Issued by NWS Atlanta, GA
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS62 KFFC 221039 AFDFFC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 539 AM EST SUN NOV 22 2009 .UPDATE...-- Changed Discussion --EASTERLY FLOW HAS BROUGHT COOLER TEMPERATURES THAN ANTICIPATED. TWEAKING FIRST PERIOD TEMPERATURES BASED UPON CURRENT TRENDS.-- End Changed Discussion --&& .PREV DISCUSSION...-- Changed Discussion --/ISSUED 515 AM EST SUN NOV 22 2009/ SHORT TERM /TODAY THROUGH TUESDAY/... SHORT TERM MODELS HAVE INITIALIZED THE UPPER LEVEL LOW WELL... AND ARE BETTER AGREEMENT WITH THE TRACK AS IT LIFTS NORTHEAST ACROSS MS/AL/GA THROUGH THIS EVENING BEFORE BECOMING ABSORBED IN THE LONGWAVE FLOW MONDAY MORNING. MODELS ARE ALSO IN BETTER AGREEMENT AS FAR AS HANDLING THE UPPER LOW DEEPENING OVER THE NORTHERN PLAINS SUNDAY NIGHT AND EARLY MONDAY...ALTHOUGH SOME DISCREPANCIES CREEP IN BY MONDAY NIGHT...MAINLY ECMWF IS DEEPER AND A BIT FURTHER EAST WHICH IS IN LINE WITH THE CANADIAN. SURFACE LOW TRACKS ALONG THE GULF COAST TODAY BEFORE SHIFTING ACROSS FLORIDA/SOUTH GEORGIA TONIGHT INTO THE ATLANTIC BY EARLY TOMORROW MORNING. GFS/NAM INDICATE A MESOHIGH DEVELOPS OVER THE CAROLINAS TODAY REINFORCING THE DEVELOPING HYBRID DAMMING ACROSS THE AREA. SHORT TERM MODELS HAVE BACKED OFF THE RAINFALL ASSOCIATED WITH THIS INITIAL SYSTEM...AS EASTERLY FLOW AND HYBRID WEDGE SETS UP TODAY...COOL STABLE FLOW WILL INHIBIT THUNDERSTORM DEVELOPMENT. RAINFALL AMOUNTS ARE EXPECTED TO BE AROUND ONE INCH OR LESS AS WELL SO NO FLOODING CONCERNS ARE ANTICIPATED. LIGHT RAIN WILL CONTINUE THROUGH MONDAY. ALL MODELS HOLD ON TO EASTERLY FLOW AND WEDGE CONDITIONS ON MONDAY AND TUESDAY...WITH GOOD LOW LEVEL MOISTURE THROUGH THE END OF THE PERIOD. EXPECT LIGHT RAIN/DRIZZLE E TO TAPER OFF TUESDAY WITH LINGERING LOW LEVEL CLOUDS THROUGH THE DAY. HOW LONG THE CLOUDS LINGER WILL IMPACT AFTERNOON HIGHS WITH LARGE DISCREPANCIES NOTED IN THE MAV/MET TEMPERATURES IN THE LATER PERIODS DUE TO THE TIMING OF THE EROSION OF THE WEDGE...CSG HAS A 15 DEGREE DIFFERENCE BETWEEN THE TWO ON TUESDAY. WILL START WITH A MAV/MET BLEND AT THIS TIME AS GFS TENDS TO ERODE THE DAMMING TOO QUICK. TEMPERATURES ARE GOING TO BE PROBLEMATIC THROUGH THE FORECAST PERIOD. GUIDANCE TEMPERATURES FOR TODAY ARE SEVERAL DEGREES COOLER THAN CURRENT TEMPERATURES. MODELS SHOWING COOLER EAST FLOW SETTING UP FASTER THAN IT CURRENTLY IS...THUS WILL GO PRETTY CLOSE TO CURRENT TEMPERATURES FOR TODAY...ANTICIPATING THEM TO REMAIN FAIRLY STEADY OR SLOWLY DROP THIS MORNING AND CONTINUE FALLING THIS AFTERNOON AND OVERNIGHT. LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A BROAD UPPER LEVEL TROUGH DOMINATES THE EXTENDED PORTIONS OF THE FORECAST PERIOD...BOTH ECMWF AND GFS ARE FAIRLY CLOSE SPINNING IT NEAR THE GREAT LAKES AREA WITH A SECONDARY LOBE DROPPING OUT OF CANADA WEDNESDAY. ECMWF AND CANADIAN MODELS ABSORB THE SECOND LOW BY THURSDAY WHILE GFS ROTATES THE SECOND LOW ACROSS THE LOWER OHIO VALLEY THURSDAY AND INTO NEW ENGLAND FRIDAY. BOTH MODELS PUSH A WEAK SURFACE FRONT ACROSS THE SOUTHEAST WEDNESDAY...GFS IS DRIER THAN ECMWF WHICH IS DRIER THAN IT WAS YESTERDAY. BASED UPON THIS WILL KEEP EXTENDED PERIODS DRY FOR NOW WITH COOLER THAN NORMAL TEMPERATURES LATER IN THE WEEK. SURFACE HIGH PRESSURE BEGINS BUILDING INTO THE AREA FOR NEXT WEEKEND. AVIATION... COOL WEDGE STRENGTHENING OVER GA THIS MORNING AS SHOWN BY INCREASING EASTERLY WINDS. RAIN WILL CONTINUE TO SPREAD NORTHWARD AS LOW PRESSURE CURRENTLY NEAR MS COAST MOVES EAST TODAY. CEILINGS WILL LOWER TO IFR BY NOON WITH VISIBILITY GENERALLY 3 TO 5SM IN RAIN. CONVECTION SHOULD BE CONFINED TO AREAS SOUTH OF COLUMBUS TO MACON. WINDS WILL REMAIN EAST TO NORTHEAST 10 TO 15KT WITH OCCASIONAL GUSTS TO 20 TO 15KT.-- End Changed Discussion --&& .PRELIMINARY POINT TEMPS/POPS...-- Changed Discussion --ATHENS 50 43 54 44 63 / 80 50 20 5 5 ATLANTA 52 44 55 45 61 / 80 50 20 5 5 BLAIRSVILLE 43 41 49 40 60 / 70 50 40 5 5 CARTERSVILLE 52 44 55 44 60 / 80 50 40 5 5 COLUMBUS 53 45 62 47 65 / 80 30 5 5 5 GAINESVILLE 49 42 52 43 60 / 80 50 40 5 5 MACON 53 45 62 44 65 / 80 30 5 5 5 ROME 54 46 56 44 61 / 70 50 40 5 10 PEACHTREE CITY 53 43 56 42 61 / 80 40 20 5 5 VIDALIA 53 45 66 45 66 / 80 60 5 5 5-- End Changed Discussion --&& .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 12
