FXUS62 KFFC 120323
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1023 PM EST FRI DEC 11 2009
.UPDATE...
QUICK UPDATE TO TWEAK GRIDS TONIGHT AND EARLY SATURDAY. PUSHED
MEASURABLE PRECIP/WX TO AFTER MIDNIGHT WITH SLT CHC RAIN AND
SLEET. AS PRECIP SPREADS NORTH SATURDAY MORNING...SHOWED MIX OF
RAIN WITH SLEET AS DRY LAYERS COOL THROUGH EVAPORTAIONAL COOLING.
PREVIOUS EXPERIENCE HAS SHOWN THAT LIQUID PRECIP COMING OUT OF
WARM LAYER TENDS TO HAVE LOWER FALL SPPEEDS AND EVAPORATE EASIER
THAN ICE PELLETS IN LOWEST 2000 FT WITH THIS MUCH DRY AIR IN LOW
LEVELS. AFTER 16Z...EXPECT MOST PRECIP TO BE LIQUID AS WARM
ADVECTION AND LATENT HEAT OF FREEZING FROM RAIN CHANGING TO SLEET
WARMS COLUMN. MODIFIED TEMPS/DEWPOINTS BASED ON LATEST OBS AND
SHORT TERM 18Z GUIDANCE TRENDS.
18Z AND 00Z NAM STILL INDICATE POSSIBLITY OF HEAVY RAIN SAT
AFTERNOON AND EVENING. ONLY NEED LESS THAN 1.50 INCHES AT COLUMBUS
TO BREAK ALL TIME ANNUAL RAINFALL RECORD. HARD TO BELIEVE.
SNELSON
&&
.PREV DISCUSSION... /ISSUED 530 PM EST FRI DEC 11 2009/
SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
LATEST SURFACE MAP SHOWS THE COLD DOME OF HIGH PRESSURE CENTERED
OVER KY/TN AND SLOWLY DRIFTING EASTWARD. MODELS CONTINUE TO SHOW A
DISTURBANCE KICKING OUT OF THE WESTERN GULF AND SPREADING OVERRUNNING
RAINS ACROSS THE AREA BEGINNING LATE TONIGHT AND CONTINUING THROUGH
SUNDAY. MAY SEE A FEW SPRINKLES OF RAIN AND/OR SLEET THIS EVENING
OVER THE SOUTHERN THIRD OF THE FORECAST AREA AS CLOUDS THICKEN IN
THE MID LEVELS...BUT NOTHING SHOULD MEASURE...SO WILL HOLD OFF WITH
THE HIGHER POPS UNTIL AFTER MIDNIGHT. TIMING IS STILL A
CONCERN...BUT AT THIS TIME...ALL MODELS HOLD OFF SPREADING RAIN OVER
THE NORTHERN HALF OF THE FORECAST AREA UNTIL AFTER THE COLD LOWS WARM
ABOVE FREEZING. HOWEVER...STILL COULD SEE A FEW SPITS OF SLEET
STARTING OUT IN THE MORNING...BUT TEMPS WARM RATHER QUICKLY...SO NOT
EXPECTING ACCUMULATIONS OR TRAVELING ISSUES. MAIN CONCERN IS THE
POTENTIAL FOR ANOTHER ROUND OF HEAVY RAIN. MODELS ARE ALL OVER THE
PLACE WITH THE PRECIP...WITH NAM SHOWING THE GREATER RAINFALL
AMOUNTS COMING IN ACROSS NORTH GA... ECMWF ACROSS THE CENTRAL
PORTIONS OF THE FORECAST AREA...AND GFS TARGETING MAINLY THE
SOUTHERN THIRD OF THE FORECAST AREA. EITHER WAY...IT APPEARS THE
WHOLE AREA WILL SEE FROM 1 TO 3 INCHES...JUST NOT CONFIDENT YET
WHERE THE 3 INCHES WILL FALL. WITH GROUNDS STILL SATURATED AND
RIVERS AND STREAMS NEAR OR ABOVE BANK-FULL... WILL PLAY IT SAFE AND
ISSUE A FLOOD WATCH FROM 1 PM SATURDAY THROUGH 7 PM SUNDAY FOR THE
ENTIRE FORECAST AREA. EXPECT THE HEAVIER RAINS TO PUSH EAST BY
SUNDAY EVENING. OVERNIGHT LOWS ARE A BIT TRICKY AS CLOUDS HAVE
ALREADY THICKENED...SO NOT SURE TEMPS WILL FALL AS COLD AS GUIDANCE
IS INDICATING. SO WILL LEAN TOWARD THE WARMER NUMBERS FOR TONIGHT.
