890 FXUS63 KILX 162320 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 520 PM CST WED JAN 16 2013 .DISCUSSION... ISSUED 300 PM CST WED JAN 16 2013 COOLER TEMPS WILL LINGER FOR ANOTHER 36 HOURS BEFORE A BRIEF WARM- UP ARRIVES FOR FRIDAY-SATURDAY. THEN A MAJOR AIRMASS CHANGE WILL AFFECT THE AREA FROM SUNDAY THROUGH TUESDAY NIGHT...WITH SOME RECOVERY STARTING WED. PRECIPITATION WILL GENERALLY BE MINIMAL OVER THE NEXT WEEK, EXCEPT FOR A QUICK SHORTWAVE FOR SUNDAY NIGHT AND MONDAY...WITH A DUSTING OF LIGHT SNOW POSSIBLE...MAINLY NORTH OF LINCOLN. SHORT TERM...TONIGHT THROUGH SATURDAY. SOUTHWEST WINDS AND SUNSHINE TODAY HELPED PUSH TEMPS ABOVE NORMAL INTO THE MID TO UPPER 30S. THE SLIGHTLY MILDER AIR WILL REMAIN IN PLACE THROUGH TONIGHT...BEFORE A COLD FRONT ARRIVES FROM THE NORTH. AT 2 PM THIS AFTERNOON...THAT COLD FRONT EXTENDED ACROSS THE UPPER MIDWEST FROM SOUTH DAKOTA INTO SOUTHERN MN AND BACK TO THE UPPER PENINSULA OF MICHIGAN. IT WAS DROPPING SOUTH AND WAS EXPECTED TO MOVE THROUGH CENTRAL IL STARTING THURSDAY MORNING. A BAND OF CLOUDS AND FLURRIES ALONG A TROUGH EXTENDING SOUTH THROUGH EASTERN IOWA WAS POISED TO MOVE ACROSS OUR AREA TONIGHT. WE ADDED A MENTION OF FLURRIES THIS EVENING TO OUR NORTHERN AREAS, GENERALLY NORTH OF I-74. BUFKIT SOUNDINGS ARE SHOWING ENOUGH MOISTURE AND LIFT IN THE LOWER LAYERS TO SUPPORT A FEW FLAKES REACHING THE GROUND THIS EVENING. AS THE TROUGH DEPARTS TO THE EAST AFTER MIDNIGHT...WE LOSE NECESSARY LIFT AND THE FLURRIES SHOULD COME TO AN END. THURSDAY MORNING...THE COLD FRONT WILL DROP SOUTH INTO CENTRAL IL...MOVING SOUTH OF ALL OUR COUNTIES BY LATE AFTERNOON. THE FROPA SHOULD BE DRY WITH ONLY LOW LEVEL MOISTURE AND VERY WEAK LIFT NEAR THE FRONT. AIR TEMPS TOMORROW WILL BE COOLER THAN TODAY...BUT STILL RIGHT AROUND NORMAL IN THE LOW TO MID 30S. FRIDAY...BRISK SOUTHERLY WINDS WILL BEGIN A WARMING TREND THAT WILL LAST THROUGH SATURDAY. 850 MB TEMPS WILL CLIMB FROM MIDNIGHT NUMBERS OF -4 TO -7C...TO LATE AFTERNOON READINGS OF 4C TO 5C. THAT LEVEL OF WARMING COUPLED WITH DRY ADIABATIC WARMING OF THE BOUNDARY LAYER WILL HELP BOOST HIGH TEMPS INTO THE LOW 40S NORTH WITH MID 40S SOUTH. SIMILAR CONDITIONS WILL CONTINUE ON SATURDAY AHEAD OF THE FIRST WAVE OF COLDER AIR SET TO ARRIVE SATURDAY NIGHT. LONG TERM...SUNDAY THROUGH WEDNESDAY. THE COLD FRONTAL PASSAGE ON SATURDAY NIGHT