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.
&&

$$