FXUS63 KIND 040824
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
300 AM EST FRI DEC 4 2009

.DISCUSSION...
MAIN CONCERN FOR THE SHORT TERM ARE THE CLOUDS AND THEIR EFFECT ON 
TEMPERATURES. SURFACE TEMPERATURES RUNNING SLIGHTLY BELOW GUIDANCE. 
WITH FORECAST STARTING OUT WITH CLEAR SKIES EXPECT TEMPERATURES TO 
CONTINUE TO GO BELOW GUIDANCE. THE LOWER NAM MIN LOOKS BETTER. 
INDIANA WILL START OUT WITH A STRONG FLOW FROM NW. CROSS SECTIONS 
AND SOUNDINGS HAVE A LAYER OF HIGHER RH MOVING IN DURING THE DAY. 
THIS LOOKS GOOD WITH CLOUDS NW OF INDIANA WHICH WILL MOVE IN. THE 
NAM HAS THE MOST CLOUD COVER AND LOWER TEMPERATURE SO WILL GO CLOSER 
TO THAT. SOME CLOUD COVER WILL REMAIN TONIGHT BUT SHOULD NOT BE 
EXTENSIVE ENOUGH TO SLOW TEMPERATURE DROP. TEMPERATURES ARE TRENDING 
TO BE COOLER THEN FORECAST. WILL GO WITH THEM ESPECIALLY CONSIDERING 
IF SKIES GO MOSTLY CLEAR THEY MAY DROP OFF EVEN MORE. ON SATURDAY 
850 MB TEMPERATURES SHOW THAT THE STRONG WAA WILL NOT TAKE PLACE 
UNTIL AFTERNOON. THIS MAY BE PAST GOOD DAYTIME HEATING. SO WILL 
CONTINUE TO GO CLOSER TO THE COOLER NAM TEMPERATURES. ON SUNDAY SOME 
CLOUDS WILL BEGIN TO MOVE IN AHEAD OF NEXT SYSTEM. PROJECTED 
SOUNDINGS ONLY SHOW BRIEF PERIOD OF WARMING DURING THE AFTERNOON. 
DUE TO THIS WILL GO CLOSER TO THE NAM.

MAIN CHANGE IN FORECAST OCCUR IN THE MID TERM. SUNDAY NIGHT A COLD 
FRONT MOVES THROUGH. ATMOSPHERE IS ALMOST SATURATED UP TO 10K FEET. 
THERE IS SOME FRONTONGEN AT LOWER LEVELS ALONG WITH POSITIVE OMEGA 
VALUES. THROUGH 12Z MONDAY SOUNDING HAVE TEMPS BELOW FREEZING. DUE 
TO THIS WILL GO CHANCE SNOW ENTIRE AREA AFTER MIDNIGHT. WILL 
CONTINUE CHANCE OF SNOW ENTIRE AREA DURING THE MORNING. SYSTEM WILL 
MOVE QUICKLY TO THE EAST. WILL MOVE PCPN OUT OF THE CENTRAL AND S 
DURING THE MORNING BUT SOME WRAP AROUND SNOW MAY CONTINUE IN THE 
NORTH.  

