FXUS63 KIND 090237 AAA
AFDIND

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
935 PM EST TUE DEC 8 2009

.UPDATE...WILL BE BUMPING UP THE START TIME ON THE WIND ADVISORY TO 
090900Z. THINGS SEEM TO BE MOVING A LITTLE FASTER THAN PREVIOUSLY 
EXPECTED...WITH OCCLUSION ALREADY INTO SOUTHWEST ILLINOIS. LOOKS 
LIKE FRONTAL PASSAGE WILL BE IN THE 090600Z-090900Z TIME FRAME. 
GIVEN THE RAPID DEEPENING OF SURFACE LOW EXPECTED AFTER 090600Z AND 
THE UNIDIRECTIONAL FLOW THROUGH 850MB AFTER FRONTAL PASSAGE...
CONCERN FOR WIND GUSTS APPROACHING ADVISORY CRITERIA IN THE WAKE OF 
FRONT.

WILL ALSO CUT POPS INTO THE CHANCE CATEGORY AFTER 090900Z AS FRONT 
SHOULD BE EXITING THE AREA BY THEN. STILL LOOKS LIKE AIR MASS WILL 
REMAIN WARM ENOUGH THROUGH MID MORNING WEDNESDAY FOR JUST A RAIN 
THREAT.

&&

.AVIATION...DISCUSSION FOR 090000Z TAF ISSUANCE. WIDESPREAD LIGHT TO 
MODERATE RAIN OCCURRING ACROSS THE LOCAL AREA. IFR CIGS...005-008 
ABOVE GROUND LEVEL...HAVE BEEN CREEPING NORTH OVER THE PAST FEW 
HOURS...AND APPEAR TO BE JUST SOUTH OF KIND. IFR CONDITIONS EXPECTED 
TO OVERSPREAD KIND/KLAF BY 090200Z. MID LEVEL DRY SLOT CURRENTLY 
PUSHING INTO SOUTHWEST ILLINOIS...SO HEAVIER RAINFALL MAY TEND TO 
TAPER OFF IN INTENSITY ACROSS THE TERMINALS AFTER 090300Z OR SO. 
OCCLUSION LOOKS TO PASS THROUGH AROUND 090700Z-090900Z...SO WILL 
KEEP THE IFR CONDITIONS GOING UNTIL THEN...WITH CIGS IMPROVING INTO 
THE MVFR CATEGORY AFTER PASSAGE OF OCCLUSION.

WILL PROBABLY SEE OCCASIONAL SURFACE WIND GUSTS TO AROUND 25 KTS FROM 
090-110 HEADINGS THIS EVENING...WITH WINDS TENDING TO TEMPORARILY 
TAPER OFF AS OCCLUSION APPROACHES. WIND SHIFT WITH OCCLUSION SHOULD 
BE SHARP...WITH A RAPID VEERING OF WINDS TO 210-230 HEADINGS ALONG 
WITH SOME GUSTS IN THE 30-35 KT RANGE. 

CORE OF 850MB JET EXPECTED TO GENERALLY PASS SOUTHEAST OF THE STATE 
THIS EVENING BASED ON MODEL DATA...SO ALTHOUGH THERE MAY BE SOME 
WIND SHEAR BETWEEN 090300Z-090900Z...DOESN/T LOOK LIKE IT WILL MEET 
CRITERIA AT THIS POINT.

&&

.DISCUSSION...

NEAR TERM...
STRONG LOW PRESSURE WAS FOUND NEAR THE TEXAS PANHANDLE EARLY THIS 
AFTERNOON ALONG WITH A WARM FRONT THAT EXTENDED EAST TO THE 
TENNESSEE RIVER VALLEY. ON THE SOUTH SIDE OF THE FRONT TEMPERATURES 
AND DEWPOINTS WERE IN THE WARMER 40S AND EVEN 50S ACROSS SOUTHWEST 
TENNESSEE. MEANWHILE COLD EASTERLY FLOW WAS IN PLACE ON THE NORTH 
SIDE OF THE FRONT...AND INDIANA. ACROSS CENTRAL INDIANA TEMPERATURES 
WERE IN THE MIDDLE 30S AND DEWPOINTS WERE IN THE LOWER 30S. RADAR 
MOSAICS SHOW FIRST BATCHES OF PRECIPITATION PUSHING ACROSS CENTRAL 
INDIANA.

