FXUS62 KFFC 230239 AAA
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
539 PM EST TUE DEC 22 2009
.UPDATE...
DID A QUICK UPDATE TO FORECAST PACKAGE TO INCREASE CLOUDS AND WARM
OVERNIGHT LOWS UP A FEW DEGREES MOST PLACES...ESPECIALLY ACROSS THE
WESTERN HALF OF THE FORECAST AREA. THIS WAS MAINLY DUE TO HIGH
CLOUDS BEGINNING TO SPREAD IN FROM THE WEST AND MID CLOUDS ADVECTING
UP FROM THE SOUTHWEST. LATEST SURFACE OBS SHOW DEWPOINTS IN THE MID
AND UPPER 30S. EXPECT DEWPOINTS TO HAVE TROUBLE FALLING OFF TOWARD
MORNING AS CLOUDS HINDER THE RADIATIONAL PROCESS. OTHERWISE...REST
OF FORECAST LOOKS ON TRACK AT THIS TIME. /39
-------------------PREVIOUS DISCUSSION----------------------
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
SHORT TERM MODELS CONTINUE TO BE IN PRETTY GOOD AGREEMENT THIS RUN.
THERE ARE SOME MINOR DISCREPANCIES BUT THE OVERALL SOLUTIONS ARE
CLOSE. THE UPPER LOW OVER THE PACIFIC NORTHWEST DEEPENS AS IT DIGS
INTO THE DESERT SOUTHWEST THROUGH WEDNESDAY EVENING...THEN LIFTS
INTO THE CENTRAL PLAINS THROUGH THURSDAY NIGHT. THE UPPER FLOW
ACROSS THE SOUTHEAST WILL BECOME MORE SOUTHWEST WITH TIME...
INCREASING MOISTURE ACROSS THE FORECAST AREA. THIS SOLUTION SLOWS
DOWN THE ONSET OF RAINFALL OVER THE SOUTHEAST AS OVERRUNNING SETS UP
THURSDAY. MODELS CONTINUE TO SHOW COLD AIR DAMMING AND WEDGE
SETTING UP ON WEDNESDAY WITH COOLER NORTHEAST AND EAST FLOW ACROSS
THE AREA THROUGH THURSDAY NIGHT. MODELS SHOW STRONG H85 JET ACROSS
THE AREA THURSDAY AFTERNOON AND THURSDAY NIGHT...WITH PERIODS OF
HEAVY RAIN POSSIBLE BEGINNING THURSDAY AFTERNOON. MODEL QPF NOT AS
HIGH AS THE PAST SEVERAL DAYS BUT SEE POTENTIAL FOR 1-2 INCHES WITH
ISOLATED HEAVIER AMOUNTS...AND WILL CONTINUE HYDROLOGIC OUTLOOK FOR
THURSDAY AND THURSDAY NIGHT. WILL KEEP ISOLATED THUNDER IN ACROSS
CENTRAL PORTIONS THURSDAY EVENING AS INSTABILITY MINIMAL. GUIDANCE
TEMPERATURES SHOWING A COOL DOWN OF HIGH TEMPERATURES THROUGH THE
END OF THE WEEK. OVERNIGHT MINS HAVE BEEN RUNNING A WARM THE PAST
COUPLE OF DAYS AND WITH CLEAR SKIES...LIGHT WINDS CONTINUING FIRST
PERIOD WILL UNDERCUT COOLER MAV ONCE AGAIN.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
MODELS QUICKLY PUSH THE FRONT THROUGH THE AREA ON FRIDAY WITH DRIER
AIR ON TAP AS SURFACE HIGH PRESSURE BUILDS IN ACROSS THE AREA. GFS
IS BRINGING ANOTHER SYSTEM ACROSS THE NORTHERN GULF EARLY NEXT
WEEK...HOWEVER THE ECMWF NOT PICKING UP THE SYSTEM AT ALL. LOW
CONFIDENCE THIS FAR OUT AND WILL NOT MAKE ANY CHANGES TO THE
EXTENDED THIS FORECAST.
&&
.AVIATION...
DEWPOINTS CONTINUE TO CREEP UPWARD EACH DAY...WHICH INCREASES THE
CHANCE OF MORNING VSBY ISSUES. DIFFERENCE TONIGHT IS THAT HIGHER
CLOUDS SHOULD REDUCE RADIATIONAL COOLING AND MINIMIZE THE RISK OF
SATURATION. MODELS ARE CONSISTENT IN KEEPING DEWPOINT DEPRESSIONS
OF >2 DEG F FOR THE AREA...SO WILL PUT SOME BR IN THE USUAL
AREAS...MVFR AT BEST. A BIT WORRIED THAT SOME STRATUS MAY SNEAK IN
FROM THE SW BY SUNRISE AS THE THETA-E RIDGE STARTS TO BUILD. WILL
WATCH THAT AND DECIDE AT FCST TIME.
WINDS TAKING THEIR TIME SWITCHING TO SOUTHEASTERLY...BUT SHOULD
BEGIN TO DO SO AS SFC RIDGE SLIDES NORTHEAST. EXPECTING TO SEE THE
SWITCH SOMEWHERE AROUND 00Z OR A BIT LATER. NO LOW CIGS EXPECTED
TONIGHT...AND ONLY SCT250 PERHAPS GOING TO BKN BY LATE MORNING AS
SOUTHERN U.S. SYSTEM APPROACHES.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 33 54 36 48 40 / 0 0 5 60 100
ATLANTA 38 57 39 51 39 / 0 5 5 80 100
BLAIRSVILLE 27 52 31 47 38 / 0 5 5 70 100
CARTERSVILLE 32 53 37 52 42 / 0 5 5 90 100
COLUMBUS 35 60 44 57 46 / 0 10 10 90 100
GAINESVILLE 36 53 36 47 36 / 0 5 5 70 100
MACON 30 61 40 57 47 / 0 5 5 70 100
ROME 30 56 38 56 42 / 0 5 10 90 100
PEACHTREE CITY 32 58 36 52 40 / 0 5 5 90 100
VIDALIA 34 60 40 61 52 / 0 0 5 40 90
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
12/27
