Area Forecast Discussion
Issued by NWS Atlanta, GA

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000 FXUS62 KFFC 190254 AAD AFDFFC AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 1054 PM EDT FRI APR 18 2014 .UPDATE...
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ALTHOUGH WINDS HAVE BEEN SLOW TO COME UP...I STILL EXPECT OCCASIONAL PERIODS OF GUSTY WINDS AT OR OVER ADVISORY CRITERIA THROUGH THE OVERNIGHT AS THE SURFACE LOW LIFTS OUT OF THE GULF AND MOVES ACROSS FAR SOUTH GEORGIA. I HAVE EXTENDED THE TIME OF THE ADVISORY ACROSS CENTRAL GEORGIA TO MATCH THE ADVISORY AREA TO THE NORTH...12Z. OTHERWISE NO OTHER SIGNIFICANT CHANGES MADE AT THIS TIME. 20
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&& .PREV DISCUSSION...
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/ISSUED 925 PM EDT FRI APR 18 2014/ UPDATE... HAVE MADE SOME ADJUSTMENTS TO THE SHORT TERM FORECAST GRIDS...MAINLY MINOR...TO FIT CURRENT AND EXPECTED TENDS. STILL EXPECTING MODERATE RAIN TO CONTINUE OVER THE FLOOD WATCH AREA FOR THE REMAINDER OF THE EVENING INTO THE EARLY MORNING SO NO CHANGES ARE PLANNED FOR THE FLOOD WATCH AT THIS TIME. WINDS ARE SLOW TO COME UP BUT I DO STILL EXPECT A GRADUAL INCREASE THROUGH THE EVENING. FORECAST VALUES ARE BORDERLINE FOR THE WIND ADVISORY...HOWEVER WITH VERY MOIST SOIL AND TREES THAT ARE WELL INTO THE LEAFING OUT PROCESS...I THINK THAT IT REMAINS ADVISABLE TO KEEP THE WIND ADVISORIES GOING. 20 PREV DISCUSSION... /ISSUED 745 PM EDT FRI APR 18 2014/ UPDATE... WE HAVE DECIDED TO EXPAND THE FLOOD WATCH NORTHWARD TO INCLUDE MOST OF THE ATLANTA METRO AREA INTO NORTHEAST GEORGIA...ROUGHLY NORTHWARD TO JUST NORTH OF THE I-85 CORRIDOR...BASED ON RADAR/SATELLITE TRENDS DEPICTING THE PERSISTENT DEFORMATION ZONE PRECIPITATION ASSOCIATED WITH THE UPPER LOW. WE WILL LIKELY SEE A QUICK 1 TO 2 INCHES OF ADDITIONAL RAIN THROUGH THE EVENING ACROSS THE WATCH AREA. ALTHOUGH THIS IS NOT LIKELY TO CAUSE WIDESPREAD FLOODING ISSUES IN THE NEW WATCH AREA...THERE IS LIKELY TO BE AT LEAST ISOLATED TO SCATTERED PROBLEMS OVERNIGHT. 20 PREV DISCUSSION... /ISSUED 300 PM EDT FRI APR 18 2014/ SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... OF COURSE THE MAIN STORY THROUGH THE SHORT TERM IS THE RAIN. CLASSICAL CAD REMAINS IN PLACE RIDGING DOWN THE EASTERN SEABOARD BUT IS IN THE PROCESS OF ERODING AS A STRONG UPPER WAVE MOVES ACROSS THE SOUTHEAST...DEEPENING AND STRENGTHENING TO A CLOSED OFF LOW. A SURFACE REFLECTION IS MOVING OUT OF THE GULF OF MEXICO AND INTO THE FLORIDA PANHANDLE AT AFD TIME...AND IT SHOULD WORK ITS WAY EAST NORTHEAST GENERALLY ALONG THE FLORIDA-GEORGIA BORDER. WIDESPREAD GULF MOISTURE CONTINUES TO