FXUS63 KIWX 261119
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
619 AM EST THU NOV 26 2009

.AVIATION /12Z TAFS/...

TOUGH FLYING CONDITIONS OVER THE NEXT 24 HOURS AS UPPER LEVEL LOW
MOVES OVERHEAD BRINGING WITH IT AN INCREASE IN SHRAS...A FEW WET
SNOW FLAKES...AND CONTINUED LOW CIGS. SBN IS SOLIDLY MVFR WITH FWA
STILL HOLDING ONTO VFR CIGS BUT EXPECT THESE TO DROP TO 2.5KFT
BEFORE VALID TIME. 

AT SBN EXPECT MVFR CIGS WITH OCCASIONAL IFR CIGS IN -RA TO
PERSIST THROUGH THE DAY. CAN/T RULE OUT A FEW WET SNOWFLAKES
MIXING IN FROM TIME TO TIME DURING THE DAY BUT DO NOT EXPECT THESE
TO IMPACT VSBYS ENOUGH TO HAVE A MEANINGFUL IMPACT...ESP WITH THE
OCCASIONAL IFR CIGS. SHRASN WILL CONTINUE THROUGH THIS EVENING
UNDER MVFR CIGS WITH POSSIBLE IMPROVEMENT TO 2.5KFT AFTER MIDNIGHT
WITH SHRASN LIKELY FALLING APART BY THIS POINT AND NOT HAVING
ENOUGH OF AN IMPACT TO WARRANT TAF MENTION.

AT FWA...MVFR CIGS WILL DETERIORATE AND SHRAS MOVE BACK IN BY
EARLY AFTERNOON EXPECT OCCASIONAL IFR CIGS BETWEEN 19-23Z WHEN THE
HEAVIEST PRECIP ARRIVES. AGAIN...COULD SEE A FEW SNOWFLAKES AT
THIS TERMINAL AS WELL. FOR TONIGHT...ONLY GRADUAL IMPROVEMENT WITH
RAIN ENDING BY AROUND MIDNIGHT AND MVFR CIGS PERSISTING THROUGH
THE END OF THE TAF PERIOD.

SOUTHWEST WINDS 12G18KTS WILL VEER WESTERLY AND INCREASE TO
14G20KTS FOR THE DAY TODAY. WINDS WILL CONTINUE TO VEER WEST
NORTHWESTERLY THIS EVENING AND OVERNIGHT...DIMINISHING TO 10-15KTS
AT SBN WHILE CONTINUING 14G20KTS AT FWA.  

&&

.PREV DISCUSSION... /ISSUED 303 AM EST THU NOV 26 2009/ 

SHORT TERM /TODAY THROUGH FRIDAY NIGHT/...

UPPER PATTERN DOESN/T LOOK A WHOLE LOT DIFFERENT THAN 24 HOURS AGO 
AS THE SECOND IN A SERIES OF SHORTWAVES PULLS INTO THE REGION FROM 
THE WEST.  MAIN DIFFERENCE IS THE TEMPERATURE OF THE AIRMASS...WHICH 
HAS COOLED ABOUT 10 DEGREES SINCE YESTERDAY AND WILL BRING PTYPE 
ISSUES INTO TODAY/S FORECAST.

AREA FINDS ITSELF IN A TEMPORARY LULL IN MEANINGFUL PRECIPITATION 
EARLY THIS MORNING WITH DEEP MOISTURE AHEAD OF SURFACE COLD FRONT 
PUSHING EAST OF THE AREA AND DEEPER MOISTURE ASSOCIATED WITH THE 
CORE OF THE UPPER LOW YET TO ARRIVE.  COULD SEE SOME DRIZZLE AS A 
RESULT GIVEN THE LACK OF ICE IN THE CLOUDS /SEEN ON FOG PRODUCT 
IMAGERY OVER SOUTHWESTERN SECTIONS ATTM/ AND CONTINUED UPWARD 
VERTICAL MOTION DUE TO CYCLONIC LLEVEL FLOW.  

