FXUS63 KIWX 021048
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
548 AM EST WED DEC 2 2009

.AVIATION...
POTENT SYSTEM NEAR THE WESTERN GULF COAST POISED TO LIFT NE TODAY 
BRINGING STEADILY INCREASING CLOUDS AND LOWERING CIGS AS RAIN 
OVERSPREADS THE AREA THIS AFTERNOON...REACHING KFWA EARLY THIS
EVENING. CIG/VIS WILL DROP QUICKLY TO MVFR AND PERSIST OVERNIGHT
WITH PERIODIC IFR CONDITIONS POSSIBLE. RAIN WILL MIX WITH SNOW
AT KSBN BY LATE TONIGHT WHILE INDICATIONS ARE THAT PTYPE MAY
REMAIN RAIN THROUGH MORNING AT KFWA AS LATE AS 06Z MODEL RUN IS YET
WARMER WITH LLEVEL TEMPS THROUGH 12Z THU. EAST WINDS 10-15 KNOTS
BACK THROUGH NORTHWEST BY END OF TAF PD.

&&

.PREV DISCUSSION... /ISSUED 356 AM EST WED DEC 2 2009/ 

SHORT TERM...
WV LOOPS CLEARLY SHOWS THE STAGE IS SET FOR THE LONG ADVERTISED
MID WEEK SYSTEM TO COME TOGETHER OVER THE EASTERN HALF OF THE
COUNTRY. UPPER LOW THAT WAS STUCK OVER THE SOUTHWEST HAS BEEN
KICKED OUT BY SOUTHERN STREAM AND IS MOVING NORTHEAST TROUGH TEXAS
WHILE THE ASSOC SFC LOW IS CENTERED ALONG THE GULF COAST OF
LOUISIANA. NARROW RIDGING BECOMING MORE AMPLIFIED OFF THE PAC NW
COAST AS BROAD COLD TROUGH DIGS SOUTH THROUGH THE CENTRAL PLAINS
WORKING TO FUNNEL COLD AIR MASS SOUTH. AFOREMENTIONED UPPER LOW
WILL BE ABSORBED INTO NE FLOW ON THE SOUTHERN FLANK OF DEEPENING
TROUGH BRINGING ITS ASSOCIATED LLEVEL CIRCULATION AND ITS DEEP
MOISTURE FEED THROUGH THE OHIO VALLEY. RAIN WILL MOVE INTO THE CWA
FROM THE SOUTH DURING THE AFTERNOON AND OVERSPREAD THE CWA DURING
BY EVENING WITH THE QUESTION OF WHEN/WHERE ANY PTYPE TRANSITION
WILL OCCUR OVERNIGHT.

THE MODELS ARE NOW LESS SPREAD REGARDING THE SFC LOW TRACK BUT STILL 
SHOW THE SAME VARIATIONS TO LESSER DEGREE... /THE 00Z GFS FURTHEST EAST 
AND THE NAM AND SREF TO THE WEST/... WHILE H850 LOW POSITIONS ARE
MORE TIGHTLY CLUSTERED NEAR CLEVELAND BY 06Z THU. STILL PREFER THE
MORE WESTERLY TRACK AS DEEPENING SFC LOW LIFTS UNDER A NEGATIVELY
TILTED MID LEVEL WAVE. THIS FAVORS THE WARMER SIDE OF GUIDANCE
WITH 1310M 1000-850 THICKNESSES AND 35C SFC WET BULBS IN PLACE
THROUGH 06Z OVER ALL BUT THE EXTREME NW CWA. NAM BUFR SOUNDINGS
ARE SIMILARLY PESSIMISTIC TOWARDS A CHANGEOVER WITH THE BULK OF
MOISTURE AND DEFORMATION LIFTING TO THE NE WELL AHEAD OF
SUBSTANTIAL CAA. AS SUCH...RAIN AND RASN MIX IS EXTENDED WITH
TRANSITION TO ALL SNOW PUSHED BACK BOTH GEOGRAPHICALLY AND
TEMPORALLY TO 06Z IN THE NW AND 12Z IN THE SE. BY THIS TIME
PRECIPITATION RATES SHOULD BE MILD...AND ANY AREAS THAT MANAGE
ACCUMULATION ARE EXPECTED ONLY TO SEE UP TO AN INCH OR LESS
MOSTLY ON GRASSY SURFACES. IF THE MODELS ARE STILL HOLDING AN
EASTWARD BIAS EVEN THIS MAY YET PROVE TO BE TOO OPTIMISTIC. AS
COLDER AIR OVERSPREADS THE CWA THURSDAY MORNING FLURRIES WILL BE
POSSIBLE THROUGH THE DAY UNDER COLD AND DREARY SKIES.