WILL DROP MID LEVEL AIR TEMPS FROM 0C TO +5C TO -7 TO -12C BY 12Z/6AM SUNDAY. THAT FIRST COLD FRONTAL PASSAGE APPEARS TO BE MOISTURE STARVED... WITH NO PRECIP EXPECTED. THE SECOND FRONT WILL HAVE ARCTIC AIR IN TOW...AND A LITTLE MORE MOISTURE...BUT STILL NOT MUCH. BEHIND THAT FRONT...850 TEMPS WILL DROP DOWN INTO THE -19C TO -24C RANGE FROM SOUTH TO NORTH. THAT KIND OF AIRMASS WILL ONLY NEED MODEST LIFT TO SQUEEZE OUT FLUFFY SNOWFALL. WE KEPT THE CHANCE POPS NORTH ON SUNDAY NIGHT INTO MONDAY...WITH SLIGHTS BORDERING THAT AREA DOWN TO I-72. WE CANT RULE OUT THE FLUFFY SNOW ACCUMULATING UP TO AN INCH IN SOME NORTHERN AREAS...BUT WE WONT PUSH SNOW AMOUNTS QUITE THAT HIGH THIS FAR OUT. THE SNOW WOULD HAVE VERY LITTLE MOISTURE CONTENT /SNOW RATIOS OF 50 OR 100 TO 1 POSSIBLE/...TO THE POINT WHERE YOU COULD ALMOST STILL SEE THE GROUND THROUGH ONE INCH OF SNOW. AIR TEMPS WILL PLUMMET WELL BELOW NORMAL WITH THIS AIRMASS CHANGE...AS SUNDAYS HIGHS ONLY REACH INTO THE MID-UPPER 20S...AND MONDAY AND TUESDAY HIGHS IN THE TEENS TO AROUND 20. THE COLDEST LOWS SHOULD COME MONDAY NIGHT/TUES MORN...WHERE BELOW ZERO TEMPS ARE LIKELY ACROSS THE NORTHERN COUNTIES...WITH SINGLE DIGIT READINGS ELSEWHERE. ANY AREAS WITH EVEN LIGHT SNOW COVER COULD DIP 5 TO 8 DEG COLDER THAN NEARBY AREAS WITH NO SNOW. A WIDE RANGE OF LOW TEMPS WILL BE POSSIBLE UNDER THAT AIRMASS. A WARMING TREND IS EXPECTED FOR WED AS THE AIRMASS SLIDES AWAY TO THE EAST-NORTHEAST. THE NEW 12Z ECMWF DELAYS THE DEPARTURE OF THE COLD AIR SLOWER THAN THE 12Z GFS...SO WE KEPT HIGHS A LITTLE COLDER THAN ALLBLEND...WITH READINGS BACK INTO THE MID TO UPPER 20S IN MOST AREAS. SHIMON && .AVIATION... ISSUED 520 PM CST WED JAN 16 2013 LOWER CLOUDS HAVE MOVED INTO THE AREA AND ARE AFFECTING PIA/BMI/SPI AND WILL SOON BE OVER DEC/CMI. CIG HEIGHTS WILL BE ABOVE 3KFT AT ALL PLACES EXCEPT FOR BMI...WHERE IT WILL BE MVFR CIGS. IN THE NORTH FOR PIA/BMI/CMI IT SHOULD REMAIN CLOUDY OVERNIGHT AND INTO TOMORROW MORNING. SPI AND DEC SHOULD SEE CLOUDS SCATTER OUT AFTER A FEW HOURS AS BAND OF CLOUDS IS NARROW AND SHOULD BE AWAY FROM THOSE SITES AFTER 2-3 HOURS. THEN EXPECTING SCATTERED CLOUDS AT ALL SITES TOMORROW EARLY MORNING...THEN CLEAR LATE MORNING THROUGH AFTERNOON. WINDS WILL BECOME NORTHWEST THIS EVENING AND THEN NORTHERLY FOR TOMORROW. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$