Issued by NWS Central Illinois
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000 FXUS63 KILX 251115 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 615 AM CDT SAT OCT 25 2008 .DISCUSSION... ISSUED 210 AM CDT SAT OCT 25 2008 00Z UPPER AIR CHARTS SHOWED VERTICALLY STACKED LOW ACROSS EAST CENTRAL IOWA...WITH LATEST SATELLITE IMAGES SHOWING IT HAVING PUSHED INTO NORTHERN ILLINOIS. CLOUDS ACROSS CENTRAL AND SOUTHEAST ILLINOIS LARGELY SCATTERED OUT DURING THE EVENING...BUT HAVE BEGUN TO INCREASE AGAIN NORTHWEST OF I-55. MAIN FORECAST ISSUE FOR TODAY DEALS WITH THE BLAST OF COLD AIR THAT IS EXPECTED TO MOVE INTO THE AREA SUNDAY AND SUNDAY EVENING...AS WELL AS THE ACCOMPANYING WINDY CONDITIONS. SHORT TERM...TODAY THROUGH MONDAY... CLOSED UPPER LOW EXPECTED TO DEGENERATE INTO A WAVE AS IT LIFTS NORTHEAST INTO MICHIGAN TODAY. EXPECT ANY LINGERING PRECIPITATION WITH THIS FEATURE TO REMAIN TO OUR NORTH. EARLY MORNING CLOUDINESS SHOULD GIVE WAY TO MOSTLY SUNNY CONDITIONS BY LATE AFTERNOON...AS HIGH PRESSURE PASSES TO OUR SOUTH. COLDEST AIR OF THE SEASON EXPECTED TO BEGIN MOVING INTO THE AREA ON SUNDAY...AS FRONTAL BOUNDARY PUSHES SOUTHEAST. WHILE SOUTHEAST CWA WILL SEE TEMPERATURES RISE INTO THE 60S ON SUNDAY AFTERNOON... NORTHWEST PORTIONS ARE EXPECTED TO HAVE FALLING TEMPERATURES INTO THE 40S. COLD AIR WILL ARRIVE IN EARNEST BY MONDAY MORNING. MUCH OF THE FORECAST AREA IS EXPECTED TO SEE ITS FIRST FREEZING CONDITIONS OF THE SEASON. HARD FREEZE IS LIKELY ACROSS THE NORTHERN CWA...WITH TEMPERATURES FALLING INTO THE UPPER 20S. WELL BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH THE DAY. ANOTHER SIGNIFICANT FACTOR WILL BE THE WINDS BEHIND THE FRONT. 150 KT JET EXPECTED TO BE JUST TO OUR NORTH BY MIDDAY SUNDAY...WITH 50 KTS ALOFT AS LOW AS 800 MB. SUSTAINED SURFACE WINDS OF 20-30 MPH WILL BE LIKELY ACROSS MUCH OF THE FORECAST AREA LATE SUNDAY MORNING THROUGH THE AFTERNOON...GUSTING IN THE MID 30S. MAY NEED A WIND ADVISORY AT SOME POINT...BUT WILL DEFER THE DECISION TO DAY SHIFT FOR NOW. LONG TERM...TUESDAY THROUGH FRIDAY... QUIET WEATHER EXPECTED INTO THE MIDDLE OF THE WEEK...AS HIGH PRESSURE RIDGE BUILDS EAST ACROSS THE MISSISSIPPI VALLEY. SIGNIFICANT TEMPERATURE RECOVERY EXPECTED AS THE WEEK PROGRESSES...WITH SOUTHWEST WINDS RESULTING FROM HIGH PRESSURE CENTER MOVING ACROSS THE LOWER MISSISSIPPI VALLEY. NO CHANGES MADE TO THE FORECAST BEYOND WEDNESDAY MORNING. GEELHART && .AVIATION... ISSUED 615 AM CDT SAT OCT 25 2008 DEEP LOW PRES SYS HAS DEPARTED TO THE NE OF IL...HOWEVER LOW LEVEL MOISTURE WILL CONT TO WRAP SEWD INTO THE AREA. AREAS OF LOW CLDS WILL CONT THIS MORNING TIL AROUND 15Z WHEN CIGS SHOULD LIFT TO OR ABOVE 3K FT. SUNSHINE WITHIN CLEAR AREAS THIS MORNING SHOULD FILL BACK IN WITH MORE STRATOCU...THEN ALL OF THE CLOUDS WILL DEPART AROUND 00Z SUN. DOPPLER RADARS AND PROFILERS ARE SHOWING NWLY WINDS 20-30 KT IN THE LOWEST 2K FT OF THE ATMOSPHERE...AND THESE WINDS WILL MIX DOWN AS THE LOW LEVEL INVERSION BREAKS DOWN. AT THE SURFACE...EXPECT 14-18 KT SUSTAINED WITH GUSTS TO 25 KT 16Z-23Z. GUSTS WILL DIMINISH WITH SUNSET TONIGHT...BUT THE SFC PRES GRADIENT WILL REMAIN SUFFICIENT FOR A 10-12 KT WIND THRU 12Z SUN. 04 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