MODELS ARE IN PRETTY GOOD AGREEMENT OVERNIGHT AND HAVE USED A BLEND. 
300K GFS ISENTROPIC INDICATES VERY STRONG LIFT THIS EVENING WITH A 
VERY MOIST AIR MASS...SPECIFIC HUMIDITIES OVER 5 G/KG. HENCE WILL 
USE CATEGORICAL POPS TONIGHT AS TIME SECTIONS AND FORECAST SOUNDINGS 
CONFIRM A SATURATED COLUMN. ISENTROPIC LIFT BEGINS TO TAPER OFF 
AFTER 06Z AS DRIER AIR WRAPS INTO THE SYSTEM. HAVE TRENDED RAIN 
CHANCES LOWER TOWARD 10Z. COLD FRONT SHOULD BE JUST WEST OF INDIANA 
NEAR 12Z AND FORECAST SOUNDINGS INDICATE PRECIPITATION SHOULD REMAIN 
RAIN UNTIL THEN. 

STRONG WARM AIR ADVECTION WILL ALSO BE OCCURRING TONIGHT...AS THE 
WARM FRONT SURGES NORTHWARD ON THE NEARLY 70 MPH LOW LEVEL JET. THIS 
WILL PLAY HAVOC WITH A TYPICAL DIURNAL TEMPERATURE TREND. AS H8 
TEMPS RISE TO NEARLY 6C OVERNIGHT...TEMPERATURES ARE EXPECTED TO 
SLOWLY RISE THROUGH THE NIGHT AND LOW TEMPERATURES WILL OCCUR EARLY 
THIS EVENING...RIGHT NEAR 00Z. MAVMOS DOES NOT APPEAR TO BE STRONG 
ENOUGH WITH THE WARM AIR ADVECTION AND HAVE TRENDED WARMER. WOULD 
NOT BE SURPRISED TO SEE A 50 DEGREE TEMPERATURE SOMEWHERE IN CENTRAL 
INDIANA OVERNIGHT. 

