000 FXUS62 KFFC 071737 AFDFFC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 1237 PM EST SAT DEC 7 2013 .PREV DISCUSSION... /ISSUED 1001 AM EST SAT DEC 7 2013/ UPDATE... REGIONAL RADAR SHOWS A LINE OF BROKEN SHOWERS ALONG A COLD FRONT FROM ABOUT WASHINGTON TO MACON TO COLUMBUS. A MARGINALLY UNSTABLE AIRMASS IS SITUATED SOUTH OF THE BOUNDARY...WITH DEWPOINTS IN THE LOWER TO MIDDLE 60S. HAVE HAD A FEW RUMBLES OF THUNDER THIS MORNING IN THE CONVECTIVE ACTIVITY ALONG THE FRONT...AND SEE NO REASON TO REMOVE THE MENTION OF THUNDER ACROSS THE SOUTHERN/SOUTHEAST CWFA FOR THE AFTERNOON. GOOD TEMPERATURE GRADIENT ACROSS THE CWFA ALSO...AND WILL PROBABLY HAVE TO MAKE SOME HOURLY ADJUSTMENTS. HOWEVER...THE MAX TEMP GRID LOOKS GOOD AND WILL MAKE NO CHANGES. UNLIKE MOST DAYS...SOME OF THE MAX TEMPS...ESPECIALLY ACROSS THE NORTH...HAVE ALREADY OCCURRED. PREV DISCUSSION... /ISSUED 637 AM EST SAT DEC 7 2013/ PREV DISCUSSION... /ISSUED 343 AM EST SAT DEC 7 2013/ TEMPERATURES RANGING FROM UPPER 30S TO MID 70S THIS MORNING... SHORT TERM /TODAY THROUGH SUNDAY NIGHT/... WELL DEFINED COLD FRONT SITUATED THIS MORNING FROM JUST SOUTH OF COLUMBUS TO ATHENS. STILL SEEING A BAND OF LIGHT SHOWERS AHEAD OF THE FRONT BUT INTENSITY NO WHERE NEAR WHAT WAS PRESENT LATE LAST EVENING. AVAILABLE POTENTIAL ENERGY IS JUST NOT THERE TO SUPPORT ANY STORM FORMATION AND SHORT TERM MODELS SUCH AS THE RAP INDICATE THIS TREND TO CONTINUE THROUGH THE REMAINDER OF THE OVERNIGHT HOURS. NORTH OF THE FRONT...TEMPERATURES ARE FALLING RAPIDLY WITH UPPER 30S ALREADY ENTERING INTO THE NORTHWEST CORNER. FOR THE REMAINDER OF TODAY...EXPECT FRONTAL BOUNDARY HAS MADE JUST ABOUT AS MUCH PROGRESS AS IT IS GOING TO AS UPPER LEVEL FLOW REMAINS SW AND SURFACE HIGH BEGINS TO BRIDGE WELL NORTH OF THE AREA. THIS WILL LEAVE BAN OF BEST MOISTURE IN PLACE ACROSS PORTIONS OF CENTRAL GA BUT NOT READY TO DROP POPS COMPLETELY FOR THE NORTHERN TIER. FOR AREAS ALONG AND NORTH OF THE ATLANTA METRO...HIGH TEMPS HAVE LIKELY ALREADY BEEN REACHED FOR THE DAY WITH A DROP TO CONTINUE THROUGH 14Z AND THEN MARGINAL WARMING THEREAFTER. FOR TONIGHT...CLASSIC CAD EVENT BEGINS ITS DEVELOPMENT WITH WEDGING THROUGH THE PIEDMONT OF THE CAROLINAS AND JUST EXTREME EAST GA INITIALLY. WEDGE WILL THEN BEGIN ITS EASTWARD EXPANSION FROM THE 06Z TO 12Z TIMEFRAME WHILE SOUTH AND SOUTHWEST FLOW CONTINUES ABOVE 975MB. THIS WILL ALLOW FOR A GOOD ISENTROPIC UPGLIDE SETUP AND WITH MOISTURE UP TO 10K FEET...SHOULD HAVE NO PROBLEMS GENERATING WIDESPREAD PRECIP SHIELD ACROSS THE NORTHERN TIER. MODELS REALLY FOCUSING ON AREAS NORTH OF ATL METRO BUT WITH WEDGE IN PLACE AND LIKELY TO BE A STRONGER INFLUENCE THAN MODELS PROJECT...WOULD EXPECT HIGHER POPS FURTHER SOUTH. AS WEAK UPPER LEVEL DISTURBANCE APPROACHES THE AREA SUNDAY AND CAD CONTINUES ITS INFLUENCE...SHOULD SEE PRECIP MAINTAIN ITS DISTRIBUTION ACROSS NORTH GEORGIA. ENOUGH SOUTHERLY FLOW SOUTH OF THE FRONT SUN AFTERNOON TO GENERATE LOW END CAPE VALUES. NOTHING TO GET TOO EXCITED ABOUT AT THIS POINT BUT SHOULD BE SUFFICIENT FOR ISOLATED THUNDER IN THE