000 
FXUS62 KFFC 070304
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1000 PM EST FRI DEC 6 2013

.UPDATE...
COLD FRONT CURRENTLY PUSHING THROUGH THE ATLANTA AREA AND SHOULD 
MAKE SLOW PROGRESS SOUTHWARD. LINE OF HEAVY SHOWERS AND ISOLATD 
THUNDERSTORMS ALONG THE FRONTAL BOUNDARY WITH SOME LIGHTER RAIN 
BEHIND THE FRONT. HAVE MADE A FEW TWEAKS TO POPS ACCORDING TO RADAR. 
TEMPERATURES IN NORTHWEST CORNER LOWER THAN FORECAST AND HAVE TRIED 
TO ADJUST THE TEMPERATURE GRIDS TO ACCOUNT FOR THIS. 

41

.PREVIOUS..
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
THE AREA REMAINS IN A WET PATTERN THROUGH THE SHORT TERM. THIS 
AFTERNOON...SCATTERED SHOWERS HAVE DEVELOPED ACROSS THE NORTHERN AND 
WESTERN PART OF THE CWA. MESOANALYSIS SHOWS AREAS IN WESTERN GEORGIA 
WITH 500+ J/KG OF MUCAPE AND 30KTS OF LOW LEVEL WIND SHEAR. 
CONDITIONS ARE STILL IN PLACE FOR THE POSSIBILITY OF ISOLATED SEVERE 
STORMS THIS AFTERNOON AND THE MOST LIKELY AREA REMAINS ACROSS 
WESTERN GEORGIA THIS AFTERNOON INTO TONIGHT. THE THREATS REMAIN 
DAMAGING WIND AND ISOLATED TORNADOES BUT AGAIN ANY SEVERE STORMS 
SHOULD BE ISOLATED. FOR THE SECOND HALF OF TONIGHT THE INSTABILITY 
IS NEAR ZERO AND THE LOW LEVEL SHEAR DECREASES AND THUS THE SEVERE 
THREAT DIMINISHES. WITH THE FRONT SLOWLY SHIFTING SOUTHWARD THE 
BETTER PRECIPITATION COVERAGE WILL MOVE ACROSS THE NORTHERN PORTION 
OF THE CWA OVERNIGHT AND ALTHOUGH THE PRECIPITATION COVERAGE 
DECREASES TOWARDS SUNRISE...SCATTERED SHOWERS SHOULD STILL REMAIN 
ACROSS THE AREA. MAY HAVE SOMEWHAT OF A LULL IN COVERAGE ON SATURDAY 
BUT THEN THE BETTER CHANCES RETURN AGAIN FOR SATURDAY NIGHT ACROSS 
NORTH GEORGIA AS THE WEDGE BUILDS IN. AFTER 06Z 
TONIGHT...INSTABILITY IS NEAR-ZERO SO NO MENTION OF THUNDER AFTER 
TONIGHT...ONLY SHOWERS. THE THREAT FOR SEVERE DIMINISHES 
OVERNIGHT...BUT THEN THE FOCUS TURNS TO RAINFALL AMOUNTS. SEE THE 
HYDRO SECTION FOR MORE DETAILS. 

TEMPERATURES ARE NEAR A MODEL BLEND AND ARE A CHALLENGE WITH THE 
COLD FRONT MOVING IN AND HELPING TO COOL TEMPS BUT THE CLOUDS 
REMAINING IN PLACE AND HELPING TO MODERATE TEMPERATURES. WILL SEE 
CONSIDERABLY COOLER TEMPERATURES ACROSS MOST OF THE CWA TOMORROW AS 
COMPARED TO THE HIGHS TODAY. AROUND A 20 DEGREE DIFFERENCE BETWEEN 
TODAY AND TOMORROW FOR A HIGH TEMP IN ATL. 

11


.LONG TERM /SUNDAY THROUGH FRIDAY/...
MEDIUM RANGE MODEL TRENDS SHOW NO SIGNIFICANT DEPARTURES FROM
RECENT PREVIOUS RUNS. ALTHOUGH COOLER AIR MOVES IN BEHIND THE NEXT
COLD FRONT EARLY NEXT WEEK...UPPER FLOW TURNS ZONAL AT BEST FROM
THE PERSISTENT SOUTHWESTERLY FLOW AND BETTER COLD AIR REMAINS
NORTH OF THE STATE THROUGH NEXT WEEK. SEE PREVIOUS LONG TERM
FORECAST DISCUSSION BELOW.

20

PREV LONG TERM FORECAST DISCUSSION...

LONG TERM /SUNDAY THROUGH THURSDAY/...
/ISSUED 337 AM EST FRI DEC 6 2013/ 
EXTENDED BEGINS WITH SOUTHWEST FLOW CONTINUING ALOFT AS SURFACE
HIGH OVER THE GREAT LAKES CONTINUES RIDGING DOWN THE EASTERN
SEABOARD IN A DIABATICALLY ENHANCED CLASSICAL CAD SETUP.
ISENTROPIC UPGLIDE KEEPS HIGH POP-LOW QPF PRECIP ACROSS THE AREA
EARLY ON SUNDAY BUT AS A STRONG TROUGH AND SURFACE COLD FRONT
APPROACH SUNDAY NIGHT...PRECIPITATION INCREASES ACROSS THE AREA.
SEE HYDRO SECTION BELOW FOR MORE DETAIL.