STREAM ACROSS THE SOUTHEAST. CONVECTION IN FLORIDA IS ORIENTED NORTH-SOUTH /INSTEAD OF EAST-WEST/ SO IS NOT ACTING TO CUT OFF ANY INFLOW...RATHER...IF ANYTHING...THE CONVECTIVE ACTIVITY AND ASSOCIATED LATENT HEAT RELEASE IS LIKELY CONTRIBUTING TO OVERALL ATMOSPHERIC MOISTURE CONTENT. A BIT OF DRY-SLOTTING LEADING TO A REDUCTION IN RAIN ACROSS SOUTHWEST GEORGIA TOWARD TALLAHASSEE...WITH HEFTY AMOUNTS ACROSS ALABAMA UNDERNEATH THE UPPER WAVE ASSOCIATED WITH THE DEFORMATION AXIS. WILL PROBABLY SEE SOME OF THE DRY-SLOTTING MOVE ACROSS THE SOUTHERN TIER OF OUR AREA BUT AS THE ENTIRE SYSTEM MOVES EAST ALL HIRES AND SYNOPTIC GUIDANCE BRINGS THIS DEFORMATION ZONE ACROSS CENTRAL GEORGIA. SEE HYDRO SECTION BELOW FOR MORE ON QPF. WITH THE WIDESPREAD RAIN...TEMPERATURES TODAY HAVE HELD PRETTY STEADY IN THE LOWER TO MID 50S WITH WARMEST AREAS IN NORTHWEST GEORGIA WHERE CLOUD COVER IS A LITTLE THINNER AND NOT QUITE AS MUCH RAIN REACHING THE GROUND JUST YET DUE TO THE DRY DEWPOINTS. EVAPORATIVE COOLING CONTRIBUTING TO THIS AS WELL. SHOULD DEFINITELY SEE RECORD COLD HIGH AT CSG FOR TODAY AND STILL FLIRTING WITH IT AT MCN. SO WITH THAT...NOT A HUGE DIURNAL RANGE FOR TONIGHT BUT SHOULD STILL GET INTO THE 40S EVERYWHERE EXCEPT POSSIBLY EXTREME SOUTHEAST ZONES WHERE THEY STAY NEAR 50 OR LOWER 50S. /WITH THE DEFORMATION AXIS SETTING UP FOR TONIGHT IMAGINE IF IT WERE 15 DEGREES COLDER...YIKES./ DEFINITELY WARMER ON SATURDAY STILL 10 OR SO DEGREES BELOW NORMAL. SHOULD SEE AN AREA OF LINGERING PRECIP ACROSS THE AREA AT LEAST THROUGH 18Z AS SURFACE FLOW SHIFTS OFF THE ATLANTIC BRINGING ADDITIONAL LOW-LEVEL MOISTURE TO THE AREA. CLOUD COVER ASSOCIATED WITH THE UPPER LOW WILL LINGER THROUGH THE REST OF THE DAY SATURDAY WITH POPS LINGERING OVERNIGHT THROUGH EXTREME SOUTHEAST ZONES. STRONG SURFACE INVERSION REMAINS IN PLACE WITH THE DAMMING. JUST OFF THE SURFACE HOWEVER...925MB WINDS ARE PROGGED UPWARDS OF 60KT ACROSS SOME OF THE AREA. EVEN WITH THE INVERSION TO KEEP THIS JET JUST OFF THE SURFACE...THERE WILL CONTINUE TO BE ENOUGH OF A SURFACE GRADIENT TO WARRANT KEEPING THE WIND ADVISORY IN PLACE. EXPECT WINDS TO INCREASE THIS EVENING AND OVERNIGHT ESPECIALLY ACROSS CENTRAL GEORGIA. NORTHERN EXTENT OF ADVISORY IS IFFY BUT BETTER TO HAVE IT OUT THAN NOT. OTHER CONCERN IS POSSIBILITY OF THUNDER ACROSS THE AREA. JUST A LITTLE MUCAPE CREEPING INTO SOUTHERN ZONES AT AFD TIME BUT DO NOT EXPECT MUCH MORE THAN THAT THIS EVENING AND TONIGHT WITH THE WIDESPREAD RAIN AND CLOUD COVER. CANNOT RULE OUT ISOLATED THUNDER ON SATURDAY AS THE LAPSE RATES INCREASE IN RESPONSE TO THE UPPER LOW MOVING ACROSS...SO HAVE INCLUDED ISOLATED THUNDER WORDING FOR EXTREME SOUTHEAST ZONES. TDP