLE LOW-LEVEL MOISTURE FOR SOME SCATTERED LIGHT PRECIPITATION. 20 PREV DISCUSSION... /ISSUED 625 PM EST SUN DEC 21 2014/ SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... DRIZZLY AND DREARY SHORT-TERM IN STORE FOR NORTH AND CENTRAL GEORGIA...AND WILL GIVE WAY TO A MUCH MORE ACTIVE EXTENDED. PROLONGED STRONG ISENTROPIC LIFT WILL PREVAIL THROUGH THE SHORT-TERM PERIOD UNDER SOUTHWEST FLOW ALOFT TO BEGIN THE PERIOD. SURFACE HIGH IN SOUTHEAST CANADA HAS BEGUN TO RIDGE DOWN THE EASTERN SEABOARD IN DIABATICALLY-ENHANCED CLASSICAL CAD ONSET...WITH DAMMING BECOMING FIRMLY ENTRENCHED OVERNIGHT TONIGHT. WIDESPREAD LOW CLOUDS WILL CONTINUE WITH DRIZZLE AND LIGHT RAIN EXPANDING NORTH WITH THE INTRUSION OF GULF MOISTURE OVER THE COLD /WELL...COOL/ DOME TONIGHT. BEST RAIN CHANCES WILL REMAIN ON THE SOUTH AND EAST SIDE OF THE FORECAST AREA...HAVE GONE CATEGORICAL IN THESE AREAS FOR A HIGH-POP LOW-QPF SITUATION...BUT DRIZZLE WILL BE POSSIBLE JUST ABOUT ANYWHERE WITH LOW-LEVEL SATURATION UNDER THE STRENGTHENING INVERSION. POPS LOWER SOMEWHAT ON MONDAY AS FIRST WAVE OF GULF MOISTURE EXITS BUT DEEPENING WAVE OVER THE PLAINS WILL BRING ANOTHER ROUND OF MORE SIGNIFICANT MOISTURE LATE INTO THE DAY INTO MONDAY NIGHT. UPPER DIFFLUENCE WILL ADD SYNOPTIC LIFT BUT DAMMING REMAINS FIRM AT LEAST IN THE NORTHERN HALF OF THE AREA. SHOULD SEE ENOUGH LIFTING OF THE WARM/WEDGE FRONT TO ALLOW PORTIONS OF CENTRAL GEORGIA TO WORK INTO THE WARM SECTOR STARTING LATE MONDAY. HIGH TEMPS MONDAY AFTERNOON WILL BE EXTREMELY DEPENDENT ON HOW FAR THE WEDGE FRONT MAKES IT... BUT FOR NOW HAVE TEMPS BELOW NORMAL FOR NORTHERN 2/3 OF THE AREA BUT NEAR TO PERHAPS SLIGHTLY ABOVE EXTREME SOUTH. THIS WILL OBVIOUSLY HAVE TO BE REEVALUATED TONIGHT TO GET A BETTER HANDLE ON LOCATION OF THE WEDGE FRONT...BUT OBVIOUSLY SOME BUST POTENTIAL THERE. ALL GUIDANCE KEEPS SBCAPE VALUES PRETTY MUCH 0...BUT MUCAPE VALUES DO INCREASE LATE MONDAY NIGHT ACROSS CENTRAL GEORGIA...EXPANDING NORTH WITH THE WARM AIR ADVECTION ALOFT. MUCAPE VALUES OF BETWEEN 200-300 J/KG SPREAD TOWARD THE METRO AREA TOWARD EARLY TUESDAY MORNING. HAVE ADDED ISOLATED THUNDER EXTREME SOUTH TOWARD THE END OF THE PERIOD. WANT TO REITERATE THAT AGAIN THIS IS NOT SURFACE-BASED CAPE SO BASICALLY ONLY EXPECT ISOLATED RUMBLES EMBEDDED WITHIN THE LARGER INCREASING RAIN SHIELD. BY THE END OF THE PERIOD...DEEP PLAINS TROUGH HAS CUTOFF IN TO A MID- LEVEL LOW WITH PRIMARY SURFACE LOW IN THE UPPER MIDWEST BUT SECONDARY SURFACE LOW