FXUS62 KFFC 011750 AAB
AFDFFC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1245 PM EST TUE DEC 1 2009
.UPDATE...
12Z MODELS CONTINUE TO SHOW IMPRESSIVE SYSTEM MOVING THROUGH WED.
GFS A LITTLE FASTER THAN NAM AND ECMWF. UPDATED FCST GRIDS TO TWEAK
HVY RAIN AND TSRA POTENTIAL. UPDATED QPF BASED AT 12Z HPC GUIDANCE.
ALSO BUMPED WINDS UP FOR LATE TONIGHT AND WEDNESDAY AS PREV GFS
GUIDANCE SEEMS TO HAVE UNDERDONE WIND SPEEDS. COULD SEE NEAR HIGH
WIND WARNING CRITERIA IN HIGHER ELEVATIONS WITH LLJ OF 70-80KT
PROGGED BY 12Z GFS AND NAM. FLOOD WATCH LIKELY TO BE ISSUED THIS
AFTERNOON WITH GREATEST THREAT OVER ALL BUT FAR NW ZONES.
SNELSON
&&
.SHORT TERM /TODAY THROUGH THURSDAY/...
MODELS CONTINUE TO ADVERTISE HEAVY RAIN ON WEDNESDAY AS A GULF LOW
PUSHES INTO SOUTH ALABAMA EARLY WEDNESDAY MORNING...THEN TRACKS
ACROSS THE TENNESSEE VALLEY THROUGH WEDNESDAY AFTERNOON. IT APPEARS
THE EVENT WILL START OUT AS A STABLE RAIN TUESDAY NIGHT AS GULF
MOISTURE OVERRUNS A COOL NE WIND FLOW AT THE SURFACE. THEN AS THE
GULF LOW PUSHES NEWD ACROSS ALABAMA AND INTO TENNESSEE...EXPECT A
WARM FRONT TO SURGE NORTHWARD...WITH INCREASING INSTABILITY IN ITS
WAKE. DESPITE CLOUDS AND RAIN...EXPECT MOST UNSTABLE CAPE ACROSS
PARTS OF CENTRAL GEORGIA TO CLIMB INTO THE 200-500 RANGE BY
WEDNESDAY AFTERNOON. ALTHOUGH CAPE VALUES SEEM LOW...EXPECT
FAVORABLE LARGE- SCALE ASCENT AND HIGH SHEAR ENVIRONMENT TO SUPPORT
ON- GOING STORM DEVELOPMENT TO THE SOUTH...THAT SHOULD QUICKLY TRACK
NORTHWARD INTO THE SOUTHERN REACHES OF THE FORECAST AREA. FAST MOVING
ORGANIZED BANDS OF HEAVY SHOWERS OR THUNDERSTORMS COULD PRODUCE
STRONG TO DAMAGING WINDS. THE STRONG LOW LEVEL WIND SHEAR AND HIGH
HELICITY VALUES ALSO SUGGEST A POTENTIAL FOR A FEW SMALL TORNADOES.
