000 FXUS63 KLOT 081802 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1202 PM CST SUN NOV 8 2009 .DISCUSSION... 1112 AM CST NO SIGNIFICANT CHANGES TO FORECAST PLANNED THIS MORNING. MSAS DATA INDICATING AREA OF EXPANDING SFC PRESSURE FALLS FROM EASTERN NEBRASKA INTO NORTHERN IOWA IN RESPONSE TO FRONTAL BOUNDARY WHICH PASSED ACROSS NORTHERN ILLINOIS LAST NIGHT BEGINNING TO LIFT BACK NORTHWARD AS A WARM FRONT. THIS WARM ADVECTION NORTH OF THE FRONT HAS PROMOTED A DECK OF MID/HIGH LEVEL CLOUDS WITH SOME CONVECTIVE NATURE DUE TO PRESENCE OF STEEP ELEVATED LAPSE RATES...WITH VIRGA NOTED FROM THESE HIGHER CLOUDS. SATELLITE TRENDS SUGGEST THIS AREA OF MID/HIGH CLOUDS WILL WORK EAST OF THE FORECAST AREA THIS AFTERNOON LEAVING MOSTLY SUNNY SKIES. MIXING UP TO ABOUT 900 HPA FROM ACARS SOUNDINGS COMBINED WITH A FEW MORE DEGREES OF WARMING TO ACCOUNT FOR LOW LEVEL WARM ADVECTION TODAY DOES YIELD HIGHS IN THE BALLPARK OF CURRENT FORECAST HIGHS...SO HAVE MADE NO CHANGES WITH AFTERNOON HIGHS IN THE LOWER TO MID 70S. UPDATED GRIDS HAVE BEEN SENT TO MAINLY ACCOUNT FOR PATCHY MID/HIGH CLOUDS AND EARLY MORNING FOG MENTION...BUT NO UPDATED TEXT FORECAST WILL BE SENT WITH FORECAST IN GOOD SHAPE. MARSILI && .AVIATION... 1145 AM CST 1800 UTC TAFS...DIFFUSE SFC WARM FRONT NOW ORIENTED W-E GENLY ALONG I-80 CORRIDOR. THIS BOUNDARY WILL CONTINUE TO PUSH NWD ACROSS TERMINAL AREA...AND BE N OF REGION BY 19Z. SATLT IMAGERY SHOWS A PATCH OF MID/HIGH LVL CLOUDINESS OVR NERN IL...AT LEADING EDGE OF STRONGER WARM ADVECTION PUNCHING ACROSS UPR MS VLY IN ADVANCE OF A LOW PRESSURE AREA OVR OMAHA AREA AT 17Z. THIS CLOUDINESS WILL LIFT NEWD OUT OF AREA BY 19Z. COMBINATION OF INCREASING INSOLATION AND PUSH OF WARM AIR WILL ALLOW LLVL MIXED LYR INCR TO ARND 1800 FT BY MID AFTN. AS A RESULT...SSELY WINDS ARND 10 KT WILL BCM DUE SLY AND INCR A BIT...WITH GUSTS TO NR 20 KTS. WIND SPEED TO SUBSIDE AGAIN BY 23Z AS SFC COOLS WITH SUNSET. EXPECT CONDITIONS TO REMAIN VFR CLR THROUGH THIS EVENING. AS COLD FRONT APCHS AREA LATE TONIGHT-MONDAY MORNING...WINDS TO BCM MORE SWLY WITH SPEEDS DROPPING TO 5-10 KT RANGE. GIVEN HIGH DEW POINT AIR IN PLACE AHEAD OF THIS FRONT...SUSPECT HAZE/FOG WILL DVLP AGAIN OVERNIGHT. HOWEVER...DUE TO INCR IN MID/HIGH LVL CLOUDINESS OVERNIGHT...VIS IS NOT EXPECTED TO DROP BLO MVFR CATEGORY. COLD FROPA NOT EXPECTED UNTIL AFTER 18Z...XCP OVR N CNTRL IL WHERE WINDS WILL LIKELY BE IN THE PROCESS OF SHIFTING FROM SW-N ALREADY BY END OF FCST PERIOD. MERZLOCK && .MARINE... 1129 AM CST A FRONTAL TROUGH LYING ACROSS THE SOUTHERN PORTION OF LAKE MICHIGAN WILL CONTINUE TO LIFT NORTHWARD ACROSS THE LAKE LATE THIS AFTERNOON AND EVENING...AS A LOW PRESSURE LIFTS NORTHEASTWARD FROM THE CENTRAL PLAINS TO SOUTHWEST MINNESOTA BY THIS EVENING. THIS LOW WILL CONTINUE ON ACROSS THE SOO TONIGHT...AND TO WESTERN QUEBEC ON MONDAY. A TRAILING COLD FRONT WILL PUSH SOUTHWARD ACROSS LAKE MICHIGAN ON MONDAY...SHIFTING WINDS INTO THE NORTH AND NORTHEAST. AS A HIGH PRESSURE BUILDS FROM THE NORTHERN PLAINS TO THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY...A COMBINATION OF INCREASING PRESSURE RISES AND SUSTAINED COLD AIR FLOW WILL RESULT IN WINDS INCREASING INTO 15 TO 25 KNOT RANGE. A FULL LENGTH NORTH NORTHEASTERLY FETCH WILL LEAD TO WAVES BUILDING TO AROUND 6 FEET ACROSS THE SOUTH END OF THE LAKE MONDAY NIGHT. MERZLOCK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$