FXUS63 KIND 292046
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
346 PM EST SUN NOV 29 2009

.DISCUSSION...
SKIES HAVE BECOME MOSTLY CLOUDY ACROSS INDIANA AS A COLD FRONT
MOVES INTO THE AREA. THE FRONT IS CURRENTLY STRETCHING FROM LAKE
MICHIGAN...THROUGH ILLINOIS...AND INTO TEXAS. RAINFALL AND A FEW
EMBEDDED THUNDERSTORMS HAVE BEEN MOVING THROUGH NORTHEAST
ILLINOIS...SOUTHEAST WI...AND LOWER MICHIGAN ALL AFTERNOON. CLOSER
TO HOME...LIGHT RAIN AND DRIZZLE ARE FALLING ACROSS THE FORECAST
AREA AT THIS TIME.   

THE FORECAST FOCUSES ON THE COLD FRONT/RAIN TODAY AND SNOW ON
WEDNESDAY AND THURSDAY.

THIS EVENING AND TONIGHT...RAIN WILL GRADUALLY MOVE ACROSS INDIANA 
FROM NORTHWEST TO SOUTHEAST. THE BEST ISENTROPIC LIFT IS BETWEEN
MON 06 AND 09Z...AND THEN DRY AIR WILL QUICKLY FILTER IN BY
TOMORROW MORNING. THE DRY CONDITIONS WILL LAST THROUGH TUESDAY
NIGHT. TEMPERATURES WILL BE A BIT COOLER TOMORROW...BUT THEY WILL
WARM UP AGAIN BRIEFLY ON TUESDAY. MODELS WERE IN GOOD AGREEMENT
THROUGH TUESDAY NIGHT. SO...WENT WITH A BLEND...BUT LEANED TOWARD
THE HIGHER SIDE OF GUIDANCE. H850 TEMPS ARE AS HIGH AS 5 C THROUGH
THE BEGINNING OF THE WEEK.

IN THE EXTENDED...THE MAIN FOCUS CONTINUES TO BE THE MID WEEK
SYSTEM. MODELS HAVE COME INTO BETTER AGREEMENT...BUT THE GFS
CONTINUES TO BE THE OUTLIER...DRAGGING THE SYSTEM FURTHER SOUTH.
HOWEVER...LATEST MODEL RUNS OF THE GFS HAVE IT COMING INTO
AGREEMENT WITH THE CANADIAN AND ECMWF FOR A BRIEF TIME. THE GFS
THEN SPEEDS UP AND EXITS THE REGION FASTER THAN THE OTHER MODELS.

CONFIDENCE IN PRECIPITATION TYPE IS HIGHER WITH FORECAST SOUNDINGS 
SHOWING TEMPERATURES BELOW FREEZING FROM WEDNESDAY NIGHT THROUGH THE 
DURATION OF EVENT.  RAIN COULD START MOVING INTO THE SOUTHERN 
PORTIONS OF FORECAST AREA AS EARLY AS WED 12Z...BUT RAIN DOESN/T 
REALLY GET GOING UNTIL WED 18Z.  RAIN SHOULD START TRANSITIONING TO 
A RAIN/SNOW MIXTURE BY THU 00Z...AND THEN ALL SNOW AFTER THU 06Z.  
THE BULK OF THE PRECIPITATION SHOULD BE DONE LATE THURSDAY MORNING.  
HOWEVER...THE ECMWF AND GFS WANT TO BRING MOISTURE INTO THE NORTHERN 
FORECAST AREA FROM A SYSTEM OVER THE GREAT LAKES REGION.  THE 
CANADIAN IS THE OUTLIER IN THIS CASE...DECIDED TO LEAVE FLURRIES IN 
THE FORECAST THROUGH FRIDAY MORNING.  TOTAL SNOW ACCUMULATIONS...IF 
ANY...WILL BE AROUND AN INCH.

AS FAR AS TEMPERATURES...STUCK CLOSE GUIDANCE...LOWS IN THE 20S AND 
HIGHS IN THE MID TO UPPER 30S FOR DAYS 4 THROUGH 7.

FURTHER OUT...THE NEXT TROUGH SHOULD START MOVING IN SATURDAY 
NIGHT...BUT MODELS ARE IN NO AGREEMENT AT THIS TIME.

&&

.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.

&&

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

&&

$$

PUBLIC...TDUD
AVIATION...JP