BAND OF SHRAS AND SHSN IS LOCATED ON THE NORTHWESTERN FLANK OF THE 
UPPER LOW...WHERE T85S ARE ACTUALLY WARMER...BUT THE BETTER PRECIP 
RATES HAVE DIABATICALLY COOLED THE COLUMN TO SUPPORT A CHANGEOVER.  
THIS GIVES A HINT TO OUR WEATHER TODAY AS ANY SNOW REACHING THE 
GROUND WILL VERY LIKELY BE TIED TO PRECIPITATION RATES AND DIABATIC 
PROCESSES AS LLEVEL WETBULB TEMPS WILL ONLY BE MARGINALLY COLD 
ENOUGH FOR SNOW. 

WITH SPEED MAX NOW ROTATING AROUND THE SOUTHWESTERN FLANK OF THE 
UPPER LOW...IT/S SOUTHWARD PROGRESS IS JUST ABOUT COMPLETE AND IT 
WILL CONTINUE PULLING EAST THROUGH THE DAY.  THIS WILL BRING A 
REGION OF H85 WARM ADVECTION COLLOCATED WITH A BAND OF H85-H7 
DEFORMATION IN FROM THE WEST...WITH CONTINUED LLEVEL CONVERGENCE DUE 
TO CYCLONIC FLOW AS WELL AS A SECONDARY SURFACE TROUGH.  SHRAS WILL 
INCREASE IN COVERAGE FROM NORTHWEST TO SOUTHEAST THROUGH THE 
MORNING...WITH MOST LOCATIONS SEEING PRECIPITATION THIS AFTERNOON AS 
WIND TRAJECTORIES BEHIND THE SURFACE TROUGH AND T85 FALLING TO 
AROUND -5C ALLOW FOR AN INCREASE IN LAKE ENHANCEMENT TO THE 
PRECIPITATION.  WILL MENTION A MIX WITH SNOW THROUGH THE DAY...BUT 
AT THIS TIME...EXPECT THAT PRECIP RATES WON/T BE STRONG ENOUGH LONG 
ENOUGH TO SUPPORT ANYTHING MORE THAN BRIEF CHANGEOVERS WITH NO 
ACCUMS.  

TEMPS WILL BASICALLY REMAIN STEADY TODAY WITH HOMOGENEOUS UPSTREAM 
AIRMASS SUGGESTING THE ONLY PLAYERS IN THE TEMP FORECAST WILL BE 
PRECIP RATES AND LAKE MICHIGAN.  HAVE UNDERCUT MOS HIGHS AGAIN 
STICKING CLOSER TO 3 HOURLY VALUES WHICH WORKED WELL YESTERDAY.  

4KM LOCAL WRF NICELY CAPTURES TRANSITION FROM LAKE ENHANCED TO LAKE 
EFFECT PRECIPITATION TONIGHT AS DEEPER MOISTURE PULLS EAST WITH THE 
UPPER LOW AND T85S CONTINUE TO COOL TO AROUND -7C OVERNIGHT.  WARM 
LAKE MICHIGAN WILL LIKELY KEEP DOWNSTREAM BL TEMPS MARGINAL THROUGH 
THE EVENING BUT CAN/T RULE OUT A FEW INLAND LOCATIONS SEEING A 
DUSTING OF SNOW ON GRASSY SURFACES.  UPSTREAM DEWPOINTS OVER THE 
UPPER MIDWEST ARE ALREADY DROPPING INTO THE UPPER TEENS AND EXPECT 
THAT AS THESE APPROACH LAKE MICHIGAN FROM THE WEST...ANY DOWNSTREAM 
BANDING WILL THIN AFTER MIDNIGHT WITH PRECIP RATES NOT ENOUGH TO 
PRODUCE SNOW ACCUMS AFTER MIDNIGHT.  FOLLOWED MOS 3 HOURLY TEMPS 
THROUGH THE NIGHT...A LITTLE ABOVE GUIDANCE MINS ESP OVER THE 
NORTHEASTERN 2/3RDS OF THE CWA WHICH WILL BE ENTRENCHED IN CLOUDS 
AND SOME PRECIP.