LONG TERM /SUNDAY THROUGH FRIDAY/... MAINLY ONLY TWEAKS TO THE FORECAST BASED ON THE LATEST GUIDANCE. FORECAST MLCAPES NOW RUNNING 400-1000 FROM THE GFS AT 18Z TUESDAY WITH NO SIGNIFICANT SHEAR WITH THE FRONT. BDL PREVIOUS DISCUSSION... MAIN CLOSED LOW JUST OFF THE GA/CAROLINA COAST STAYS FAIRLY STATIONARY THROUGH SUN AND MON BEFORE WEAKENING AND PUSHING FURTHER OUT TO SEA TUE. CLOUDS WILL LINGER ACROSS THE AREA SUN WITH MAYBE A FEW LIGHT SHOWERS SUN MORNING ACROSS SOUTHEASTERN SECTIONS OF THE CWA. MODELS ARE IN VERY GOOD AGREEMENT THROUGH MOST OF THE EXTENDED WITH MINOR DIFFERENCES IN TIMING AND AVAILABLE MOISTURE WITH NEXT SYSTEM TUE. 00Z MON...A SHORTWAVE OVER THE MIDDLE OF THE COUNTRY DEVELOPS INTO A CLOSED LOW CENTER AND MOVES OVER THE GREAT LAKE STATES BY 00Z TUE. ITS TRAILING COLDS FRONT SWEEPS THROUGH THE MISSISSIPPI RIVER VALLEY AND INTO NA GA BY 12Z TUE. WILL SEE SHOWER AND THUNDERSTORMS SWEEP THROUGH THE STATE TUE AND COULD SEE SOME FAIRLY STRONG STORMS AS INSTABILITY INDICES ARE INCREASING MODEL RUN TO MODEL RUN. 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. THIS FRONT SHOULD BE EAST OF THE STATE BY 00Z TO 06Z WED WITH HIGH PRESSURE BUILDING BACK IN FOR WED AND THU. 01 HYDROLOGY... PORTIONS OF CENTRAL GEORGIA /AMERICUS AND AREAS WEST/ HAVE ALREADY RECEIVED AND INCH OF RAIN THROUGH 18Z TODAY. MIGHT BE PERIODS OF BRIEF REDUCTION IN ACTIVITY ACROSS THAT SOUTHERN BORDER WITH THE DRY-SLOTTING REACHING INTO THE FORECAST AREA...BUT WITH THE DEFORMATION AXIS MOVING ACROSS THE AREA THAT AREA OF HEAVIER RAIN IN ALABAMA /WHERE THEY HAVE RECEIVED BETWEEN 1.5-2 INCHES/...EXPECT QPF TOTALS TO BE PRETTY HEFTY THIS EVENING AND OVERNIGHT. NEW STORM TOTAL FROM AFD TIME TILL THE END OF THE EVENT BRINGS AN ADDITIONAL 2 INCHES /BASIN-AVERAGE/ TO SOUTHERN ZONES...WITH SOME AREAS SOUTHEAST OVER 2.5 INCHES. OTHER CONCERN IS THAT RADARS ARE UNDERESTIMATING BY ABOUT 15 PERCENT TODAY...NOT A WHOLE LOT BUT ENOUGH TO BE AWARE OF. WITH THIS PROLONGED...WIDESPREAD RAIN WILL DEFINITELY SEE SOME PROBLEMS ON AREA WATERWAYS ESPECIALLY ACROSS CENTRAL GEORGIA. LOCATION AND TIMING OF FLOOD WATCH ALREADY IN PLACE LOOKS GOOD. IT MAY GO A LITTLE LONG BUT WE CAN ALWAYS CANCEL EARLY WHEN RAIN MOVES OUT. TDP 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... SOLID AREA OF IFR TO MVFR CONDITIONS ACROSS CENTRAL GEORGIA WITH A TIGHT NORTH-SOUTH GRADIENT FROM IFR/MVFR TO VFR ACROSS NORTH GEORGIA. I DO EXPECT MVFR AND EVENTUALLY IFR CONDITIONS TO EXPAND NORTHWARD ACROSS ALL TAF SITES WITH ALL SITES IFR BY 06Z. SHOULD SEE IMPROVEMENT TO MVFR MOST AREAS AFTER 12Z...CONTINUING THROUGH 00Z. WINDS WILL REMAIN NORTHEASTERLY THROUGH THE PERIOD STARTING 6-14KT WITH GUSTS 14-24KT...INCREASING TO 10-18KT WITH GUSTS 17-29KT BY 06Z. WIDESPREAD LIGHT TO MODERATE RAIN...WITH EMBEDDED SHOWERS... WILL CONTINUE AREAWIDE THROUGH 06Z...DIMINISHING FROM WEST TO EAST THROUGH THE REMAINDER OF THE FORECAST PERIOD. //ATL CONFIDENCE...00Z UPDATE... MEDIUM. 20
