241 FXUS62 KFFC 040056 AFDFFC AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 856 PM EDT FRI APR 3 2015 .UPDATE... HAVE COORDINATED WITH SPC AND ISSUED A SVR WATCH FOR PORTIONS OF NORTHWEST GEORGIA...IN EFFECT THROUGH 1 AM SATURDAY. A SWATH OF HIGHER CAPE VALUES...NEAR 1000 J/KG...ACROSS THE WATCH AREA IS EXPECTED TO SUPPORT STRONG STORMS AS THEY MOVE INTO THE STATE IN THE NEXT FEW HOURS. THESE STORMS ARE STILL EXPECTED TO DIMINISH IN INTENSITY AS THEY MOVE INTO THE METRO ATLANTA AREA. 31 && .PREV DISCUSSION... /ISSUED 804 PM EDT FRI APR 3 2015/ .SEVERE STORMS LIKELY FAR NORTHWEST GEORGIA THIS EVENING... SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... /ISSUED 344 PM EDT FRI APR 3 2015/ MODELS CONTINUE TO AGREE ON A COLD FRONT PUSHING INTO NW GA BETWEEN 10 PM AND MIDNIGHT... WITH NUMEROUS SHOWERS AND THUNDERSTORMS DEVELOPING ALONG AND AHEAD OF THE FRONT. THIS WOULD PUSH THUNDERSTORMS INTO NW GA AROUND 6-7 PM THIS EVENING... THEN SPREADING ACROSS THE REST OF NORTH GA DURING THE EVENING... THEN INTO PARTS OF CENTRAL GA AFTER MIDNIGHT. THE STORMS COULD INITIALLY BE STRONG TO POSSIBLY SEVERE AS THEY PUSH INTO NW GA THIS EVENING AS MODELS SHOW STRONG DEEP LAYER SHEAR AND MODERATE CAPES JUST AHEAD OF THE APPROACHING FRONT. SPC CONTINUES TO SHOW A SLIGHT CHANCE OF SEVERE STORMS ACROSS NW GA THIS EVENING... AND MODEL PROFILES SUGGEST THE GREATEST THREAT SHOULD BE MAINLY ALONG AND NW OF A ROME TO CHATSWORTH LINE BETWEEN 7 PM AND MIDNIGHT. STORMS COULD REMAIN RATHER STRONG SOUTH AND EAST OF THIS LINE DURING THE EVENING... BUT A WEAKENING TREND IS EXPECTED INTO LATE EVENING AND AFTER MIDNIGHT AS THE UPPER DISTURBANCE TRACKS WELL TO THE NORTH WHILE INSTABILITY DROPS OFF RATHER QUICKLY IN THE EVENING WITH LOSS OF DAYTIME HEATING. THE MAIN STORM THREATS IN NW GA THIS EVENING WILL BE STRONG DOWNBURST WINDS AND LARGE HAIL... BUT CANNOT RULE OUT AN ISOLATED TORNADO WITH SUCH STRONG WIND SHEAR VALUES NOTED JUST AHEAD OF THE FRONT. THE LINE OF WEAKENING CONVECTION SHOULD PUSH INTO THE ATLANTA METRO AREA BETWEEN MIDNIGHT AND 2 AM SAT MORNING... THEN CONTINUE SOUTHWARD INTO THE COLUMBUS AND MACON AREAS BETWEEN 2 AM AND 6 AM SATURDAY MORNING. ALTHOUGH PATCHY AREAS OF LIGHT RAIN MAY LINGER THROUGH MID SATURDAY MORNING BEHIND THE COLD FRONT... THE THUNDERSTORM THREAT WILL GREATLY DIMINISH BY 3-4 AM SATURDAY FOR ALL AREAS. RAINFALL AMOUNTS FROM THIS EVENING THROUGH SATURDAY MORNING SHOULD AVERAGE AROUND ONE INCH ACROSS NORTH GA... AND ONE HALF INCH OR LESS ACROSS CENTRAL GA... SO NO WIDESPREAD FLOOD PROBLEMS EXPECTED. EXPECTING CLEARING SKIES ON SATURDAY... WITH GUSTY NORTHWEST WINDS WELL INTO THE AFTERNOON. LATEST MODEL DATA HOLDS WIND SPEEDS JUST UNDER WIND ADVISORY CRITERIA FOR NOW... BUT WOULD NOT BE SURPRISED IF THE MIDNIGHT SHIFT POST A WIND ADVISORY FOR SATURDAY IF TONIGHT'S MODEL RUN COMES IN A BIT STRONGER BEHIND THE FRONT. THE COLD AIR ADVECTION PATTERN WILL HOLD SATURDAY HIGHS IN THE 60S NORTH... 70S CENTRAL. LOWS SATURDAY NIGHT PLUMMET INTO THE 30S AND 40S... WITH SOME SPOTTY FREEZING TEMPS LIKELY IN THE NE GA MOUNTAINS BY SUNDAY MORNING. THE CLEAR SKIES AND LIGHT WINDS WILL ALSO BE CONDUCIVE FOR AREAS OF FROST DEVELOPING SUNDAY MORNING ELSEWHERE... SO MAKE PLANS TO PROTECT SENSITIVE OUTDOOR PLANTS SATURDAY NIGHT-SUNDAY MORNING. 