FRIDAY WILL FEATURE GRADUAL IMPROVEMENT AS TEMPS ALOFT WARM...THE 
INVERSION ALOFT LOWERS AND SURFACE RIDGING BUILDS TOWARDS THE AREA. 
WHILE BUFKIT PROGS ARE PRETTY UNIMPRESSIVE IN THE MORNING...EXPECT 
SOME REMAINING SHRASN OVER NORTHEASTERN AREAS GIVEN SUPPORTIVE TEMPS 
ALOFT EARLY WITH A CONTINUED DECENT FETCH.  WE SHOULD FULLY DRY OUT 
BY AFTERNOON WITH STCU BEING THE ONLY REMNANT OF THE EARLIER LAKE 
PRECIP.

CHILLY NIGHT IN STORE SATURDAY NIGHT AS WE SHOULD SEE A GOOD DEAL OF 
CLEARING AS H85 RIDGE PULLS OVERHEAD AND SURFACE RIDGE SLACKENS 
WINDS.  LEANED CLOSER TO THE COOLER GUIDANCE EXCEPT ALONG THE LAKE 
MICHIGAN SHORELINE WHERE ONSHORE LLEVEL WINDS WILL KEEP TEMPS UP A 
FEW DEGREES.  

LONG TERM /SATURDAY THROUGH WEDNESDAY/...

RIDGING ACROSS THE AREA NOW LOOKS TO POTENTIALLY BRING A NICE DAY 
FOR SAT WITH TEMPS WARMING NICELY TO ABOVE NORMAL LEVELS WITH A FAIR 
AMOUNT OF SUNSHINE. HAVE NUDGED TEMPS UP AT LEAST A CATEGORY WITH 
MOST PLACES HEADING FOR UPPER 40S TO AROUND 50. CAN'T ARGUE WITH 
GUIDANCE HINTING AT MORE LIKE 50 TO 53 IN MANY AREAS BUT WILL START 
A BIT OF AN UPWARD TREND FOR NOW. 

TROUGH STILL LOOKS TO ARRIVE FROM ENERGETIC SYSTEM COMING ONTO THE 
WEST COAST. HOWEVER...SEVERAL SOLUTIONS NOW TAKING BRUNT OF ENERGY 
AND DIGGING IT INTO THE SOUTHWESTERN US AND CUTTING OFF A DEEP UPPER 
LOW THAT WILL MEANDER SLOWLY EAST THROUGH THE FIRST HALF OF THE WEEK 
AND THEN EJECT IN RESPONSE TO AN EVEN STRONGER LONG WAVE TROUGH 
WHICH WOULD SHOW SIGNS OF A SIG PUSH OF POLAR TYPE AIR WITH 850 MB 
TEMPS PROGGED IN THE -12 TO -15 C RANGE BY THE NEW ECMWF BY NEXT 
WEEKEND. BUT GETTING BACK TO THE MED RANGE...TROUGH STILL LOOKS TO 
PASS THROUGH SUN NGT INTO MONDAY WITH CHC POPS STILL LOOKING 
REASONABLE. TROUGH WILL REMAIN PROGRESSIVE WITH BRUNT OF THE MSTR 
AND ENERGY SHIFTING AWAY BY MONDAY NIGHT...POSSIBLY ALLOWING FOR 
SOME PEAKS OF SUN. HOWEVER...AS NEXT TROUGH MENTIONED ABOVE DIGS IN 
AND MSTR BEGINS TO STREAM NORTH FROM THE GULF STATES...CLOUD COVER 
WILL LIKELY INCREASE. FOR NOW WILL KEEP THINGS STATUS QUO AFTER 
MONDAY WITH SIG CHANGES TO THE PATTERN POSSIBLE IN THE COMING DAYS. 
TEMPS WILL AVERAGE AROUND OR JUST A BIT BELOW NORMAL THROUGH THE 
REMAINDER OF THE PERIOD. 

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EST FRIDAY FOR LMZ043-046.

&&

$$

SHORT TERM...ARNOTT
LONG TERM...FISHER
AVIATION...ARNOTT