FXUS63 KIND 061144
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
644 AM EST SUN DEC 6 2009

.AVIATION...
/12Z TAFS/
CLEAR SKIES PREVAILED OVERNIGHT AS HIGH PRESSURE REMAINED OVER THE
FORECAST AREA. HOWEVER...THE HIGH PRESSURE IS STARTING TO SLIDE TO
THE EAST...AND HIGH CLOUDS ARE STARTING TO FILTER INTO TAF SITES.
CLOUD DECK WILL INCREASE THROUGH THE DAY AS A COLD FRONT
APPROACHES INDIANA.  

THE MAIN CHALLENGE OF TAF PERIOD IS THE TIMING OF TONIGHT/S
SNOWFALL. ANTICIPATE SNOW TO FORM AROUND MON 06Z AT KLAF AND
KHUF...WHILE KIND AND KBMG CAN EXPECT IT CLOSER TO MON 09Z.
CURRENTLY...VFR CONDITIONS ARE EXPECTED...BUT THEY COULD BRIEFLY
FALL TO MVFR CATEGORY DUE TO REDUCED VISIBILITIES DURING PERIOD
OF SNOW.

&&

.PREV DISCUSSION... /ISSUED 315 AM EST SUN DEC 6 2009/ 

DISCUSSION...
MAIN FORECAST PROBLEM FOR THE SHORT TERM IS WHEN THE SNOW WILL 
ARRIVE. TEMPERATURES ON SATURDAY WERE LOWER THEN GUIDANCE. THIS 
MORNING THE LOWS WILL BE BELOW GUIDANCE. TEMPS AT 850 MB ONLY 
INCREASE 2C DURING THE DAY. CLOUDS WILL ALSO BE INCREASING. THE GFS 
HAS BEEN RUNNING TO WARM. DUE TO THIS WILL GO LITTLE BELOW COOLER 
NAM TEMPS. TONIGHT A COLD FRONT MOVES INTO CENTRAL ILLINOIS. FRONT 
HAS BEEN SLOWING UP SOME WITH EACH RUN SO WILL DELAY THE START OF 
THE SNOW UNTIL 06Z IN THE WEST THEN AFTER 09Z IN THE CENTRAL AND 
EAST. HAVE CONTINUED WITH THE LOWER THEN GUIDANCE TEMPS. THIS IS A 
VERY QUICK MOVING FRONT. IT MOVES INTO EASTERN OHIO MONDAY 
AFTERNOON. THE NAM POPS TONIGHT ARE IN THE SINGLE DIGITS WITH THE 
GFS NOT GETTING ABOVE SLIGHT CHANCE. HAVE LOWERED POPS DUE TO THE 
SPEED OF THE SYSTEM. SNOW ACCUMULATION WILL BE A DUSTING TO A COUPLE 
OF TENTHS. HAVE ENDED THE SNOW IN THE WEST DURING THE MORNING AND 
OVER THE ENTIRE AREA BY MID AFTERNOON. HIGH PRESSURE BUILDS INTO THE 
AREA MONDAY NIGHT. GFS IS THE COLDER MODEL SO WILL GO NEAR IT. 

AS FOR THE EXTENDED...AN ACTIVE WEATHER WEEK IS IN STORE. HIGH 
PRESSURE OVER THE EASTERN PARTS OF THE COUNTRY WILL MOVE EAST BY 
WEDNESDAY AS A STRONG...DEVELOPING AND DEEPENING LOW PRESSURE SYSTEM 
APPROACHES FROM OKLAHOMA. ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT 
WITH THE OVERALL SYSTEM...BUT HAVE SLIGHT DIFFERENCES WITH THE 
DETAILS. HENCE WILL USE BLEND FOR NOW. AT THIS TIME IT APPEARS THERE 
SHOULD BE ENOUGH WARM AIR ADVECTION AHEAD OF THE SYSTEM THAT MUCH OF 
THE PRECIPITATION SHOULD BE RAIN. FORECAST SOUNDINGS THAT FAR OUT 
SHOW TEMPERATURES BELOW 750MB ABOVE FREEZING THROUGH 12Z WEDNESDAY. 
COLD FRONT WILL PASS ON WEDNESDAY...BUT DEEP MOISTURE ALSO DEPARTS 
WITH IT AS THE LOW SPEEDS TO THE NORTHEAST. HENCE EXPECT ANY RAIN TO 
SHUT OFF AS THE COLD AIR ADVECTION BEGINS ON WEDNESDAY...HOWEVER 
CANNOT RULE OUT SOME STRAY SNOW SHOWERS. GIVEN THE DEEPENING LOW 
PRESSURE SYSTEM HAVE INCLUDED SOME GUSTY WINDS OVER 30 MPH IN THE 
GRIDS AND WILL CONTINUE TO WATCH THIS CLOSES. WILL MENTION THE 
STRONG WINDS IN THE HAZARDOUS WEATHER OUTLOOK LATER TODAY. 

IN THE WAKE OF THE MID WEEK SYSTEM...COLD AIR AND CYCLONIC FLOW WILL 
KEEP CLOUDS...FLURRIES AND BELOW NORMAL TEMPERATURES ACROSS THE AREA 
ON THURSDAY. WARM AIR ADVECTION BEGINS ON FRIDAY AS A WARM FRONT 
APPROACHES AND THE COLD POOL MOVES NORTHEAST...BUT LIMITED MOISTURE 
AT THIS TIME SHOULD JUST RESULT IN AN INCREASE IN CLOUD COVER.

&&

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

&&

$$

PUBLIC...SH
AVIATION...TDUD