DEVELOPING OFF THE TEXAS GULF COAST...WITH SOUTHWEST FLOW ALOFT OVER THE SOUTHEAST AND CONTINUED UPPER-LEVEL DIFFLUENCE. POPS INCREASE AGAIN RAPIDLY LATE OVERNIGHT TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING...WITH SOME ACTIVE WEATHER EXPECTED INTO THE EXTENDED. SEE BELOW. TDP LONG TERM /TUESDAY THROUGH SUNDAY/... MODELS IN MORE AGREEMENT WITHIN THEMSELVES THAN PREVIOUS RUNS AND HAVE THEREFORE MADE A FEW CHANGES TO THE TUESDAY/WEDNESDAY STORM BASED ON THE LATEST DATA. HAVE INCREASED POPS TUESDAY INTO WEDNESDAY. THE FOCUS FOR SEVERE WEATHER WILL BE IN TWO WAVES. THE FIRST ON TUESDAY AS INSTABILITY INCREASES ACROSS CENTRAL GA SOUTH OF THE WARM FRONT AND FEEL THIS WILL BE THE AREA OF CONCERN TUESDAY. NORTH GA WILL BE IN THE COLD DOME ON TUESDAY AND ALTHOUGH THERE IS PLENTY OF ISENTROPIC LIFT AND WHILE THERE COULD BE A FEW RUMBLES OF THUNDER...THE COLD DOME SHOULD KEEP NORTH GA OUT OF THE SEVERE WEATHER THREAT. THE SECOND WAVE WILL BE WITH THE COLD FRONT...MOVING INTO THE WESTERN PART OF THE CWA WEDNESDAY MORNING. EXPECT A LINE OF TRW...MAINLY A QLCS WITH ISOLATED TORNADOES/DAMAGING WINDS. THIS LINE SHOULD MOVE RAPIDLY ACROSS THE CWA WEDNESDAY AS WILL THE THREAT OF SEVERE STORMS. THE FRONT/STORMS WILL BE OUT OF THE CWA BY 00Z THU. WITH A MORE PROMINENT WEDGE TUESDAY...HAVE MADE ADJUSTMENTS TO MAX TEMPS TUESDAY. MODELS ARE NOW ADVERTISING A DRIER SYSTEM FOR NEXT WEEKEND AND HAVE BROUGHT DOWN THE POPS JUST A LITTLE. NO OTHER CHANGES ARE PLANNED TO THE LONG TERM. 17 && .AVIATION... 06Z UPDATE... WEDGE IS FIRMLY ENTRENCHED OVER THE STATE WITH LOW CLOUDS AND LIGHT RAIN OR DRIZZLE EVERYWHERE. BASICALLY LOOKING AT IFR TO LIFR CEILINGS THROUGH THIS TAF PERIOD AS THE WEDGE IS HEAR TO STAY FOR AT LEAST ANOTHER 24 TO 36 HOURS. WINDS WILL STAY OUT OF THE EAST WITH SPEEDS IN THE 6-12KT RANGE. VSBYS MAINLY IFR RIGHT NOW BUT THEY SHOULD GET INTO THE MVFR RANGE LATER THIS AFTERNOON. //ATL CONFIDENCE...06Z UPDATE... MEDIUM TO HIGH. 01 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 48 43 48 48 / 60 60 100 100 ATLANTA 51 45 52 52 / 40 50 100 100 BLAIRSVILLE 49 42 48 47 / 50 50 100 100 CARTERSVILLE 52 45 50 50 / 30 40 100 100 COLUMBUS 58 52 65 58 / 40 50 100 100 GAINESVILLE 48 42 46 46 / 50 60 100 100 MACON 54 49 63 58 / 50 50 100 100 ROME 53 46 54 53 / 30 40 100 100 PEACHTREE CITY 52 46 56 54 / 40 50 100 100 VIDALIA 57 52 71 60 / 70 50 100 100 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...01 LONG TERM....41 AVIATION...01