SHORT TERM...
FORECAST FOCUS IN THE SHORT TERM IS ON WINDS AND PRECIPITATION 
CHANGEOVER ON WEDNESDAY. MODELS IN DECENT AGREEMENT SO WILL USE A 
BLEND UNLESS OTHERWISE NOTED. STRONGEST UPPER FORCING AS 
SHOWN BY Q VECTOR CONVERGENCE HAS MOVED OUT THE AREA BY 12Z BUT 
FORCING FROM COLD FRONT WILL STILL BE COMING THROUGH. MOISTURE WILL 
BE DROPPING OFF AFTER FRONTAL PASSAGE WHICH LOOKS TO BE ARRIVING IN 
THE WESTERN COUNTIES RIGHT AROUND 12Z AND THROUGH THE ENTIRE AREA BY 
18Z. FOR PRECIPITATION TYPE WITH THE FRONT MOVING THROUGH DURING THE 
12-18Z TIME FRAME HAVE TRIED TO ADD A LITTLE TIMING TO CHANGEOVER. 
SOUNDINGS LOOK LIKE COLD AIR ALOFT WILL ARRIVE BEFORE/OR CONCURRENT 
WITH COLD AIR AT THE SURFACE AND THUS DO NOT HAVE TO WORRY ABOUT 
SLEET OR FREEZING RAIN. HAVE INCLUDED A MIX OF RAIN AND SNOW FOR THE 
WESTERN AND CENTRAL COUNTIES IN THE MORNING BEFORE CHANGING OVER TO 
ALL SNOW IN THE LATE MORNING. FOR THE WEST WILL START OUT WITH 
RAIN...THEN CHANGE TO RAIN AND SNOW IN THE LATE MORNING BEFORE 
BECOMING ALL SNOW BY AFTERNOON. THE TIMING OF THE START OF 
CHANGEOVER IS A LITTLE VARIABLE IN THE MODELS AND WENT WITH THE 
SLOWER TIMING OF COLD AIR ARRIVAL BASED ON THE MODELS UNDERDOING THE 
WARMING GOING ON OVERNIGHT TONIGHT. TIMING OF ALL SNOW IS CONSISTENT 
BY 18Z OVER THE ENTIRE AREA IN ALL OPERATIONAL MODELS AT THIS POINT 
SO AM CONFIDENT ANY PRECIPITATION FALLING AFTER THAT TIME WILL BE 
SNOW. WITH THE MOISTURE MOVING OUT WITH THE FRONT AND LITTLE OTHER 
FORCING BESIDES THE FRONT ITSELF AND THE LOW DO NOT EXPECT MUCH IN 
THE WAY OF SNOW ACCUMULATIONS. NORTHERN COUNTIES CLOSEST TO THE LOW 
COULD SEE THE HIGHEST AMOUNTS WHICH SHOULD STILL BE LESS THAN AN 
INCH. WHILE TEMPERATURES WILL START OUT WARM /IN THE 40S/ EARLY IN 
THE DAY /GOING MUCH HIGHER THAN GUIDANCE BASED ON EARLY DAYTIME 
HIGHS FOLLOWING SIGNIFICANT OVERNIGHT WARMING/ TEMPERATURES ARE 
EXPECTED TO DROP RAPIDLY BEHIND THE FRONT AND SHOULD CONTINUE 
FALLING FOR THE REST OF THE DAY. THE WINDS /DISCUSSED BELOW/ PICKING 
UP WITH FRONTAL PASSAGE SHOULD BE SUFFICIENT TO DRY MOST OF THE 
MOISTURE UP EXCEPT IN SITUATIONS OF LARGE PUDDLES OR PONDING SO DO 
NOT EXPECT A WIDESPREAD ICE SITUATION. 

NOW ON TO THE WINDS...SURFACE LOW WILL STRENGTHEN RAPIDLY AS IT 
MOVES OUT OF THE PLAINS AND INTO THE GREAT LAKES /MOST MODELS 
SHOWING OVER 12 MB DROP IN 12 HOURS/. AFTER FRONTAL PASSAGE WINDS 
WILL BE FAIRLY UNIDIRECTIONAL WITH HEIGHT AND THUS ABLE TO MIX DOWN 
WINDS FROM 3000 TO 5000 FT. THE NAM SHOWS THIS PRODUCING GUSTS FOR A 
FEW HOURS OF OVER 50 KTS. THE GFS KEEPS THE GUSTS IN THE 40S. AFTER 
COLLABORATION WITH SURROUNDING OFFICES HAVE DECIDED TO ISSUE WIND 
ADVISORY FOR TOMORROW. EXPECTING TO SEE WIDESPREAD SUSTAINED WINDS 
OF 30-40 MPH WITH GUSTS OF 45 TO 55 MPH. WOULD NOT RULE OUT A FEW 
GUSTS AROUND 60 MPH BUT AT THIS POINT THINK THESE WILL BE ISOLATED 
AND NOT WIDESPREAD ENOUGH TO WARRANT A HIGH WIND WARNING. STILL 
THESE CONDITIONS WILL BE SUFFICIENT TO SIGNIFICANTLY IMPACT TRAVEL 
ESPECIALLY FOR HIGH PROFILE VEHICLES SUCH AS SEMIS AND RVS. THE 
EFFECT WILL BE THE WORST ALONG NORTH-SOUTH OR NORTHWEST-SOUTHEAST 
ROADS. HOLIDAY DECORATIONS...OUTDOOR FURNITURE...AND TRASH CANS ARE 
ALSO LIKELY TO BE BLOWN ABOUT OR AWAY IF NOT VERY SECURELY FASTENED. 
ISOLATED POWER OUTAGES WILL BE POSSIBLE FROM DOWNED TREE LIMBS.