39 LONG TERM /SUNDAY THROUGH FRIDAY/... /ISSUED 344 PM EDT FRI APR 3 2015/ NO SIGNIFICANT FEATURES OR EVENTS TO KEY IN ON DURING THE LONG TERM PERIOD. WILL SEE WARM/MOIST ADVECTION EVENT MONDAY MORNING LITTLE DEEP CONVECTION OR INSTABILITY EXPECTED. COULD SEE SOME ELEVATED CONVECTION BUT MODEL TRENDS CONTINUE LOWER. FOLLOWING THIS EVENT...PATTERN DOMINATED BY UPPER RIDGING OVER THE GULF OF MEXICO AND AFTER WED...SW FLOW ALOFT. SUFFICIENT MOISTURE IN PLACE FOR SCATTERED CONVECTION EACH AFTERNOON AND EVENING AND JUST ENOUGH FLOW ALOFT TO KEEP THINGS INTERESTING. INGREDIENTS DO NOT APPEAR ENOUGH TO SEE MANY SEVERE STORMS BUT ENOUGH TO WORTH MENTIONING. BY LATE WEEK...12Z GFS/GEM/ECMWF DIVERGE A LITTLE ON PROGRESSION OF LARGE UPPER TROUGH OVER WESTERN CONUS WITH GFS/GEM MORE PROGRESSIVE THAN THE EC...THUS MORE FAVORABLE FOR SEVERE STORMS THE WEEKEND FOLLOWING. ALAS THAT IS QUITE A WAY OUT...THE WAY WE LIKE SVR STORMS TO BE AS WELL...FAR AWAY. SNELSON PREVIOUS LONG TERM DISCUSSION /SATURDAY NIGHT THROUGH THURSDAY/... /ISSUED AT 345 AM EDT FRI APR 3 2015/ DRY SATURDAY NIGHT EXPECTED WITH INCREASING MOISTURE AND CLOUDS FOR SUNDAY AS A SOUTHERLY FLOW DEVELOPS WITH WEAKENING SURFACE HIGH PRESSURE. REST OF THE EXTENDED INDICATING A WSW FLOW ALOFT WITH A MOIST SOUTHERLY LOW LEVEL FLOW. FORECAST INSTABILITY BEGINS TO INCREASE MONDAY AND INCREASES FOR TUESDAY THROUGH THURSDAY WITH STORMS TENDING TO HAVE A DIURNAL NATURE. TEMPERATURES WARMING AS WELL DURING THIS PERIOD. THE HIGHEST POPS WILL FAVOR N GA. FORECAST TEMPERATURES STARTING BELOW NORMAL THEN TRENDING ABOVE NORMAL ESPECIALLY AFTER MONDAY. BDL AVIATION.. 00Z UPDATE... /ISSUED 804 PM EDT FRI APR 3 2015/ EVERYTHING LOOKS ON TRACK THIS EVENING FOR DEVELOPING THUNDERSTORMS ACROSS THE ATL AIRFIELDS FIRST AT 05Z AND THEN AFFECTING MCN AND CSG A FEW HOURS LATER. GUIDANCE HAS BEEN TRENDING DOWNWARD FOR CIGS SHOWING SOME IFR POTENTIAL AS FRONT PASSES THROUGH. NOT CONVINCED ON THIS ASPECT YET AS UPSTREAM CONDITIONS HAVE BEEN MOSTLY VFR. WILL CONTINUE CURRENT MVFR FORECAST BUT MONITOR CLOSELY FOR NEEDED CHANGES. BECOMING WINDY ON SAT WITH CURRENT TAF HANDLING THIS WELL WITH GUSTS TO 25 KNOTS LIKELY. //ATL CONFIDENCE...00Z UPDATE... MEDIUM ON IFR POTENTIAL. HIGH ON REMAINING ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 55 68 39 68 / 60 10 0 5 ATLANTA 51 65 41 67 / 70 10 0 5 BLAIRSVILLE 45 60 33 61 / 70 10 0 0 CARTERSVILLE 50 63 38 66 / 70 10 0 0 COLUMBUS 58 70 43 70 / 60 10 0 5 GAINESVILLE 51 63 39 64 / 70 10 0 0 MACON 59 71 40 70 / 60 30 0 5 ROME 49 63 36 66 / 80 5 0 0 PEACHTREE CITY 53 67 38 68 / 70 10 0 5 VIDALIA 63 75 44 71 / 40 40 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... SEVERE THUNDERSTORM WATCH UNTIL 1 AM EDT SATURDAY FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE... DADE...DAWSON...FANNIN...FLOYD...FORSYTH...GILMER...GORDON... LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WALKER...WHITE... WHITFIELD. && $$ SHORT TERM...DEESE LONG TERM....31 AVIATION...DEESE