736 
FXUS62 KFFC 091817
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
217 PM EDT THU APR 9 2015



.PREV DISCUSSION... /ISSUED 1139 AM EDT THU APR 9 2015/ 

UPDATE...
HAVE MADE A FEW MINOR ADJUSTMENTS TO THE FORECAST TO ACCOUNT FOR
LATEST WARMING TRENDS. HAVE PUSHED THE AFTERNOON HIGHS UP A DEGREE
OR TWO...PUTTING ATLANTA CLOSER TO BUT STILL BELOW THE RECORD HIGH
FOR TODAY. OVERALL HI-RES MODELS CONTINUE SHOW ENOUGH CHANCE FOR
AN ISOLATED STORM THIS AFTERNOON TO LEAVE CURRENT POPS IN PLACE.
WILL LOOK MORE CLOSELY AT MAKING MORE SIGNIFICANT ADJUSTMENTS WITH
THE AFTERNOON FORECAST PACKAGE.

31

PREV DISCUSSION... /ISSUED 731 AM EDT THU APR 9 2015/ 

PREV DISCUSSION... 

SHORT TERM /TODAY THROUGH FRIDAY/...
/ISSUED 357 AM EDT THU APR 9 2015/ 
FOCUS OF THE SHORT TERM IS ON A COLD FRONT THAT WILL PUSH THROUGH 
THE CWA ON FRIDAY. AHEAD OF THIS FRONT...THE UPPER LEVEL FLOW WILL 
TRANSITION FROM ZONAL TO MORE SW...AND THIS ALIGNS WITH THE SW FLOW 
AT THE SFC. QUITE A DIFFERENCE TODAY BETWEEN MODELS IN TERMS OF THE 
ACCUMULATED PRECIP. NAM IS ON THE DRIER SIDE WHILE THE GFS IS ON THE 
WET SIDE AND THE ECMWF AND SREF ARE IN THE MIDDLE. HI-RES MODELS ARE 
SUGGESTING ISOLD DEVELOPMENT TODAY. FOR THE MOST PART IN THE 
FORECAST...ENDED UP WITH SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS 
BEGINNING THIS AFTERNOON. WITH INSTABILITY VALUES AROUND 1500-2000 
J/KG...IF STORMS DO DEVELOP...COULD NOT COMPLETELY RULE OUT AN 
ISOLATED STRONG TO SEVERE STORM. 

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONT MOVE INTO NW 
PART OF THE CWA BY SUNRISE ON FRIDAY. WITH THE FRONT MOVING THROUGH 
ON FRIDAY HAVE CONTINUED WITH THE LIKELY TO CATEGORICAL RAIN 
CHANCES. INSTABILITY ON FRIDAY RANGES FROM 1500-2500 J/KG ACROSS THE 
GFS AND NAM...SO PLENTY OF INSTABILITY ACROSS THE CWA. LOW LEVEL AND 
DEEP LAYER SHEAR ARE ON THE LOWER SIDE. HIGHEST 0-1KM HELICITY 
VALUES ARE RIGHT AROUND 12Z ACROSS THE NW WITH GFS FORECAST VALUES 
JUST EXCEEDING 200. NAM IS LOWER AROUND THIS TIME AND DEPICTS THE 
HIGHER VALUES EARLIER IN THE NIGHT AND AGAIN DURING THE DAY FRIDAY 
AS THE FRONT COMES THROUGH. SPC HAS THE NW IN THE MARGINAL FOR DAY 1 
AND THE AREA IN A COMBINATION OF MARGINAL AND SLIGHT RISK FOR DAY 2. 
EXPECT A LINE OF THUNDERSTORMS AHEAD OF THE FRONT AND EVEN THOUGH 
THE SHEAR IS ON THE LOWER SIDE...PLENTY OF INSTABILITY THAT THE CWA 
COULD SEE A FEW STRONG TO SEVERE STORMS ON FRIDAY. THE MAIN THREATS 
CONTINUE TO BE WIND AND HAIL. 

