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.
&&

$$