FXUS62 KFFC 081000
AFDFFC
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
500 AM EST TUE DEC 8 2009
.SHORT TERM /TODAY THROUGH THURSDAY/...
A POWERFUL PACIFIC SYSTEM CROSSING THE SOUTHERN/CENTRAL ROCKIES
THIS MORNING WILL CROSS THE CONTINENTAL DIVIDE TODAY...WITH LEE
CYCLOGENESIS RESULTING IN A DEEPENING SURFACE LOW TRACKING FROM
OKLAHOMA TO MICHIGAN BY WEDNESDAY. A FRONTAL BOUNDARY ARCING FROM
THE TEXAS GULF COAST TO FLORIDA WILL BEGIN SURGING NORTHWARD
TODAY IN RESPONSE TO THIS STRENGTHENING CENTRAL U.S. LOW PRESSURE
SYSTEM. A 1025 MB HIGH CONTINUES TO NOSE INTO GEORGIA FROM THE
NORTHEAST CURRENTLY...WITH THE WEDGE BECOMING MORE FIRMLY
ENTRENCHED THIS MORNING. THIS IS BEST ILLUSTRATED BY THE EARLY
MORNING SURFACE TEMPERATURES IN THE UPPER 30S FROM AHN-PDK WITH
WARMER 40S AND 50S TO THE WEST AND SOUTH.
TEMPERATURES WILL HOLD STEADY IN AREAS THAT ARE SOLIDLY UNDER THE
WEDGE TODAY AS WIDESPREAD RAIN DEVELOPS DUE TO INCREASING
ISENTROPIC ASCENT AND APPROACHING RIGHT EXIT REGION OF 170 KT H2
JET STREAK. TEMPS STILL STEADY OR RISING TONIGHT AS 70 KT SSW LLJ
AXIS CROSSES GEORGIA...FORCING THE RETREAT OF THE WEDGE OUT OF ALL
BUT POSSIBLY NORTHEAST GA AND BRINGING STRONG SOUTH WINDS TO THE
NORTH GA MOUNTAINS. MOST OF OUR FORECAST AREA SHOULD BE IN/NEAR
THE WARM SECTOR BY LATE TONIGHT WITH MODELS SUGGESTING LIMITED BUT
SUFFICIENT INSTABILITY (CAPES GENERALLY 200-800 J/KG) FOR A FEW
SEVERE STORMS TONIGHT. WIND AND ISOLATED TORNADO RISK IS OUR
GREATEST CONCERN GIVEN VERY STRONG DEEP LAYER AND LOW LEVEL SHEAR.
HEAVY RAIN POTENTIAL STILL EXISTS...BUT NOT QUITE ENOUGH TO TIP
THE SCALES IN FAVOR OF A FLOOD WATCH AS RAIN LOOKS TO BE MODERATE
AND OVER A LONG ENOUGH TIME PERIOD TO PREVENT WIDESPREAD
PROBLEMS...WITH 1-3 INCH RAINFALL AMOUNTS POSSIBLE ESPECIALLY
NORTH.
INSTABILITY AXIS SHIFTS INTO CENTRAL GA WEDNESDAY MORNING WITH
COLD FRONT CLEARING EAST CENTRAL GA BY ~21Z. HIGH PRESSURE
BUILDING IN QUICKLY FROM THE WEST WITH TIGHT PRESSURE GRADIENT
KEEPING WINDS STIFF THROUGH LATE WEDNESDAY. IN FACT...LATER SHIFTS
WILL LIKELY NEED TO EXPAND WIND ADVISORY INTO THE REST OF NORTH GA
FOR WEDNESDAY. THE HIGH CENTER WILL PASS NEAR TO OUR NORTH ON
THURSDAY...BRINGING LESSENING WINDS AND CLEAR SKIES.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
RETURN FLOW ON THE BACKSIDE OF THE HIGH WILL ALLOW MOISTURE BACK
INTO THE SOUTHEASTERN STATES ON FRIDAY AHEAD OF A GULF COASTAL
LOW. EXACT TIMING OF THIS SATURDAY LOW PRESSURE SYSTEM AND ANOTHER
PASSING THROUGH ON MONDAY ARE HANDLED SOMEWHAT DIFFERENTLY BY THE
GLOBAL MODELS/ENSEMBLES AS ONE WOULD EXPECT WITH THIS FAST AND
PROGRESSIVE ZONAL UPPER LEVEL PATTERN...SO TRIED TO BLEND THE
DIFFERENCES AND LEANED TOWARD A CONSENSUS FORECAST SOLUTION IN THE
EXTENDED. THERMAL FIELDS ARE CLOSER TOGETHER THAN LAST NIGHTS
MODELS IN THE EXTENDED...TRENDING TOWARD THE WARMER ECMWF. THIS
WOULD KEEP THE P-TYPE LIQUID FOR US AS H8 TEMPS LOOK TO BE FAIRLY
WELL ABOVE FREEZING.
RRH
&&
.AVIATION...
LOW CEILINGS OVER THE AREA WITH LIGHT RAIN MOVING IN FROM THE WEST.
WITH THE WEDGE BUILDING IN FROM THE NE WE WILL KEEP EASTERLY WINDS
AT THE SURFACE. WINDS CURRENTLY IN THE 2-6KT RANGE ACROSS THE STATE
BUT WILL SEE WINDS SPEED INCREASE INTO THE 10-15KT RANGE WITH HIGHER
GUST BY 15Z-18Z. THESE LOW CEILINGS SHOULD STAY IN ACROSS THE AREA
THROUGH THE TAF PERIOD. THE RAIN SHOULD BEGIN IN THE ATL AREA BY
12Z-14Z WITH TSRA MOVING IN AFTER 00Z WED. VSBYS WILL BE IN THE IFR
TO MVFR RANGE DURING THE DAY WITH LIFR TO VLIFR CONDITIONS EXPECTED
AFTER 00Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 44 43 62 36 52 / 100 100 50 10 5
ATLANTA 52 48 65 33 50 / 100 100 40 10 5
BLAIRSVILLE 46 44 54 25 42 / 100 100 40 10 10
CARTERSVILLE 48 48 60 29 47 / 100 100 40 10 5
COLUMBUS 57 55 72 39 55 / 90 100 50 10 5
GAINESVILLE 42 41 58 33 50 / 100 100 50 10 5
MACON 55 55 71 39 56 / 90 90 60 10 5
ROME 52 47 58 31 48 / 100 100 20 10 10
PEACHTREE CITY 54 49 64 32 51 / 100 100 40 10 5
VIDALIA 60 57 77 44 58 / 80 50 60 10 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 6 PM EST WEDNESDAY FOR
THE FOLLOWING ZONES: CHATTOOGA...DADE...DAWSON...FANNIN...
GILMER...LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WALKER...
WHITE.
&&
$$