WITH COOL RAINS AND CLOUDS IN PLACE THROUGH SUNDAY NIGHT...HAVE
STAYED CLOSE TO THE WARMER LOWS AND COOLER HIGHS THROUGH THE SHORT
TERM.
LONG TERM /MONDAY THROUGH FRIDAY/...
MADE LITTLE CHANGES TO THE EXTENDED AS MOISTURE AND RAINS RETURN
QUICKLY ON MONDAY...THEN CONTINUE THROUGH TUESDAY AHEAD OF A COLD
FRONT THAT PUSHES ACROSS THE AREA LATE ON TUESDAY. STILL LOOKS LIKE
HIGH PRESSURE AND DRY CONDITIONS PREVAIL FOR WEDNESDAY-FRIDAY.
FIRE WEATHER...
RED FLAG WARNING WILL BE ALLOWED TO EXPIRE AT 6 PM THIS EVENING.
FUEL MOISTURE'S HAVE FALLEN BELOW 10 GM AS EXPECTED...BUT CLOUDS
MOVED IN A BIT FASTER AND THICKER TODAY AND THIS HAS HINDERED SOME
AREAS REACHING THE CRITICALLY LOW RH BELOW 25 PERCENT AS EXPECTED.
RAINS WILL MOVE IN TONIGHT AND CONTINUE OVER THE WEEKEND.
AVIATION...
HIGH PRESSURE BUILDING EASTWARD INTO THE MID ATLANTIC STATES
OVERNIGHT. CEILINGS REMAINING ABOVE 5 THSD FT UNTIL AFTER 12Z
SATURDAY...THEN LOWERING DURING THE DAY TO IFR IN RAIN AROUND 18Z.
WINDS EAST TO NORTHEAST 5 TO 10KT OVERNIGHT...INCREASING TO 10 TO
15KT AFTER 12Z AS WEDGE STRENGTHENS. VISIBILITY UNRESTRICTED
OVERNIGHT. SPRINKLES OF RAIN OR SLEET POSSIBLE ACROSS CENTRAL GA
TONIGHT... OTHERWISE RAIN DEVELOPING AND SPREADING OVER NORTH AND
CENTRAL GA AFTER 12Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 27 43 37 47 40 / 10 90 100 70 10
ATLANTA 31 43 39 50 47 / 10 100 100 60 10
BLAIRSVILLE 22 40 34 53 37 / 0 70 100 70 10
CARTERSVILLE 27 45 38 48 42 / 10 90 100 60 10
COLUMBUS 35 43 43 57 50 / 20 100 100 70 20
GAINESVILLE 26 40 35 47 43 / 10 90 100 70 10
MACON 33 45 44 56 49 / 10 100 100 70 10
ROME 26 42 40 50 38 / 10 90 100 60 10
PEACHTREE CITY 29 44 43 53 39 / 10 100 100 60 10
VIDALIA 34 48 45 62 54 / 10 100 100 70 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY EVENING FOR
THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...
BLECKLEY...BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...
CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...
CRAWFORD...CRISP...DADE...DAWSON...DEKALB...DODGE...DOOLY...
DOUGLAS...EMANUEL...FANNIN...FAYETTE...FLOYD...FORSYTH...
GILMER...GLASCOCK...GORDON...GREENE...GWINNETT...HALL...
HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON...
JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR...
LAURENS...LUMPKIN...MACON...MADISON...MARION...MERIWETHER...
MONROE...MONTGOMERY...MORGAN...MURRAY...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...TOWNS...TREUTLEN...
TROUP...TWIGGS...UNION...UPSON...WALKER...WALTON...WARREN...
WASHINGTON...WEBSTER...WHEELER...WHITE...WHITFIELD...WILCOX...
WILKES...WILKINSON.
&&
$$
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