FXUS63 KIWX 082339
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
640 PM EST SUN NOV 8 2009
.AVIATION...
SATELLITE SHOWING SCT CIRRUS TO OUR SOUTHWEST MOVING THIS WAY. THESE 
HIGH CLOUDS COUPLED WITH A LIGHT SOUTHERLY WIND OVERNIGHT SHOULD 
HELP LIMIT BR FORMATION. CONDITIONS STILL WARRANT CONTINUING WITH 
MVFR CONDITIONS. WEAK FRONTAL BOUNDARY APPROACHES ON MONDAY WITH 
INCREASING AND LOWERING CLOUDS THROUGH THE DAY. MOISTURE LIMITED SO 
JUST BROUGHT CIGS DOWN TO LOW END VFR FOR NOW BY END OF PERIOD. WIND 
SHIFT WILL ALSO ACCOMPANY THIS FRONT IN THE AFTERNOON.
&&
.SHORT TERM...
SECOND HALF OF A BEAUTIFUL WEEKEND TODAY AS LAST NIGHTS WEAK FRONTAL 
BOUNDARY HAS LIFTED BACK NORTH RESUMING WARM SW FLOW ALLOWING TEMPS 
TO RISE NEAR 70 ACROSS THE CWA.  12Z MODELS INDICATING SOME VERY DRY 
AIR ALOFT WITH DEWPOINT DEPRESSIONS ABOVE H7 AOA 30C WRAPPING 
INTO THE REGION WITH THE LAST GASP OF RIDGING OVER THE SOUTHEAST.  
THIS SHOULD PRECLUDE ANYTHING BUT HIGH CLOUDS TONIGHT AND WITH XOVER 
TEMPS EVEN HIGHER IN THE LOW 50S FEEL THAT SOME PATCHY FOG 
DEVELOPMENT IS POSSIBLE ALTHOUGH THE PRESENCE OF GRADIENT WINDS... 
SOMEWHAT LESS MOISTURE IN THE NEAR SFC LAYER...AND POSSIBILITY OF 
CIRRUS MAKING HEADWAY INTO THE REGION SHOULD MITIGATE THE MORE DENSE 
VARIETY WE SAW THIS MORNING. ADDITIONALLY DEEPER MOISTURE WILL 
POTENTIALLY ARRIVE JUST BEFORE DAWN IN THE WEST PUTTING A CLAMP ON 
TEMPERATURE DROP .
SFC LOW PRESSURE TO OUR NW TODAY WILL RAPIDLY PROGRESS THROUGH 
SOUTHERN QUEBEC TO THE CANADIAN ATLANTIC COAST THROUGH MONDAY NIGHT 
TRAILING A LONG COLD FRONT THAT BECOMES SLOW MOVING AS UPPER FLOW 
LARGELY PARALLELS THE BOUNDARY THROUGH THE PERIOD.  RESULTANT LOW 
LEVEL CONVERGENCE ASSOC WITH FRONTAL PASSAGE IS UNIMPRESSIVE AND 
INSTABILITY AHEAD OF THE FRONT ON MONDAY AFT/EVENING IS SIMILARLY 
PALE WITH LI/S OF -1/-2 AND MUCAPES AOB 200J/KG.  ADDITIONALLY BUFR 
SOUNDINGS SHOW CONSIDERABLE WARM AIR ALOFT TRASHING LAPSE RATES. 
WILL THEREFORE NOT INTRODUCE THUNDER WORDING...AND CONTINUE THE 
GOING TREND OF POPS FROM NW TO SE ALONG AND POST-FRONTAL AS LOW 
LEVELS ATTEMPT TO SATURATE WITHIN MODEST MOISTURE INCREASE WITH 
PASSAGE OF THE FRONT.  MINOR ADJUSTMENTS MADE TO POPS BASED ON 12Z 
MODEL TIMING BUT THE GENERAL APPROACH REMAINS INTACT.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
CONFIDENCE IS STARTING TO WANE FOR THE EXTENDED FORECAST AS THE 
MOVEMENT AND EVENTUAL EXTRATROPICAL TRANSITION OF IDA THIS WEEK WILL 
PLAY A STRONG ROLE IN AUGMENTING THE DOWNSTREAM FLOW PATTERN WITH 
RAMIFICATIONS IN THIS AREA.  THIS LOSS OF CONFIDENCE IS SHOWN WELL 
IN THE GEFS RMOP GRAPHICS...WHICH FROM LAST NIGHT/S 00Z SIMULATION 
SHOW LESS THAN A 20 PERCENT PROBABILITY OF THE GEFS MEAN FORECAST 
VERIFYING BY THE END OF THE PERIOD.  BELIEVE THAT THE MAIN IMPACT OF 
IDA WILL LIKELY BE TO SLOW DOWN THE UPSTREAM FLOW PATTERN AS BOTH 
THE GFS/ECMWF SHOW A PRETTY INTENSE CUT OFF LOW FORMING OFF THE 
EASTERN US COAST BY THE WEEKEND.  