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&& .PRELIMINARY POINT TEMPS/POPS... ATHENS 45 60 48 71 / 100 70 20 10 ATLANTA 46 62 49 70 / 100 50 20 5 BLAIRSVILLE 44 62 47 72 / 80 50 10 5 CARTERSVILLE 47 64 50 72 / 100 30 10 5 COLUMBUS 48 63 51 73 / 100 30 10 5 GAINESVILLE 46 60 49 70 / 100 60 20 5 MACON 48 61 51 72 / 100 50 20 5 ROME 48 65 49 73 / 70 20 10 5 PEACHTREE CITY 47 62 49 71 / 100 50 10 5 VIDALIA 52 64 54 70 / 100 50 40 20 && .FFC WATCHES/WARNINGS/ADVISORIES...
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FLOOD WATCH THROUGH SATURDAY EVENING FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BIBB...BLECKLEY...BUTTS...CARROLL... CHATTAHOOCHEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD... CRISP...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FORSYTH...GLASCOCK...GREENE...GWINNETT...HALL...HANCOCK... HARRIS...HEARD...HENRY...HOUSTON...JACKSON...JASPER... JEFFERSON...JOHNSON...JONES...LAMAR...LAURENS...MACON... MADISON...MARION...MERIWETHER...MONROE...MONTGOMERY...MORGAN... MUSCOGEE...NEWTON...NORTH FULTON...OCONEE...OGLETHORPE...PEACH... PIKE...PULASKI...PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON... SPALDING...STEWART...SUMTER...TALBOT...TALIAFERRO...TAYLOR... TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...WALTON... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. WIND ADVISORY UNTIL 8 AM EDT SATURDAY FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY...BUTTS... CARROLL...CHATTAHOOCHEE...CHEROKEE...CLARKE...CLAYTON...COBB... COWETA...CRAWFORD...CRISP...DAWSON...DEKALB...DODGE...DOOLY... DOUGLAS...EMANUEL...FAYETTE...FLOYD...FORSYTH...GLASCOCK... GREENE...GWINNETT...HALL...HANCOCK...HARALSON...HARRIS...HEARD... HENRY...HOUSTON...JACKSON...JASPER...JEFFERSON...JOHNSON... JONES...LAMAR...LAURENS...LUMPKIN...MACON...MADISON...MARION... MERIWETHER...MONROE...MONTGOMERY...MORGAN...MUSCOGEE...NEWTON... NORTH FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...PUTNAM...ROCKDALE...SCHLEY... SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT... TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP... TWIGGS...UPSON...WALTON...WARREN...WASHINGTON...WEBSTER... WHEELER...WHITE...WILCOX...WILKES...WILKINSON.
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&& $$ SHORT TERM...20 LONG TERM....39 AVIATION...20

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