SOUTH OF THE WEDGE FRONT...AS THE SYNOPTIC COLD FRONT APPROACHES
ON MONDAY...ALL MODELS HAVE MUCAPES INCREASING TO OVER 500 J/KG.
NOT TOO IMPRESSIVE BUT ENOUGH TO KEEP MENTION OF SLIGHT CHANCE
THUNDER IN THE AREA MONDAY AFTERNOON IN THAT WARM SECTOR...WHERE
HIGH TEMPS WILL BE IN THE MID 60S TO MID 70S. BEST SHEAR WILL BE
ALONG AND BEHIND THE COLD FRONT WHERE 0-1KM BULK SHEAR WILL BE
APPROACHING 35KT WHILE 0-6KM SHEAR IS UPWARDS OF 60-70KT. JUST
NOT SURE HOW WELL THESE TWO WILL LINE UP. SO FOR NOW...ISOLATED
THUNDER STILL LOOKS GOOD AND CANNOT RULE OUT STRONG TO ISOLATED
SEVERE STORMS BUT WILL MONITOR FORECAST TRENDS OVER THE NEXT
COUPLE OF DAYS.

COLD FRONT PUSHES THROUGH BY TUESDAY NIGHT BRINGING A MUCH COOLER
AIRMASS TO THE REGION. CURRENT GRIDS REFLECT ONLY A BRIEF OVERLAP
OF THE COLD AIRMASS AND LIGHT PRECIP...BRINGING A RAIN/SNOW MIX
INTO PORTIONS OF NORTH GEORGIA EARLY TUESDAY BEFORE THE MOISTURE
SWEEPS OUT. THIS WILL NEED TO BE REFINED WITH LATER FORECASTS. 00Z
GFS AND ECMWF ARE IN FAIRLY DECENT AGREEMENT THROUGH THE
EXTENDED...WITH HINTS OF THE BEGINNING OF A HYBRID DAMMING EVENT
JUST BEYOND THE END OF THE PERIOD.

TDP


&&

.HYDROLOGY...
A ROUND OF RAIN FORECAST OVERNIGHT COMBINED WITH ADDITIONAL RAIN 
EXPECTED SUNDAY NIGHT INTO MONDAY WILL ALLOW FOR THE POTENTIAL OF 
2.5 TO 5 INCHES OF RAIN ACROSS NORTH GEORGIA THROUGH TUESDAY. 
ISOLATED HIGHER AMOUNTS ARE POSSIBLE. THESE AMOUNTS WILL ALLOW FOR 
POSSIBLE MINOR FLOODING ACROSS NORTH GEORGIA. SEE THE HYDROLOGIC 
OUTLOOK /ESFFFC/ FOR DETAILS. 

11

&&

AVIATION...
00Z UPDATE...
FRONTAL BOUNDARY JUST SOUTH OF RMG WILL CONTINUE TO SINK SLOWLY 
SOUTH. SCATTERED SHOWERS AHEAD OF THE BOUNDARY WILL AFFECT THE TAF 
SITES...BUT MORE WIDESPREAD RAIN SHOULD SPREAD OVER THE TAF SITES 
AFTER FRONTAL PASSGE LATE TONIGHT AND SATURDAY MORNING. ISOLATED 
CONVECTION POSSIBLE BUT TOO DIFFICULT TO TIME FOR THE TAF SITES. 
IFR CEILINGS OVERNIGHT WITH SOME LIFR POSSIBLE THROUGH 14Z. WINDS 
SOUTHWEST 10KT WITH OCCASIONAL GUSTS...BECOMING NORTHWEST 10KT BY 
12Z WITH HIGHER GUSTS. 

41 


//ATL CONFIDENCE...00Z UPDATE...
MEDIUM TO HIGH CONFIDENCE ON WIND. MEDIUM ON ALL OTHER ELEMENTS. 

41

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          56  60  44  48 /  60  60  70  90 
ATLANTA         48  54  45  53 /  90  50  70  80 
BLAIRSVILLE     46  52  41  47 / 100  50  80  90 
CARTERSVILLE    45  52  44  51 / 100  50  80  90 
COLUMBUS        55  58  52  66 /  70  60  50  50 
GAINESVILLE     52  57  43  45 /  80  40  80  90 
MACON           60  63  51  62 /  60  60  50  50 
ROME            45  52  43  52 / 100  50  90  90 
PEACHTREE CITY  49  53  47  57 /  80  50  70  70 
VIDALIA         65  73  54  66 /  30  40  40  30 

&&

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

$$

SHORT TERM...11
LONG TERM....20
AVIATION...41