FXUS63 KIND 070829
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
245 AM EST MON DEC 7 2009

.DISCUSSION...
MAIN FORECAST CHALLENGER FOR THE SHORT TERM IS THE TIMING OF THE 
SNOW. THIS MORNING A COLD FRONT EXTENDED FROM EXTREME NW ILLINOIS TO 
LOW OVER WEST CENTRAL MO TO OK. AN AREA OF PVA IS MOVING THROUGH 
CENTRAL INDIANA DURING THE EARLY MORNING. INSTABILITY IS WEAK WITH 
THIS SYSTEM. ALL MODELS ARE IN AGREEMENT WITH THE ONLY AREA THAT 
BECOMES CLOSE TO SATURATION IS FROM 2500 FT TO 4500 FEET. AREA OF 
SNOW IS MOVING CLOSE TO 50 MPH. RECEIVED A REPORT THAT SNOW BEGAN AT 
230 AM IN EXTREME SW INDIANA. WITH SPEED OF SYSTEM AND LIMITED  
MOISTURE ACCUMULATION WILL BE AT THE MOST .2 INCH. WILL BE OVER BY 
MORNING RUSH HOUR IN THE WEST AND ABOUT TO END IN THE CENTRAL 
SECTIONS. WILL CONTINUE IT UNTIL MID MORNING IN THE EAST. LAST 
SEVERAL DAYS COOLER NAM HAS VERIFIED WELL WITH HIGH TEMPS SO WILL 
CONTINUE TO USE THOSE TEMPS. THIS COLD FRONT MOVES THROUGH DURING 
THE AFTERNOON. NOT MUCH OF A TEMPERATURE DIFFERENCT BEHIND THIS 
FRONT. HIGH PRESSURE SWEEPS THROUGH TONIGHT. AS HIGH MOVES EAST IT 
WILL PULL WARMER AIR INTO AREA. MODELS SHOW 850 MB TEMPS INCREASING 
3-5 DEGREES DURING THE DAY. MODEL TEMPS DO COME INTO FAIRLY CLOSE 
AGREEMENT SO WILL EITHER SPLIT THE DIFFERENCE OR GO TOWARD THE COOL 
TEMP DUE TO CLOUD COVER LIMITING WARMING AND CHANCE OF RAIN DURING 
THE AFTERNOON. 

MAIN CONCERN IS THE WIND ON WEDNESDAY. LOW PRESSURE MOVES OUT OF OK 
TUESDAY NIGHT AND DEEPENS AS IT MOVES INTO EXTREME NW INDIANA AROUND 
SUNRISE WEDNESDAY MORNING. A STRONG COLD FRONT EXTENDS SOUTH OF THE 
LOW. WARM AIR WILL CONTINUE BE PULLED INTO AREA TUESDAY NIGHT AND 
EARLY WEDNESDAY MORNING. MODELS IN AGREEMENT WITH THIS WARMING WHICH 
WILL KEEP PRECIPITATION AS RAIN. AS THE COLD FRONT MOVES THROUGH ON 
WEDNESDAY THERE WILL BE A STEADY DROP IN TEMPERATURES. TEMPERATURES 
WILL DROP AROUND 10 DEGREES DURING THE DAY. WILL GO WITH RAIN OR 
SNOW DURING THE MORNING BUT THIS WILL QUICKLY CHANGE OVER TO SNOW BY 
AFTERNOON. GFS AND ECM ARE IN AGREEMENT WITH 50 KT WINDS AROUND 3000 
FEET ON WEDNESDAY. BUFKIT SHOWS WIND AROUND 35 KTS COULD TRANSFER TO 
SURFACE. WILL GO WITH THAT VALUE FOR GUSTS. HIGH WINDS WILL CONTINUE 
WEDNESDAY NIGHT BUT GUSTS WILL DECREASE AS LOW CONTINUES TO MOVE NE 
AND PRESSURE GRADIENT DECREASES. 

AFTER THIS ACTIVE AND QUICK MOVING WEATHER SYSTEMS HIGH PRESSURE 
WITH MORE ZONAL FLOW WILL MOVE IN. THIS WILL GIVE DRY CONDITIONS 
FROM THURSDAY ON. DID NOT DEVIATE FROM GUIDANCE TEMPS MUCH.

&& 

.AVIATION...DISCUSSION FOR THE 06Z TAFS.

LATEST MODELS ARE MORE IN LINE WITH RADAR TRENDS AND ISENTROPIC 
ANALYSIS AND SUGGESTS PRECIP WILL MOVE INTO THE WESTERN TERMINALS BY 
06Z AND EASTERN ONES BY 08Z. MOST OF THE UPSTREAM PRECIPITATION IS 
IN THE FORM OF SNOW...BUT WOULDN'T BE SURPRISED TO SEE FREEZING 
DRIZZLE FOR A TIME BASED ON BUFKIT. CEILINGS WERE FALLING TO MVFR 
JUST BEHIND THE ONSET OF THE SNOW...SO WILL MOVE UP MVFR TO 06Z AND 
08Z RESPECTIVELY AS WELL. ALSO...WILL MOVE THE END TIME UP A FEW 
HOURS CLOSER TO 14Z EASTERN TAF SITES AND 16Z WESTERN ONES BASED ON 
SPEED OF THE RESPONSIBLE UPPER DISTURBANCE. MVFR TO CONTINUE THROUGH 
THE REMAINDER OF THE TAF PERIOD BASED ON UPSTREAM CONDITIONS AND 
MODEL TIME SECTIONS. FINALLY...WINDS WILL NOT BE A FACTOR LESS THAN 
10 KNOTS.

&&

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

&&

$$

PUBLIC...SH
AVIATION...MK