FXUS63 KIND 142237
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
535 PM EST MON DEC 14 2009

.AVIATION...DISCUSSION FOR 150000Z TAF ISSUANCE. APPEARS SURFACE 
COLD FRONT IS CURRENTLY LOCATED ACROSS THE NORTHWESTERN ZONES...WITH 
MODEL DATA INDICATING IT SHOULD BE EAST OF THE TERMINALS BY OR 
SHORTLY AFTER ISSUANCE TIME. WIND SHIFT WITH COLD FRONT NOT VERY 
SHARP...BUT RATHER A GRADUAL VEERING TO 280-300 HEADINGS. BASED ON 
WHAT IS UPSTREAM...CEILINGS SHOULD SETTLE INTO THE 015-020 RANGE IN 
THE WAKE OF FRONTAL PASSAGE. SOME AREAS OF IFR CEILINGS 007-009 ABOVE 
GROUND LEVEL ALSO NOTED IN THE POST FRONTAL ZONE...SO EXPECTING SOME 
TEMPORARY IFR CEILINGS TO AFFECT MAINLY KLAF/KIND/KHUF THROUGH ABOUT 
150600Z.

SOME SURFACE WIND GUSTS 20-25KTS FROM 280-300 HEADINGS PROBABLE 
ACROSS THE TERMINALS THIS EVENING BASED ON UPSTREAM OBSERVATIONS. 
PRESSURE GRADIENT SHOULD SLACKEN A BIT LATER TONIGHT...SO GUSTS 
EXPECTED TO DIMINISH TOWARDS OR AFTER 150600Z.

&&

.DISCUSSION...ACROSS THE FORECAST AREA THIS AFTERNOON...TEMPERATURES 
REBOUNDED NICELY INTO THE 50S AS THE INVERSION SHALLOWED OUT 
SUBSTANTIALLY AND ALLOWED SOME CLEARING TO OCCUR AHEAD OF THE 
FRONTAL BOUNDARY CURRENTLY STRETCHING FROM NEAR GARY TO DECATUR IL 
AND ST LOUIS. DEWPOINTS WERE IN THE LOW TO MID 40S...WITH BREEZY 
CONDITIONS OUT OF THE SOUTHWEST. AN ABRUPT CHANGE BACK TO COLD 
CONDITIONS IS IN THE OFFING AS THE AFOREMENTIONED COLD FRONT PUSHES 
QUICKLY THROUGH THE AREA THIS EVENING.

FORECAST FOCUS OF THE DAY WILL GENERALLY BE TEMPERATURES...AS 
PRECIPITATION APPEARS UNLIKELY.

MODELS WERE IN A DECENT STATE OF AGREEMENT AND A BLEND WAS USED 
TODAY. THE FRONT WILL BLAST THROUGH THE AREA THIS EVENING...REACHING 
OUR NORTHWEST CORNER IN THE NEXT COUPLE OF HOURS...THROUGH IND 
AROUND 01Z...AND EXITING OUR SOUTHEAST BEFORE MIDNIGHT. LOW LEVEL 
MOISTURE HAS FAILED TO PRODUCE ANY DRIZZLE TODAY...AND UPSTREAM OBS 
INDICATE LITTLE TO NO PRECIPITATION OCCURRING. ISENTROPIC SURFACES 
SHOW STRONG DOWNGLIDE AFTER FRONTAL PASSAGE TONIGHT AND COLUMN GETS 
DRIER AND DRIER...SO HAVE REMOVED ALL WEATHER FROM GRIDS. MAIN 
IMPACT OF THE BOUNDARY WILL BE RETURN TO LOW OVERCAST SKIES AND 
QUICK COOLING.

REMAINDER OF THE SHORT TERM...AND INDEED MOST OF THE FORECAST 
PERIOD...IS DRY AS THE ARCTIC HIGH SETTLES INTO THE CENTRAL PART OF 
THE NATION AND SLOWLY PUSHES EASTWARD BEFORE RETREATING NORTHWARD 
LATE IN THE WEEK.

ON TEMPERATURES...MAV LOOKS GOOD THROUGHOUT THE SHORT TERM...AS IT 
DEPICTS GOOD LOW LEVEL COOLING OCCURRING...BUT BULK OF COLDEST AIR 
IS NOT LIKELY TO ARRIVE BY END OF THE OVERNIGHT PERIOD...AND DEPICTS 
WARMING TOMORROW AS CLEARING IS LIKELY TO BEGIN IN THE DAY...AND 
THAT SHOULD ALLOW US TO RECOVER TO LEVELS ABOVE MET DEPICTIONS...AND 
UPSTREAM TEMPS FIT WELL WITH THIS. TOMORROW NIGHT...MAV FITS WELL 
WITH EXPECTED 850 TEMPERATURES...AND COOLER MET IS UNLIKELY AS WEAK 
WARM ADVECTION BEGINS IN EARNEST OVERNIGHT. FOR WEDNESDAY...WEAK 
WARM ADVECTION CONTINUES...BUT THE OPERATIONAL MAV IS THE HIGHEST 
END OF THE ENSEMBLES AND THIS SEEMS UNLIKELY...SO USED A MIX OF THE 
OPERATIONAL AND ENSEMBLE AVERAGES.

&&

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

&&

$$

PUBLIC...NIELD
AVIATION...JAS