IT APPEARS THE MAIN SEVERE THREAT WILL BE FROM LATE WEDNESDAY MORNING
THROUGH WEDNESDAY AFTERNOON... AND GENERALLY ALONG AND SOUTH OF A
WEST POINT TO ATHENS LINE WHERE THE GREATER INSTABILITIES ARE
EXPECTED. ALTHOUGH CONFIDENCE FOR SEVERE STORMS IS FAIRLY LOW...THE
CONFIDENCE FOR HEAVY RAIN IS MUCH HIGHER. STILL EXPECTING WIDESPREAD
RAINFALL AMOUNTS OF 2 TO 3 INCHES WITH SOME ISOLATED HIGHER AMOUNTS
POSSIBLE. THESE AMOUNTS SHOULD BE SUFFICIENT TO CAUSE MINOR FLOODING
OF CREEKS AND RIVERS. WILL UPDATE THE HYDROLOGIC OUTLOOK (ESFFFC)
PRODUCT THIS MORNING...AND SUGGEST THE DAY SHIFT FOLLOW WITH A FLASH
FLOOD WATCH LATER TODAY. THE SYSTEM LIFTS OUT WEDNESDAY NIGHT...BUT
COULD SEE SOME WRAP AROUND CLOUDS PRODUCE PATCHES OF LIGHT RAIN
ACROSS NORTH GA BY THURSDAY MORNING. HOWEVER... TEMPS DO NOT APPEAR
TO BE COLD ENOUGH TO SUPPORT ANY WINTRY MIX. BUILDING HIGH PRESSURE
AND CLEARING CONDITIONS ARE EXPECTED ON THURSDAY.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODELS SHOW SOME SIGNIFICANT CHANGES TO THE EXTENDED THIS RUN. THE
GFS IS DEVELOPING ANOTHER GULF LOW THAT TRACKS ACROSS CENTRAL FLORIDA
ON SATURDAY. THIS WOULD SPREAD AMPLE CLOUDS AND RAIN CHANCES
NORTHWARD INTO GA OVER THE WEEKEND. HOWEVER...PREFER THE ECMWF THAT
DEVELOPS THE SURFACE LOW OFF THE GA/SC COASTS AND TRACKS IT UP THE
ATLANTIC COAST... RESULTING IN MUCH LESS IMPACT HERE OVER THE
WEEKEND. HOWEVER...THE STRONG UPPER DISTURBANCE THAT TRACKS ACROSS
THE DEEP SOUTH AND DEVELOPS THE SURFACE LOW WILL WARRANT A SLIGHT
CHANCE OF RAIN FRIDAY NIGHT AND SATURDAY. ALTHOUGH GUIDANCE HAS
WARMED FRIDAY NIGHT LOWS FOR MOST AREAS... THE NORTHERN THIRD OF THE
STATE REMAINS COLD ENOUGH TO SUPPORT SNOW IF ADEQUATE MOISTURE CAN BE
POOLED AHEAD OF THE APPROACHING DISTURBANCE. HOWEVER...SUSPECT
MOISTURE WILL BE TOO LIMITED TO SEE ANYTHING BUT A FEW FLURRIES OR
SPRINKLES. OTHERWISE...EXPECT COOL HIGH PRESSURE TO PREVAIL
SUNDAY-MONDAY WITH INCREASING RAIN CHANCES BY MID WEEK AS ANOTHER
FRONTAL SYSTEM BEGINS TO KICK EAST OF THE PLAINS.
&&
.AVIATION...
GENERALLY CLEAR SKIES AND LIGHT WINDS HAVE PREVAILED OVERNIGHT...AND
WITH WINDS LIGHTER THAN EXPECTED...VSBYS COULD DROP TO MVFR IN SOME
AREAS. NW WINDS EXPECTED TO SHIFT TO NE AROUND 12Z...AND BECOME EAST
BY 18Z. VFR CONDITIONS ARE EXPECTED TO CONTINUE TODAY...WITH CLOUDS
MOVING IN TONIGHT ASSOCIATED WITH LOW PRESSURE SYSTEM. WINDS WILL
PICK UP LATER TODAY AND OVERNIGHT AS THE SYSTEM APPROACHES...WITH
SOME AREAS SEEING 25KT OR HIGHER GUSTS AFTER 06Z. RAIN WILL BE
MOVING IN LATE TONIGHT...WITH SHOWERS EXPECTED IN THE ATLANTA AREA
BY 06Z. MVFR CIGS EXPECTED EARLY WED. CONVECTIVE ACTIVITY EXPECTED
ACROSS PORTIONS OF CENTRAL GA WED...BUT HAVE HELD OFF INTRODUCING
CB/TS IN CSG AND MCN TAFS FOR NOW.
31/LEG
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 59 44 52 45 58 / 0 90 100 50 10
ATLANTA 57 44 56 42 54 / 5 100 100 40 10
BLAIRSVILLE 56 39 51 39 51 / 0 80 100 60 10
CARTERSVILLE 58 43 55 41 54 / 0 90 100 50 10
COLUMBUS 60 51 65 45 61 / 10 100 100 20 10
GAINESVILLE 56 43 50 43 54 / 0 90 100 50 10
MACON 62 51 64 45 62 / 10 100 100 40 10
ROME 58 44 54 42 53 / 0 90 100 50 10
PEACHTREE CITY 58 46 61 41 55 / 5 100 100 30 10
VIDALIA 65 51 68 47 62 / 0 90 100 60 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
39/31
