Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 172328 AAA
AFDFFC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
730 PM EDT THU APR 17 2014


.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
MAIN CONCERN IS WITH QPF AS AN AREA OF LOW PRESSURE ALLOWS FOR
OVERRUNNING GULF MOISTURE AGAINST A STRONG CLASSICAL CAD WEDGE FROM
A PARENT 1040+MB SFC HIGH SLIDING OFF THE NEW ENGLAND COAST. MODELS
ARE AT LEAST IN GOOD AGREEMENT WITH THE UPPER LEVELS CLOSING OFF A
LOW AND ENHANCING THE FORCING FOR WIDESPREAD PRECIP MAINLY FRIDAY
AFTERNOON INTO FRIDAY NIGHT. THERE ARE SOME DECENT DISCREPANCIES
WITH THE TRACK OF THE SFC LOW AND AMOUNT OF MOISTURE. THE LAST 2
RUNS OF THE GFS HAVE BEEN FARTHER NORTH AND QUITE ROBUST ON
QPF...WHILE THE NAM HAS BEEN FARTHER SOUTH AND DRIER...WITH THE
ECMWF A BIT OF A COMPROMISE BETWEEN. SEE HYDROLOGY SECTION BELOW FOR
MORE ON QPF AND INCREASING FLOOD THREAT.

FOR POPS AND WEATHER...HAVE TRENDED ONSET OF LIKELY POPS IN THE
SOUTHWEST CWA SOONER THAN GUIDANCE AS ISENTROPIC UPGLIDE TYPICALLY
ALLOWS FOR PRECIP BEFORE THE MODEL SOLUTIONS. HAVE RAMPED UP AFTER
06Z TONIGHT AND SPREAD INTO DEFINITE POPS ACROSS CENTRAL DURING
DAYTIME FRIDAY WITH LIKELY TO CHANCE INTO NORTH GA. WEDGE SHOULD
KEEP ENVIRONMENT STABLE SO LEFT OUT THUNDER MENTION. OVERALL
CONFIDENCE IN EVOLUTION OF THIS SYSTEM IS NEAR MEDIUM AS SOME MODELS
ARE INDICATING A DRY SLOT NOSING INTO SOUTHERN PORTIONS OF THE AREA
FOR FRIDAY NIGHT AND OVERALL COVERAGE OF SHOWERS MAY BE INCREASED IN
PARTS OF NORTH GA WITH ANY BANDING THAT OCCURS IN THE DEFORMATION
ZONE OF THE LOW AS IT PUSHES SOUTH AND EAST OF THE CWA. HAVE TRENDED
LIKELY AND CHANCE POPS TO EASTERN PORTIONS LATE FRIDAY NIGHT WITH
WRAP-AROUND MOISTURE KEEPING SOME CHANCE POPS LINGERING INTO THE
START OF THE LONG TERM.

FOR TEMPS...TRICKY FORECAST FOR FRIDAY WITH INFLUENCE OF WEDGE AND
MOISTURE OVERRUN. HAVE LEANED AWAY FROM MOS AND TRENDED COOLER
THOUGH NOT AS EXTREME AS RAW GFS. LOOKING AT MANY AREAS STAYING IN
THE MID TO UPPER 50S FOR HIGHS...AND NEAR RECORD LOW MAX VALUES FOR
COLUMBUS AND MACON /POSSIBLY ATHENS/.

BAKER

.HYDROLOGY...
HPC GUIDANCE LOOKS LIKE A REASONABLE COMPROMISE FROM THE VAST
SPECTRUM OF OTHER MODEL QPF SOLUTIONS. THIS BRINGS 2 TO 2.5 INCHES
PROGGED IN A 24-HR PERIOD ACROSS MUCH OF CENTRAL GA AND IS CLOSER TO
THE ECMWF AND SREF...WHILE THE GFS IS ROBUST WITH UP TO 4 INCHES IN
THE SW...AND THE NAM IS ANOMALOUSLY DRY. HAVE GONE WITH A FLOOD
WATCH BASED ON THESE RAISED UPDATED AMOUNTS GENERALLY ALONG AND
SOUTH OF A HAMILTON TO FORSYTH TO WARRENTON LINE. ONE COULD ARGUE
THE BETTER THREAT IS A BIT FARTHER SOUTH WHERE RECENT RAINFALL HAS
BROUGHT AMOUNTS TO 100-200 PERCENT OF NORMAL AND ABOVE NORMAL 7 DAY
STREAM FLOWS...THOUGH UNCERTAINTY WITH POSSIBLE HIGHER AMOUNTS
FARTHER NORTH WEIGHED INTO THE CURRENT WATCH EXTENT. THIS WILL BE IN
AFFECT FROM 12Z FRIDAY TO 12Z SATURDAY.