FORECAST HIGH TEMPERATURES FOR TODAY CONTINUE TO REMAIN WELL ABOVE 
NORMAL...WITH THE FORECAST AROUND 2-3 DEGREES BELOW THE RECORDS. FOR 
FRIDAY MORNING...FORECAST IS TO TIE THE WARMEST MIN TEMP FOR THE DAY 
AT ATL AND ONE DEGREE ABOVE THE WARMEST MIN TEMP AT AHN. WITH FRONT 
MOVING IN ON FRIDAY...HIGH TEMPERATURES DECREASE AND THUS NO NEAR 
RECORD TEMPS.

11

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
/ISSUED 357 AM EDT THU APR 9 2015/ 
MODELS IN GOOD AGREEMENT THROUGH THIS WEEKEND...THEN TIMING AND
STRENGTH DIFFERENCES OCCUR FOR THE REST OF THE LONG TERM. HAVE
THEREFORE BROAD BRUSHED POPS NEXT WEEK DUE TO UNCERTAINTY. FOR
THIS WEEKEND THE COLD FRONT WILL LINGER ACROSS SOUTH GA/NORTH FL
KEEPING A CHANCE OF SHOWERS ACROSS THE SOUTHERN COUNTIES IN OUR
CWA THROUGH SUNDAY. THEN AS THE H5 LOW MOVES INTO THE SOUTHERN
PLAINS EARLY NEXT WEEK...WE GET INTO A SOUTHWEST FLOW WHICH WILL
SPREAD MOISTURE ACROSS THE CWA BRINGING A HIGHER CHANCE OF
SHOWERS/TSTORMS.

17

CLIMATE...

RECORDS FOR 04-09

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAHN      89 1919     48 2003     67 1999     32 2000    
                                                    1972    
   KATL      86 2011     47 1899     68 1999     32 2000    
                1995        1896                            
   KCSG      89 1978     56 1989     70 1999     34 2000    
   KMCN      91 1978     53 1916     69 1999     32 2000    
                            1899                            

&&

.AVIATION...
18Z UPDATE...
VFR CONDITIONS EXPECTED THROUGH MUCH OF THE OVERNIGHT
PERIOD...WITH MVFR ACCOMPANYING THE FRONT AND LINE OF CONVECTION PUSHES
INTO NORTHWEST GEORGIA BETWEEN 09-12Z...AND THEN INTO THE ATL AREA
GENERALLY 15-18Z...AND THEN THE CSG AND MCN AREAS 20Z-00Z. CLEARING
CONDITIONS ARE EXPECTED BEHIND THE CONVECTION. SW WINDS EXPECTED
THROUGH THE PERIOD WITH SPEEDS 10-15KT TODAY...3-7KT
OVERNIGHT...AND THEN 8-10KT AFTER 14Z. GUSTY AND VRB WINDS
EXPECTED WITH THE CONVECTION. A SHIFT TO THE NW IS EXPECTED 00Z
SATURDAY OR AFTER.

//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE THROUGH 14Z. MEDIUM CONFIDENCE THEREAFTER.

31

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          87  66  80  56 /  30  30  70  60 
ATLANTA         85  66  78  57 /  20  20  70  60 
BLAIRSVILLE     81  62  71  47 /  30  50  80  20 
CARTERSVILLE    86  65  75  51 /  20  50  80  30 
COLUMBUS        88  65  81  61 /  20  20  50  70 
GAINESVILLE     83  65  75  54 /  30  40  80  40 
MACON           88  65  82  63 /  20  10  40  70 
ROME            85  65  75  50 /  20  50  80  20 
PEACHTREE CITY  85  64  79  55 /  20  20  70  70 
VIDALIA         87  65  86  66 /  10  10  30  60 

&&

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

$$

SHORT TERM...31
LONG TERM....SNELSON
AVIATION...31