Issued by NWS Central Illinois
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000 FXUS63 KILX 291526 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1026 AM CDT WED OCT 29 2008 .DISCUSSION... ISSUED 1025 AM CDT WED OCT 29 2008 FORECAST IS ON TRACK TODAY AND WILL ONLY MAKE MINOR UPDATES TO THE HOURLY GRIDS. SUNNY SKIES TODAY WITH NW WINDS OF 5 TO 15 MPH. MILDER HIGHS IN THE MIDDLE TO UPPER 50S. 15Z/10 AM SURFACE MAP DISPLAYS 1032 MB HIGH PRESSURE OVER LA/MS AND RIDGING NORTHWARD ACROSS MO/MN. VERY STRONG 981 MB LOW PRESSURE WAS OVER CENTRAL QUEBEC NW OF SAGUENAY OVER LAC SAINT-JEAN LAKE WHICH IS STARTING TO WEAKEN AS IT LIFTS NORTHWARD. SUNNY SKIES PREVAILED ACROSS IL THIS MORNING. AFTER DAWN LOWS IN THE UPPER 20S AND LOWER 30S...TEMPERATURES AT 10 AM HAVE RECOVERED INTO THE LOWER TO MIDDLE 40S WITH WNW WINDS 5 TO 15 MPH. ALOFT A VERY STRONG 517 DM 500 MB LOW WAS OVER CENTRAL QUEBEC WITH A LARGE UPPER LEVEL TROF OVER EASTERN NORTH AMERICA. WHILE A 588 DM 500 MB HIGH WAS OVER AZ AND RIDGING NORTHWARD ACROSS THE ROCKIES. IL FIRMLY ENTRENCHED IN A NW UPPER LEVEL FLOW. SHORT RANGE MODELS LIKE THE NAM...RUC AND SREF MODELS ARE SIMILAR IN DRIFTING HIGH PRESSURE RIDGE SLOWLY EAST OVER IL BY SUNSET. ATMOSPHERE REMAINS QUITE DRY THROUGHOUT AND WILL ENSURE SUNNY SKIES TODAY WITH HIGH PRESSURE MOVING IN. STILL HAVE A BIT OF A PRESSURE GRADIENT THIS MORNING SUPPORTING NW WINDS AS HIGH AS 10 TO 15 MPH. THIS PRESSURE GRADIENT GRADUALLY WEAKENS AS HIGH PRESSURE MOVES IN WHICH ALLOWS NW WINDS TO LIGHTEN UP LATER IN THE DAY. 850 MB TEMPS RISE TO BETWEEN 3 AND 6C BY SUNSET WITH COOLEST READINGS NEAR THE EAST CENTRAL IL/IN BORDER. HIGHS SHOULD BE IN THE MID TO UPPER 50S WITH MILDEST READINGS IN THE WEST AND SW WHICH IS ABOUT 10 DEGREES WARMER THAN THE PAST TWO DAYS. THIS IS ALSO CLOSER TO NORMAL HIGHS IN THE UPPER 50S NORTH OF LINCOLN AND LOWER 60S FROM LINCOLN SOUTH. HUETTL && .AVIATION... ISSUED 615 AM CDT WED OCT 29 2008 HIGH PRES RDG FM THE NRN PLAINS TO THE GULF COAST WILL MOVE EWD ACROSS IL TNGT AND BE LOCATED MI-GA BY 12Z THU. WLY/NWLY SFC WNDS AROUND 10 KT AFT 15Z TDY WILL BECOME LGT/VRBL BY 00Z THU. A DRY AIRMASS WILL RESULT IN LITTLE IF ANY CLDS THRU THIS TAF PD. && .PREV DISCUSSION... ISSUED 220 AM CDT WED OCT 29 2008 FEW FORECAST ISSUES WITH THIS PACKAGE...WITH QUIET WEATHER EXPECTED FOR SEVERAL DAYS. MAIN CHALLENGE WILL BE THE EXTENT OF WARMER TEMPERATURES THE NEXT FEW DAYS. SHORT TERM...TODAY THROUGH SATURDAY... CLEAR SKIES PREVAILING OVER THE CWA OVERNIGHT...WITH JUST A FEW HIGH CLOUDS SPILLING SOUTH ALONG EAST EDGE OF HIGH PRESSURE RIDGE OVER THE PLAINS. EXPECT LITTLE IN THE WAY OF CLOUD COVER THROUGH THE EARLY FORECAST PERIOD...AS RIDGE AXIS MOVES EASTWARD INTO THE MISSISSIPPI VALLEY BY THURSDAY MORNING. HIGH TEMPERATURES TODAY EXPECTED TO BE SEVERAL DEGREES WARMER THAN YESTERDAY...WITH MOS GUIDANCE FAIRLY UNIFORM FOR HIGHS. DID TREND A BIT MORE TOWARD THE COOLER MAV GUIDANCE FOR LOWS TONIGHT. THURSDAY AND FRIDAY LOOKING TO BE WELL ABOVE NORMAL...ESPECIALLY ACROSS THE WESTERN CWA. WEAK SHORTWAVE EXPECTED TO MOVE SOUTHEAST INTO MISSOURI BY MIDDAY FRIDAY. ASSOCIATED SURFACE BOUNDARY EXPECTED TO DROP SOUTH ACROSS THE CWA SATURDAY. LITTLE MOISTURE AVAILABLE FOR THIS SYSTEM TO WORK WITH...SO COOLER WEEKEND WEATHER EXPECTED TO BE THE ONLY CONSEQUENCE. HOWEVER...TEMPERATURES WOULD STILL BE NEAR NORMAL FOR THE PERIOD. LONG TERM...SUNDAY THROUGH TUESDAY... NEWEST EXTENDED RANGE MODELS SHOWING SOME DIFFERENCES IN POTENTIAL RAIN CHANCES EARLY NEXT WEEK. ECMWF BRINGS LIGHT QPF INTO THE CWA SUNDAY NIGHT AND MONDAY MORNING...AS A SHORTWAVE SWINGS SOUTHEAST ACROSS THE MIDWEST. GFS DOES NOT SHOW THIS FEATURE...WITH MORE WEST-TO-EAST FLOW ACROSS THE GREAT LAKES AT THIS TIME...PERHAPS DUE TO THE GFS MODELS PLACEMENT OF AN UPPER LOW OVER THE NORTHEAST GULF OF MEXICO...A FEATURE STRONGER AND SLOWER THAN ECMWF INDICATES. HOWEVER...BOTH ARE SHOWING A SLOWER ARRIVAL OF THE NEXT FRONT FROM THE PLAINS. SINCE THESE ISSUES ARE BEYOND THE EDITABLE FORECAST PERIOD...NO CHANGES WERE MADE TO THIS PART OF THE FORECAST AT THIS TIME. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
