FXUS63 KIND 120446
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1145 PM EST FRI DEC 11 2009

.AVIATION...DISCUSSION FOR 12/06Z TAFS.
VFR CONDITIONS WILL CONTINUE FOR ABOUT THE NEXT 20 HOURS AND THEN 
DROP RAPIDLY TO LOW MVFR OR IFR AS RAIN SPREADS INTO OUR REGION.  

HIGH PRESSURE FROM NORTH CAROLINA TO KENTUCKY WILL CONTINUE TO 
DOMINATE OUR WEATHER AS IT MOVES SLOWLY EASTWARD.  CLEAR SKIES 
SHOULD CONTINUE OVER TAF SITES UNTIL SUNRISE.  BROKEN CLOUDS AROUND 
5 THOUSAND WILL SPREAD INTO THE OHIO VALLEY BY SUNRISE.  BUT MOST 
OF THIS CLOUDINESS SHOULD REMAIN FROM SOUTHERN INDIANA AND SOUTHWARD 
UNTIL MID OR LATE SATURDAY AFTERNOON.  

AN UPPER LEVEL DISTURBANCE WILL SPREAD RAIN ACROSS OUR REGION 
SATURDAY NIGHT AND FLIGHT CATEGORIES.  NAM SHOWS THE MAJORITY OF 
THIS RAIN OCCURRING FROM 03Z TO ABOUT 10Z SUNDAY...BUT LOW MVFR OR 
IFR CIGS WILL LINGER WELL AFTER THAT.

&&

.PREVIOUS DISCUSSION...

MAIN CHALLENGE TO THE FORECAST WILL BE PRECIPITATION TYPE SATURDAY 
NIGHT IN OVERRUNNING/WAA SETUP.

SURFACE HIGH PRESSURE WAS CENTERED ACROSS THE TENNESSEE VALLEY THIS 
AFTERNOON WITH ITS INFLUENCE ACROSS THE OHIO VALLEY ALLOWING FOR 
SUNNY SKIES ACROSS CENTRAL INDIANA EARLY THIS AFTERNOON WHICH HAS 
ALLOWED TEMPERATURES TO WARM TO AROUND 30 DEGREES. WEAK PRESSURE 
GRADIENT HAS ALSO ALLOWED FOR MUCH LIGHTER WINDS THAN YESTERDAY. 
UPPER PATTERN FEATURED FAST NORTHWEST FLOW ACROSS THE OHIO VALLEY.

MODELS ARE IN GOOD AGREEMENT ON KEEPING SKIES CLEAR TONIGHT WITH AN 
INCREASE IN MID AND UPPER CLOUDS ON SATURDAY IN THE FAST PACFIC 
FLOW. WITH CLEAR SKIES TONIGHT BUT LIGHT SOUTH FLOW...LOOKS LIKE A 
COMBO BETWEEN THE WARMER NAM AND COOLER GFS. TOMORROW...WITH WARM 
AIR ADVECTION KICKING IN STRONG...BUT INCREASE IN CLOUDS...PREFER A 
COMBO BETWEEN THE WARMER GFS AND COOLER NAM. 

MODELS ARE NOW TRENDING WARMER SATURDAY NIGHT AND SOUNDINGS AND 
BUFKIT SUGGEST PREDOMINATELY A RAIN EVENT SATURDAY NIGHT. MODELS AND 
300K LVL ISENTROPIC ANALYSIS ALSO ALL SUGGEST THE RAIN WILL SPREAD 
QUICKLY NORTHEAST AFTER 00Z SUNDAY WITH THE BEST CHANCE BEING FROM 
03-09Z. SOUNDINGS DO INDICATE POTENTIAL FOR THE PRECIPITATION TO 
BRIEFLY START AS SNOW DUE TO EVAPORATIVE COOLING AS THE LOWER LEVELS 
START OUT DRY. HOWEVER...DO NOT THINK THIS WILL LAST LONG ENOUGH TO 
MENTION AS STRONG WARM AIR ADVECTION COMMENCES AND THE SOUNDINGS 
WARM DRAMATICALLY BY 06Z SUNDAY. WILL ALSO MOVE POPS INTO THE LIKELY 
CATEGORY AS ALL THE MODELS ARE TRENDING TOWARDS MORE COVERAGE. THE 
MODELS ARE ALSO TRENDING QUICKER TO MOVE THE RAIN OUT...SO WILL NOW 
ONLY GO WITH A SMALL CHANCE OF RAIN SUNDAY MORNING ACROSS ROUGHLY 
THE EASTERN HALF.

WILL KEEP SMALL POPS GOING MONDAY AND MONDAY NIGHT AS A COLD FRONT 
MOVES THROUGH. CONTINUE TO LIKE RAIN WITH POSSIBLE MIX MONDAY NIGHT 
AS THE COLDER AIR MOVES IN. REST OF THE FORECAST LOOKS DRY AND 
COLDER AS CANADIAN HIGH PRESSURE BUILDS IN ONCE AGAIN. 

&&

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

&&

$$

PUBLIC...KOCH 
AVIATION...JH