GRIDS. DEESE LONG TERM /MONDAY THROUGH FRIDAY/... GFS AND ECMWF IN REASONABLE AGREEMENT THROUGH THE EXTENDED...SHOWING THE COLD FRONT PUSHING INTO NORTHWEST GEORGIA EARLY MONDAY...STALLING THROUGH EARLY TUESDAY AS THE LONGWAVE TROUGH FLATTENS...AND FINALLY PUSHING OUT LATE TUESDAY AS A REINFORCING SHORTWAVE SLIDES THROUGH THE OHIO VALLEY. SOME CONCERN STILL REMAINS FOR THUNDER POTENTIAL MONDAY AFTERNOON WITH MUCAPES BETWEEN 500-700J/KG...BUT BEST CAPE IS DISPLACED FROM THE DEEP LAYER SHEAR THAT WOULD REALLY SUPPORT ORGANIZATION SO AT THIS TIME NOT REALLY ANY CONCERN ABOUT STRONG TO SEVERE POTENTIAL. TODAYS RUNS ARE SLOWING DOWN THE SURFACE CAA BEHIND THE FRONT EARLY TUESDAY...SO TUESDAY MORNING LOW FORECAST IS NOT QUITE AS COLD AS YESTERDAY...AND THUS HAVE REMOVED THE RAIN/SNOW MIX ACROSS NORTH GEORGIA. CANNOT RULE OUT ADDITIONAL SEE-SAWING OVER THE NEXT COUPLE OF DAYS DEPENDING ON HOW THE TEMPERATURE FORECAST CHANGES BUT IN ANY CASE ANY RESULTING MIXED PRECIP WOULD BE LIGHT AND SHORT-LIVED AT BEST...NOT REALLY ENOUGH TO WORRY ABOUT HAZARDS. WEDNESDAY AND THURSDAY CURRENTLY SPORTING A MAINLY DRY FORECAST WITH THE EXCEPTION OF A WAVE PUSHING THROUGH THE SOUTHERN PLAINS INTERACTING WITH THE SUBTROPICAL JET ACROSS THE SOUTHERN TIER OF THE COUNTRY. SHORTWAVE ACROSS THE DESERT SOUTHWEST EARLY FRIDAY BEGINS LIFTING INTO THE SOUTHERN PLAINS DURING THE DAY...INDUCING SURFACE LOW DEVELOPMENT IN THE NORTHWEST GULF AND SPREADING PRECIP ACROSS THE SOUTH. WE JUST SEE THE BEGINNINGS OF THIS IN THE CURRENT 7-DAY FORECAST...AND GFS IS A TAD FASTER...BUT BOTH MODELS HAVE THIS COASTAL LOW ADVERTISED AND HAVE THE ADDED SUPPORT OF RUN-TO-RUN CONSISTENCY. COULD DEFINITELY SEE ANOTHER ROUND OF HEAVY PRECIP JUST BEYOND THE END OF THE PERIOD. TDP HYDROLOGY... FOR THE EXTENDED...QPF TOTALS BEGIN TO TAPER OFF A BIT BUT STILL HAVE ANOTHER 0.5-0.75 INCH DURING THE DAY ON MONDAY WITH ADDITIONAL LIGHT RAIN MONDAY NIGHT AND EARLY TUESDAY AS THE OCCLUDED SYSTEM STRETCHES...FINALLY DRYING OUT ON WEDNESDAY. STORM TOTAL QPF FROM TODAY THROUGH TUESDAY BRINGS ANOTHER 2-3 INCHES ACROSS NORTH GEORGIA. && .AVIATION... 18Z UPDATE... NW FLOW WILL SWITCH AROUND TO EASTERLY EARLY THIS EVENING AS THE HIGH PRESSURE WEDGE BUILDS DOWN THE SPINE OF THE APPALACHIANS. THE EASTERLY FLOW WILL ADVECT COPIOUS LOW LEVEL MOISTURE INTO THE AREA...AND CIGS ARE EXPECTED TO DIP TO 004-006. CIGS SHOULD REMAIN DOWN THROUGH TOMORROW BTWN 006-009. VBYS WILL BE REDUCED IN LIGHT RAIN/DRIZZLE OVERNIGHT. DRIZZLE SHOULD END AS THE RAIN PICKS UP ON SUNDAY. //ATL CONFIDENCE...18Z UPDATE... MEDIUM CONFIDENCE ALL ELEMENTS. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 63 43 47 43 / 50 100 100 100 ATLANTA 60 45 52 47 / 40 100 100 80 BLAIRSVILLE 54 41 47 44 / 20 90 100 100 CARTERSVILLE 50 45 49 45 / 20 90 100 90 COLUMBUS 66 52 64 59 / 60 80 70 40 GAINESVILLE 60 41 46 42 / 30 100 100 100 MACON 69 51 59 53 / 60 80 70 60 ROME 50 44 50 47 / 20 60 100 100 PEACHTREE CITY 60 47 53 50 / 60 100 90 60 VIDALIA 71 54 63 57 / 60 70 50 40 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$