BY 18Z AS WINDS BACK NW AND SUFFICIENTLY COLD H85 TEMPS ARRIVE LAKE 
EFFECT BEGINS TO KICK IN QUICKLY ON THE HEELS OF DEPARTING SYSTEM 
AND OVERALL REASONING HAS NOT CHANGED MUCH FOR SEVERAL RUNS. A 
PERIOD OF LAKE ENHANCEMENT INTO NORTHERN INDIANA COUNTIES IS 
POSSIBLE AS H95 TEMPS COOL TO -8C BY 18Z THU BUT WINDS BACK STEADILY 
WEST WHILE LAKE INDUCED INSTABILITY INCREASES THURSDAY NIGHT AS 
TEMPS FALL FURTHER GENERATING DELTA TS ON THE ORDER OF 20C BY FRIDAY 
MORNING...BUT WITH SW FETCH TAKING THE BULK OF THE ACTION
FURTHER NORTH INTO CENTRAL MICHIGAN.

LONG TERM...
STG SW TROUGH OVR CNTRL TX THIS AM WILL LIFT RAPIDLY NEWD THROUGH 
THE OH RVR VALLEY AHD OF DIGGING NRN STREAM TROUGH OVR WY SHRT TERM 
AND OFF THE NEW ENGLAND COAST TO START THE LONG TERM. COLD POCKET 
UNDERNEATH NRN STREAM TROUGH WILL ADV EWD W/CORE OF COLDEST AIR XPCD 
FRI/FRI NIGHT. HWVR LL FLW ALIGNMENT IN WAKE OF LEAD SRN STREAM SW 
BACKS RAPIDLY TO THE SW AND W/LOSS OF APPRECIABLE SYNOPTIC SCALE 
MSTR LES POTENTIAL LIMITED. IN FACT DOUBT ANY APPRECIABLE 
ACCUMULATION IS ON TAP EVEN OVR NRN BERRIEN WHERE BTR MSTR/LL FORCING 
COINCIDES LT THU NIGHT/FRI. EVEN THOUGH WILL LEAVE POPS GENERALLY AS 
IS OTHER THEN A SLIGHT NWD BUMP IN PREV N/S GRADIENT. 

OTHERWISE AMPLIFIED PATTN BREAKS DOWN INTO PROGRESSIVE/UNSETTLED 
WESTERLY FLW BY LT WEEKEND AND ULTIMATELY LIKELY TO REAMPLIFY INTO 
NXT WEEK ALTHOUGH MED RANGE MODEL GUIDANCE ALL OVR THE PLACE IN THAT 
REGARD. GGEM HAS PROVEN SUPERIOR LATELY AND ITS SUGGESTION ON DEEP 
PLAINS CYCLOGENESIS MID NXT WEEK ALIGNS WELL W/OP GFS/ENSEMBLE MEAN. 
HWVR TYPHOON NADI OVR THE WPAC WILL UNDERGO A QUICK YET WEAK 
EXTRATROPICAL TRANSITION AHD OF A MID LAT TROUGH COMING OUT OF 
CHINA. HWVR GIVEN THE HIGH MOMENTUM FLW EXISTING DOWNSTREAM THROUGH 
THE NPAC...XPC THIS SYS WILL REGENERATE FURTHER DOWNSTREAM INTO A 
MORE INTENSE BAROCLINIC WAVE AS SEEN IN GFS/GGEM SOLUTIONS AND WHICH 
FVRS THEIR DEEP PLAINS CYCLONE IDEA TWD DY8 GIVEN XPCD CONCURRENT 
HIGH AMPLITUDE WRN RIDGE/PLAINS TROUGH DVLPMNT AT THAT TIME.

TEMPS THROUGH THE PD BLO NORMAL.

AVIATION...
UPPER LOW OVER TEXAS STILL ON TARGET TO MOVE INTO THE REGION ON WEDNESDAY
ALONG WITH ASSOCIATED LLEVEL CIRCULATION BRINGING STEADILY
WORSENING CONDITIONS THROUGH THE DAY. ONSET OF PRECIP IS EXPECTED
DURING THE AFTERNOON AT KFWA MARCHING NORTH TO KSBN AROUND SUNSET.
CIG/VIS WILL FALL TO MVFR OVERNIGHT AND REMAIN RESTRICTED THROUGH
THE REMAINDER OF THE PD. WINDS WILL PICK UP TO 10-15 KNOTS AND
BACK STEADILY TO N/NW BY THURSDAY MORNING. AS COLDER AIR INVADES ON
THE BACK SIDE OF THE SYSTEM...CHANGEOVER TO -SN IS EXPECTED AT
KSBN NEAR THE END OF THE TAF PD WHILE HOLDING OFF AT KFWA UNTIL
AFTER 06Z THU.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SHORT TERM...LUD 
LONG TERM...T
AVIATION...LUD/T