BAKER


.LONG TERM /SATURDAY THROUGH THURSDAY/...
CLOSED UPPER LOW DISCUSSED ABOVE WILL BE SLOW TO MOVE OUT OF
REGION SAT AND EVEN EARLY SUN. GOOD MODEL AGREEMENT ON H5/SFC
HEIGHT AND WIND FIELDS THOUGH LESS AGREEMENT WITH QPF. UPPER LOW
FCST OVER SOUTHCENTRAL GA 12Z SAT WITH 12Z GFS SLIGHTLY NORTH OF
MEDIAN OF MODEL SOLUTIONS AND 12Z ECMWF FURTHEST SOUTH. BY 12Z SUN
UPPER LOW PROGGED ONLY TO MOVE 500NM OFF GA COAST. CLOUDS WILL
LINGER LATE SAT AND EVEN THRU EARLY SUN IN ERN COUNTIES. COULD
ALSO SEE SOME LINGERING LIGHT RAIN THRU SAT AS WELL. WITH THE
CLOUDS AND LOW THICKNESS VALUES...TEMPS WILL REMAIN BELOW AVERAGE
SATURDAY WITH A QUICK REBOUND NEXT WEEK.

NEXT SYSTEM STILL LOOKING INTERESTING WITH WEAK SHORTWAVE IN WNWLY
FLOW ALOFT PROGGED TO AFFECT AREA ON TUES. UNUSUAL TO SEE THIS
KIND OF PATTERN IN LATE APRIL. WITH MORE MOISTURE AND STRONGER
LIFT...MIGHT SEE A LINE OF STORMS OR MCS. TEMPS WILL BE A LITTLE
ABOVE NORMAL AND WITH DEWPOINTS IN THE 50S AND LOW 60S...MLCAPE
VALUES WILL BE SUFFICIENT FOR SOME STRONG STORMS. DEEP SHEAR WILL
BE SOMEWHAT WEAK...0-6KM BULK SHEAR ONLY 10 TO 15 KTS. WILL
CONTINUE TO MONITOR.

SNELSON


&&


CLIMATE...

RECORDS FOR FRIDAY APRIL 18...

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAHN      90 1942     54 1902     64 1969     32 1936
                1927
   KATL      87 2002     50 1983     69 1927     33 1997
                1937
                1896
   KCSG      91 2002     62 1983     69 2006     37 1962
                                                    1956
   KMCN      90 1967     55 1921     66 1922     33 2001
                1955

RECORDS FOR SATURDAY APRIL 19...

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAHN      91 1917     51 1984     64 1927     30 1983
   KATL      88 1941     50 1983     66 1927     30 1983
   KCSG      91 2002     59 1983     68 1995     33 1983
                            1953
   KMCN      91 2002     59 1910     66 1927     31 1983
                1976
                1968


&&

AVIATION...
00Z UPDATE...
VFR CONDITIONS ARE EXPECTED TO DOMINATE THROUGH 06Z WITH MVFR
CEILINGS SPREADING FROM SOUTHWEST TO NORTHEAST BETWEEN 06Z AND 12Z.
MVFR CEILINGS AND VISIBILITIES ARE EXPECTED TO PREDOMINATE BY 12-15Z
AS WIDESPREAD SHOWERS SPREAD ACROSS THE REGION. LOCAL IFR OR LOWER
CEILINGS AND VISIBILITIES ARE POSSIBLE IN HEAVIER SHOWERS AFTER
18Z...HOWEVER CHANCES NOT HIGH ENOUGH TO INCLUDE AT ANY OF THE TAF
SITES YET. EAST WINDS WILL CONTINUE...GENERALLY 6-10KT THROUGH
08Z...INCREASING TO 10-14KT WITH GUSTS OVER 20KT BY 18Z.

//ATL CONFIDENCE...00Z UPDATE...
MEDIUM ON TIMING FOR ONSET OF MVFR CEILINGS AND PRECIPITATION...HIGH
CONFIDENCE OTHERWISE.

20

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          47  56  46  62 /  20  60  70  30
ATLANTA         50  55  47  62 /  30  60  60  20
BLAIRSVILLE     41  55  44  65 /  10  50  60  20
CARTERSVILLE    47  58  48  66 /  20  50  50  20
COLUMBUS        53  56  49  65 /  90 100  60  30
GAINESVILLE     47  54  47  61 /  20  60  60  30
MACON           52  55  48  63 /  50 100  80  40
ROME            46  60  47  68 /  20  40  40  10
PEACHTREE CITY  48  55  46  63 /  50  70  60  30
VIDALIA         53  59  53  67 /  50  90  90  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM FRIDAY MORNING THROUGH SATURDAY MORNING FOR THE
FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CHATTAHOOCHEE...
CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...
HANCOCK...HARRIS...HOUSTON...JEFFERSON...JOHNSON...JONES...
LAURENS...MACON...MARION...MONROE...MONTGOMERY...MUSCOGEE...
PEACH...PULASKI...SCHLEY...STEWART...SUMTER...TALBOT...TAYLOR...
TELFAIR...TOOMBS...TREUTLEN...TWIGGS...UPSON...WARREN...
WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKINSON.

&&

$$

SHORT TERM...BAKER
LONG TERM....SNELSON
AVIATION...BAKER








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