OUTSIDE OF IDA...THE CORE OF LOW HEIGHT ANOMALIES OVER EASTERN 
SIBERIA WILL MOVE EAST...TAKING UP RESIDENCE OVER ALASKA.  THIS WILL 
PUSH A LOW HEIGHT ANOMALY CURRENTLY OVER THE GULF OF ALASKA INTO THE 
WESTERN NOAM...WITH IT/S EASTWARD PROGRESS TOWARDS OUR AREA IMPEDED 
BY THE ABOVE MENTIONED IMPACTS OF IDA.  
FRONT PASSING TO START THE PERIOD WILL TAKE ON A ANA-FRONT STRUCTURE 
WITH CONTINUED LIFT WELL BEHIND THE LLEVEL FRONTAL BOUNDARY.  GIVEN 
THIS STRUCTURE...AND THE INCREASED AMOUNT OF DOWNSTREAM 
BLOCKING...EXPANDED TUESDAY AFTERNOON POPS NORTH AND WEST...AND THIS 
TREND MAY HAVE TO BE FURTHERED BY LATER SHIFTS.  CLOUDS/PRECIP 
CHANCES WILL ALSO KEEP TEMPS DOWN...AND WILL CONTINUE CONSERVATIVE 
HIGH TEMP FORECAST...WITH TEMPS IN THE LOWER/MIDDLE 50S...A LITTLE 
BELOW FULLY MIXED T92 VALUES.  
THE NICE STRETCH OF MID/LATE WEEK WEATHER STILL APPEARS TO BE IN 
TACT WITH SURFACE RIDGING BUILDING IN FOR THE WEDNESDAY-FRIDAY TIME 
PERIOD.  TEMPS WEDNESDAY WILL NOT REBOUND EVEN WITH MORE SUN AS COLD 
ADVECTION ON THE WESTERN FLANK OF DEVELOPING EAST COAST CUTOFF WILL 
LOWER T92 TO AROUND 3C.  BY THURSDAY AND FRIDAY...EXPECT MODERATING 
TEMPERATURES AS RIDGING ALOFT SHOULD BEGIN BUILDING IN FROM THE WEST 
AND ALLOW TEMPS ALOFT TO REBOUND.  HIGHS IN THE MID/UPPER 50S LOOK 
GOOD GIVEN T92 7-8C.  
BY NEXT WEEKEND...WESTERN CONUS TROUGHING SHOULD CONTINUE TO SLOWLY 
TRUDGE EAST...GIVEN PERSISTENT WESTERLY FLOW UPSTREAM SOUTH OF THE 
ALASKA LOW HEIGHT ANOMALY.  HOWEVER...GIVEN THE DOWNSTREAM BLOCKING 
INFLUENCE OF IDA OR IT/S REMNANTS...EXPECT THAT IT WILL TAKE MOST OF 
THE WEEKEND FOR ANY FRONTAL SYSTEM TO REACH OUR AREA.  THEREFORE... 
WILL KEEP SATURDAY DRY...BUT INTRODUCE CHC POPS SATURDAY 
NIGHT/SUNDAY.  CERTAINLY LOW CONFIDENCE AT THIS RANGE...BUT GIVEN 
THE PROXIMITY OF THE TROUGH...BELIEVE POPS AT OR ABOVE CLIMO /ABOUT 
30 PERCENT AT SBN-FWA / ARE WARRANTED.   WILL CONTINUE TEMPS ABOVE 
CLIMO SATURDAY...AND THEN TREND TO JUST ABOVE CLIMO SUNDAY GIVEN 
UNCERTAINTY IN THE TIMING OF THE ARRIVING TROUGH.  THIS YIELDS MID 
50S FOR HIGHS SATURDAY...AND LOWER 50S SUNDAY. 
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...LUD 
LONG TERM...ARNOTT
AVIATION...LASHLEY