000 FXUS63 KIWX 181736 AFDIWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1236 PM EST TUE NOV 18 2008 .AVIATION.../18Z TAFS/ MAINLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD. THERE WILL BE A FEW AREAS OF MVFR CIGS AND POSSIBLY VISBY OVER FAR NORTHWESTERN PORTIONS OF THE FA FROM RESIDUAL LAKE EFFECT SHOWERS THIS AFTERNOON. HOWEVER...NOT EXPECTING ANY RESTRICTIONS AT TERMINALS. SKIES WILL GENERALLY CLEAR TONIGHT SAVE FOR SOME ADVANCING CIRRUS IN RESPONSE TO SHORTWAVE RIDGING. STRONGER FLOW WILL BE LIKELY JUST OFF THE SFC IN THE NW...AS SW WINDS INTENSITY IN RESPONSE TO APPROACHING LOW PRESSURE. && .PREV DISCUSSION... /ISSUED 439 AM EST TUE NOV 18 2008/ SHORT TERM... LK INDUCED MESO VORT DISSIPATING RAPIDLY INLAND OVR NRN MIAMI COUNTY THIS MORNING. TAIL END OF LL CVRG ZONE/SINGLE HEAVY SNOW BAND HAMMERING PORTER COUNTY AS FEARED YDA AND HAD BACKED WWD ENTIRELY OUT OF CWA FOR THE MOMENT. HWVR FLW DISRUPTION BEHIND DECAYING VORT NOT PARTICULARLY STG. LL WIND FIELD ALREADY RECOVERING IN STG LK AGGREGATE TROUGHING TO A MORE MERIDONALLY ALIGNED LONG AXIS FETCH ALG ERN LK SHORE FM JUST WEST OF KBIV NWD TO KLDM WHERE WINDS CONT TO BACK. THIS WILL SPRT REINTENSIFICATION OF SHORE PARALLEL SINGLE BAND THROUGH DAYBREAK WHILE MOVING BACK ONSHORE OVR FAR WRN BERRIEN AND WRN LAPORTE COUNTIES AND THEN ANCHOR GIVEN INTENSIFYING LK BREEZE COMPONENT. BAND WILL BEGIN TO DIMINISH BY EARLY AFTN IN ASSOCN/W INLAND HEATING...LWRG INVERSION HGTS AND EVENTUAL LL FLW COLLAPSE BY LT AFTN. TEMPS ON THE OTHER HAND A TOSS UP GIVEN FREE FALL THIS MORNING ONGOING INLAND WHERE SKIES HAD CLEARED AND LIKELY REDVLPMNT OF SC BY MID MORNING AS WK INSOLATION ENSUES. THUS WILL KEEP W/EARLY MORNING UPDATE OTHER THAN TO CANCEL MARSHALL/FULTON EARLY. LAPORTE AND BERRIEN TO SEE ADDNL SIG ACCUMULATION THROUGH 18Z W/LESSOR AMTS DOWNSHEAR ACRS WRN PORTIONS OF STARKE/PULASKI. TONIGHT FLW BACKS QUICKLY AS RIDGE AXIS DROPS INTO THE TN VALLEY AND APCH OF YET ANOTHER REINFORCING NRN STREAM SW DROPPING SEWD OUT OF WRN CANADA. SOME CLRG THIS AFTN INTO THIS EVE SHLD ALLOW SFC TO DECOUPLE QUICKLY W/RAPID TEMP DROP ESP OVR SNOW COVER SHLD LK CLD PLUME THIN TOO BUT THEN STEADY OUT W/LT SFC GRADIENT DVLPG. OTHERWISE SW FLW DEEPENS WED AHD OF INCOMING SW TROUGH. FAIRLY STG MIXING AND LIMITED INSOLATION WILL PUSH TEMPS INTO THE UPR 30S/LWR 40S AND MELT MOST OF THE SNOW OUTSIDE FAR NW. LONG TERM... THURSDAY THROUGH MONDAY...LAKE EFFECT SNOW SHOULD BE ONGOING EARLY THURSDAY WITH THE POTENTIAL FOR HEAVY SNOW ONCE AGAIN. ALTHOUGH LAKE MICH TEMPS SHOULD BE A LITTLE COLDER THAN DURING THIS PAST EVENT... THE AIRMASS SHOULD ALSO BE A LITTLE COLDER SO DELTA T VALUES CLOSE TO 20 ARE EXPECTED. THE FETCH ACROSS THE LAKE THURSDAY INTO THURSDAY NIGHT LOOKS FAVORABLE FOR LAKE EFFECT SNOW...WITH EVEN SOME PRECONDITIONING FROM LAKE SUPERIOR. SOME WINTER WEATHER HIGHLIGHTS ARE LIKELY AS THIS EVENT GETS A LITTLE CLOSER. OTHERWISE...THERE IS THE POTENTIAL FOR ANOTHER SIGNIFICANT SYSTEM EARLY NEXT WEEK. THE GFS AND THE ECMWF CONTINUE TO BE OUT OF PHASE WITH EACH OTHER CONSIDERING THE TIMING OF THIS SYSTEM. THE GFS HAS TRENDED MUCH FARTHER NORTH WITH THE COLD AIR AND SUPPORTS HIGHS WELL INTO THE 40S SUNDAY AND MONDAY. THE EARLIER ECMWF INDICATED A LOW PRESSURE AREA TRACK TO THE SOUTH OF THE FORECAST AREA...BUT THE LATEST RUN FAVORS A NORTH TRACK AND WARMER TEMPERATURES SUNDAY. FOR NOW...DUE TO THESE UNCERTAINTIES...MADE ONLY MINOR CHANGES TO THESE PERIODS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING FOR LMZ043-046. SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ043- 046. && $$ SHORT TERM...HOLSTEN LONG TERM...SKIPPER AVIATION...CHAMBERLAIN