IN THE EXTENDED...FOCUS CONTINUES TO BE ON POTENTIAL SIGNIFICANT 
STORM FOR TUESDAY-WEDNESDAY. AFTER A QUIET SUNDAY...WEAK FRONT WILL 
MOVE ACROSS THE REGION EARLY MONDAY. HAVE INTRODUCED 20 POPS FOR 
ENTIRE FORECAST AREA LATE SUNDAY NIGHT AND EARLY MONDAY AS BOUNDARY 
PASSES THROUGH. 12Z OP GFS/15Z SREF BOTH INDICATE POTENTIAL FOR A 
LIGHT RAIN/SNOW MIX WITH POSSIBLY ENOUGH COLD AIR FOR MAINLY SNOW 
NORTH OF I-70. FOCUS THEN TURNS TO LOW PRESSURE DEVELOPING EAST OF 
THE ROCKIES EARLY TUESDAY...AND PROGRESSING QUICKLY INTO THE OHIO 
VALLEY TUESDAY NIGHT/WEDNESDAY. MAJORITY OF EXTENDED MODELS 
INDICATING LOW PRESSURE WILL AFFECT REGION DURING THE TIME PERIOD 
BUT AS IS TO BE EXPECTED AT FIVE TO SIX DAYS OUT...DIFFER ON THE 
DETAILS FROM RUN TO RUN AND MODEL TO MODEL. 00Z ECMWF/12Z OP GFS 
BOTH FAVORING A LESS AMPLIFIED STORM TRACK THROUGH THE OHIO/ 
TENNESSEE VALLEYS. THIS TRACK WOULD FAVOR COLDER WEATHER AND 
PRECIPITATION TRANSITIONING FROM A WINTRY MIX TO SNOW FROM SOUTH TO 
NORTH. 12Z GFS ENSEMBLE MEAN FAVORING A TRACK DIRECTLY THROUGH 
CENTRAL INDIANA WITH MOST BUT NOT ALL INDIVIDUAL MEMBERS CLUSTERED 
IN THE OHIO VALLEY. 12Z ECMWF SHOWING MAINLY RAIN FOR MUCH OF THE 
AREA WITH A RAPIDLY DEEPENING SYSTEM FOLLOWING A LAKE CUTTER PATH 
INTO THE GREAT LAKES. AT THIS POINT WITH SO MUCH UNCERTAINTY SEVERAL 
DAYS OUT...TRENDED TOWARDS HPC GUIDANCE AND PREVIOUS FORECAST 
THOUGHTS INDICATING A RAIN/SNOW MIX SOUTH AND MAINLY SNOW NORTH.  
WITH GREATER CONFIDENCE ON TIMING IMPACTS...DID INCREASE TO 40 POPS 
TUESDAY NIGHT AND WEDNESDAY. ALSO UNDERCUT TEMPERATURES FOR MUCH OF 
NEXT WEEK...WITH MOST LOCATIONS REMAINING IN THE 30S FOR HIGHS 
THROUGH THE PERIOD. 

&&

.AVIATION...DISCUSSION FOR THE 04/06Z TAFS.

VFR EXPECTED THROUGH THE PERIOD. BROAD UPPER TROUGH WILL BE ROTATING 
THROUGH THE GREAT LAKES THROUGH THE PERIOD...BUT MAIN FORCING WILL 
REMAIN NORTH AND WEST OF THE SITES...SO THE ONLY IMPACT WILL BE A 
REDEVELOPMENT OF CLOUD COVER. CLOUD DECK ASSOCIATED WITH MOST RECENT 
SYSTEM HAS SCATTERED OUT AS IT PUSHES EASTWARD...AND ALL SITES ARE 
NOW VFR. MOSTLY CLEAR SKIES WILL PERSIST OVERNIGHT BEFORE 
ENCROACHING STRATUS DECK UNDER UPPER LOW MOVES IN...AND CUMULUS 
DEVELOPMENT FILLS IN ANY MAJOR GAPS IN COVERAGE. PROFILES INDICATE 
POSSIBILITY THAT CLOUD DECK COULD FLIRT WITH HIGH END MVFR TOMORROW 
AFTERNOON...BUT WITH TROUGH WEAKENING AND PULLING NORTHEAST...THIS 
SEEMS UNLIKELY. CONVECTIVE CLOUD BASES SHOULD BE AROUND 3.5K FEET AT 
LOWEST. WINDS WILL REMAIN AT OR BELOW 10 KNOTS THROUGH THE PERIOD.

&&

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

&&

$$
SHORT TERM...HAINES
EXTENDED...KOCH
AVIATION...NIELD