BY WEDNESDAY NIGHT THE SYSTEM WILL BE PULLING OUT OF THE AREA. THE 
WIND GUSTS COULD CONTINUE TO REACH ADVISORY CRITERIA THROUGH SOME OF 
THE OVERNIGHT HOURS SO WILL KEEP IT GOING THROUGH THEN. WILL HOLD 
ONTO A SLIGHT CHANCE OF SNOW SHOWERS IN THE NORTHEAST FOR SOME 
WRAPAROUND. TEMPERATURES WILL CONTINUE DROPPING THROUGH THE NIGHT 
AND LOWS ARE EXPECTED TO DROP INTO THE LOW TO MIDDLE TEENS. THIS 
WILL LEAD TO WIND CHILLS AROUND DAYBREAK THURSDAY THROUGH MID 
MORNING TO BE BELOW ZERO IN THE NORTH AND JUST ABOVE ZERO IN THE 
SOUTH. WIND CHILLS DURING THE DAY THURSDAY WILL STILL ONLY WARM TO 
THE SINGLE DIGITS ACROSS MOST OF THE AREA WITH TEENS IN THE FAR 
SOUTH.

LONG TERM.../FRIDAY THROUGH TUESDAY/
IN THE EXTENDED PERIOD...ARCTIC AIR WILL BE ENTRENCHED ACROSS THE 
NORTHERN TIER STATES...WHILE A MOIST AND RATHER ACTIVE PATTERN 
OCCURS ACROSS THE SOUTHERN U.S.  

ON FRIDAY HIGH PRESSURE WILL MOVE FROM THE OHIO VALLEY TO MID 
ATLANTIC STATES.  THE EUROPEAN...GEM AND GFS MODELS MOVE AN UPPER 
LEVEL DISTURBANCE ACROSS THE DEEP SOUTH LATE FRIDAY AND FRIDAY 
NIGHT.  THE EUROPEAN BRINGS MOISTURE FROM THIS SYSTEM AS FAR NORTH 
AS INDIANA LATE FRIDAY NIGHT AND SATURDAY...WHILE THE GEM...GFS 
MODELS KEEP PRECIPITATION SUPPRESSED TO THE SOUTH.  HPC WENT CLOSE 
TO THE EUROPEAN.  BUT WITH THE GEM AND GFS COMING IN DRIER WILL 
DOWNPLAY PRECIPITATION A LITTLE.

THIS SOUTHERN SYSTEM MOVES ON TO THE EAST BY SUNDAY.   THE EUROPEAN 
BRINGS AN UPPER LEVEL DISTURBANCE ACROSS OUR AREA BY MONDAY.  BOTH 
THE GFS AND GEM SHOW VERY LITTLE MOISTURE NORTH OF THE OHIO 
RIVER...SO WILL DOWNPLAY PRECIPITATION CHANCES AGAIN TO A SLIGHT 
CHANCE LATER SUNDAY NIGHT AND MONDAY. 

THE 12Z GFS DEVELOPS A STRONG UPPER TROUGH ACROSS OUR REGION BY 
TUESDAY.  IT ALSO TAKES A STRONG SURFACE LOW FROM THE NORTHERN GULF 
TO THE MID ATLANTIC STATES AND IN TURN SPREADS PRECIPITATION ACROSS 
OUR REGION. I HAVE LOW CONFIDENCE ON THIS AND WILL MENTION SLIGHT 
CHANCES OF PRECIPITATION MONDAY NIGHT AND THEN KEEP TUESDAY DRY.

AS FAR AS TEMPERATURES ARE CONCERNED...I TRENDED A FEW DEGREES BELOW 
HPC NUMBERS...BUT NOT QUITE AS COLD AS MEX.  ON MONDAY NIGHT ...I 
WENT SLIGHTLY WARMER THAN HPC TEMPERATURES AS THERE COULD BE QUITE A 
BIT OF CLOUDINESS ACROSS OUR REGION.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 4 AM WEDNESDAY TO 1 AM EST THURSDAY FOR 
INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

UPDATE...JAS
NEAR TERM...JP
SHORT TERM...CP
LONG TERM...JH
AVIATION...JAS/RYAN