FXUS63 KIND 291631
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1130 AM EST SUN NOV 29 2009

.AVIATION...DISCUSSION FOR THE 18Z TAFS.

COLD FRONT WAS DRAPED ACROSS LOWER MICHIGAN TO CENTRAL ILLINOIS AND 
SOUTHWEST MISSOURI LATE THIS MORNING. RECENT RADAR TRENDS SUGGEST 
RAIN ALONG AND AHEAD OF THE FRONT IS TRYING TO DEVELOP. INFRARED 
PICTURES SHOW ABUNDANT MVFR CLOUD COVER ACROSS THE AREA AND SOME 
MVFR CEILINGS DEVELOPING OVER SOUTHEAST MISSOURI.

GOOD Q VECTOR CONVERGENCE LATE THIS AFTERNOON ACROSS CENTRAL 
INDIANA. FURTHERMORE TIME HEIGHT SECTIONS INDICATE BEST MOISTURE AND 
LIFT AVAILABLE LATE THIS AFTERNOON AND EARLY THIS EVENING. HENCE 
WILL AIM FOR A 4 TO 5 HOUR PERIOD OF MVFR CEILINGS AND VISIBILITIES 
AT THE TAF SITES AS THE FRONT PASSES.

GOOD SUBSIDENCE AND COLD AIR ADVECTION IN THE WAKE OF THE FRONT 
SHOULD END THE RAIN THREAT...BUT FORECAST SOUNDINGS STILL INDICATE 
SATURATED LOWER LEVELS OF THE AIRMASS. THUS WILL KEEP SOME MVFR 
CEILINGS THROUGH THE OVERNIGHT HOURS. A RETURN TO VFR CONDITIONS IS 
EXPECTED BY MONDAY AFTERNOON AS A RIDGE OF HIGH PRESSURE DROPS INTO 
CENTRAL INDIANA FROM THE UPPER MIDWEST.

&&

.UPDATE...
A COLD FRONT IS CONTINUING TO MOVE CLOSER TO INDIANA.
CURRENTLY...IT IS EXTENDING ALONG A LINE FROM LAKE
MICHIGAN...THROUGH NORTHEAST ILLINOIS...AND DOWN INTO THE
SOUTHERN PLAINS. SO FAR...RAIN AND A FEW EMBEDDED 
THUNDERSTORMS HAVE BEEN CONFINED TO SOUTHEAST WI AND NORTHEAST IL.
FORECAST IS ON TRACK WITH RAIN EXPECTED TO MOVE INTO SOUTHERN IN
LATE THIS AFTERNOON. HIGHS SHOULD STILL HAVE ENOUGH TIME TO TOP
OFF IN THE 50S AHEAD OF THE FRONT.

&&

.PREVIOUS DISCUSSION...

FORECAST FOCUS IS ON CHANCES FOR RAIN TODAY AND TONIGHT.

AT 07Z AN UPPER TROF WAS ACROSS THE MINNESOTA AND THE DAKOTAS. A
COLD FRONT WAS AHEAD OF THE FRONT EXTENDED FROM WISCONSIN
SOUTHWEST INTO KANSAS. TEMPERATURES ACROSS OUR AREA REMAIN MILD IN
THE 40S TO AROUND 50.

MODELS ARE IN DECENT AGREEMENT EARLY THIS WEEK AND WILL USE A
BLEND. FOR THE MID WEEK SYSTEM...GFS HAS TAKEN A BIG TURN AND
MOVED THE SYSTEM FAR ENOUGH SOUTH AND EAST THAT IT FORECASTS NO
PRECIPITATION ACROSS OUR AREA. CANADIAN AND ECMWF STILL KEEP
CHANCES FOR PRECIPITATION ACROSS THE AREA. GFS ENSEMBLES SHOW
SEVERAL MEMBERS WITH PRECIPITATION ACROSS THE AREA...SO WILL
IGNORE 00Z GFS AND GO WITH CANADIAN/ECMWF SOLUTIONS HERE.

TODAY...CLOUDS WILL INCREASE DURING THE MORNING AS THE COLD FRONT
APPROACHES AND MOISTURE MOVES NORTH AHEAD OF IT. AS THE AFTERNOON
PROGRESSES...ISENTROPIC LIFT INCREASES AND AN UPPER JET BEGINS TO
PROVIDE DIVERGENCE ALOFT. WITH THE INCREASE IN MOISTURE AND
LIFT...RAIN LOOKS TO BE A GOOD BET ACROSS MOST OF THE AREA BY 00Z.
BOTH MAV/MET HAVE INCREASED THEIR POPS INTO LIKELY OR ABOVE AS
WELL. THUS HAVE WENT LIKELY POPS MOST AREAS...BUT TIMED THEM TO
OCCUR AFTER 21Z. MAV/MET HIGH TEMPERATURES ARE PRETTY CLOSE AND
LOOK REASONABLE WITH THE LATE ARRIVAL OF RAIN AND A MILD START TO
THE DAY.

THE RAIN WILL SHIFT QUICKLY SOUTH AND EAST ACROSS THE AREA DURING
THE EVENING HOURS AS THE FRONT MOVES THROUGH. NORTHWESTERN PARTS
OF OUR AREA WILL ONLY SEE CHANCE POPS...WITH LIKELY OR HIGHER POPS
ACROSS THE SOUTHEAST HALF OF THE AREA WHERE FORCING IS MAXIMZED.
AFTER 06Z ONLY THE FAR SOUTHERN AND EASTERN SECTIONS WILL SEE A
LINGERING CHANCE OF RAIN. COLDER AIR WILL BEGIN TO MOVE IN BEHIND
THE FRONT...AND A BLEND OF THE SIMILAR MAV/MET NUMBERS LOOK GOOD
FOR LOW TEMPERATURES.

HIGH PRESSURE MOVES IN AND PROVIDE DRY YET COOL CONDITIONS FOR
MONDAY. ANOTHER WEAKER SYSTEM IMPACTS THE GREAT LAKES ON MONDAY
NIGHT AND WILL BRING MORE CLOUDS TO NORTHERN AREAS THEN. LOOKS
LIKE FORCING WILL REMAIN TO THE NORTH OF THE AREA...SO HAVE
REMOVED THE CHANCES FOR RAIN ACROSS THE FAR NORTHEAST.

AS MENTIONED EARLIER...STILL A LOT OF UNCERTAINTY WITH THE SYSTEM
FOR MID WEEK. LEFT PREVIOUS FORECAST PRETTY MUCH INTACT AS IT
AGREES WITH THE MODEL BLEND CHOSEN. NOT TOO SURE ABOUT
ACCUMULATING SNOW WEDNESDAY NIGHT AND THURSDAY AT THIS POINT
GIVEN THE UNCERTAINTY. ALSO A WARM GROUND WILL TEND TO HELP
INHIBIT ACCUMULATIONS AT THIS POINT IN A MARGINAL SITUATION. WILL
DOWNPLAY THE MENTION IN THE HWO FOR NOW.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE. 

&&

$$

AVIATION...JP
PUBLIC...CS
UPDATE...TDUD