616  
FXUS63 KILX 212333  
AFDILX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE LINCOLN IL  
533 PM CST SAT DEC 21 2024  
   
KEY MESSAGES  
 
- SEASONABLY COOL AND DRY WEATHER WILL PERSIST THROUGH SUNDAY  
EVENING WITH TEMPERATURES TURNING MILDER THEREAFTER WITH HIGHS  
LIKELY IN THE 50S THURSDAY THROUGH SATURDAY.  
 
- PATCHY FREEZING DRIZZLE IS POSSIBLE LATE SUNDAY NIGHT INTO MID  
MONDAY MORNING OVER CENTRAL IL, ESPECIALLY FROM I-74 NORTH.  
OTHERWISE AN UNSETTLED WEEK LIES AHEAD WITH DAILY CHANCES FOR  
RAIN MONDAY THROUGH SATURDAY.  
 
 
   
DISCUSSION  
 
ISSUED AT 300 PM CST SAT DEC 21 2024  
 
MID AFTERNOON SURFACE MAP SHOWS STRONG HIGH PRESSURE (1034+ MB)  
RIDGING FROM JAMES BAY CANADA INTO CENTRAL WI AND WEST CENTRAL  
AND NORTHWEST IL. NEARBY HIGH PRESSURE PROVIDING FAIRLY LIGHT  
WINDS UNDER 10 MPH ALONG WITH A FAIR AMOUNT OF SUNSHINE OVER  
CENTRAL IL. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS (BASES 3-4K  
FT) REDEVELOPED THIS AFTERNOON OVER AREAS ALONG AND SOUTH OF A  
LITCHFIELD TO SHELBYVILLE TO ROBINSON. TEMPS AT 230 PM WERE MOSTLY  
IN THE LOWER 30S IN CENTRAL IL, BUT RANGED FROM THE MID TO UPPER  
20S OVER LIGHT SNOW PACK FROM LACON TO BLOOMINGTON TO RANTOUL  
NORTHEAST, TO THE MID 30S IN SOUTHEAST IL.  
 
DIURNALLY DRIVEN STRATOCUMULUS CLOUDS TO DISSIPATE AT SUNDOWN IN  
SOUTHEAST IL. OTHERWISE FAIR WEATHER IS EXPECTED TONIGHT INTO  
SUNDAY OVER CENTRAL/SE IL AS HIGH PRESSURE DRIFTS EASTWARD ACROSS  
THE GREAT LAKES REGION AND OHIO RIVER VALLEY DURING TONIGHT AND  
INTO QUEBEC AND NY AND RIDGING INTO THE MID ATLANTIC STATES BY  
SUNSET SUNDAY. WILL SEE SOME PASSING MID AND HIGH CLOUDS PASS BY  
INTO SUNDAY ESPECIALLY OVER NORTHERN/NE CWA WHERE SKIES BECOME  
PARTLY TO MOSTLY CLOUDY BY LATE SUNDAY AFTERNOON FROM I-72 NORTH.  
ALSO WILL SEE WINDS VEER MORE SOUTHERLY BY SUNDAY WITH GUSTS  
20-27 MPH SUNDAY AFTERNOON OVER CENTRAL IL AND POSSIBLY A BIT  
HIGHER GUSTS SUNDAY NIGHT OVER AREAS NORTH OF I-70. LOWS OVERNIGHT  
IN THE LOWER 20S, EXCEPT UPPER TEENS FROM I-74 NORTHEAST.  
SEASONABLE HIGHS SUNDAY IN THE UPPER 30S TO AROUND 40F, MILDEST  
FROM SPRINGFIELD SW.  
 
WEAK LOW PRESSURE TO MOVE TO NEAR THE SD/IA BORDER BY SUNSET  
SUNDAY AND LIFT INTO WEST CENTRAL WI BY SUNRISE MONDAY WHILE  
LIFTING A WARM FRONT NE OVER CENTRAL IL DURING SUNDAY NIGHT.  
INCREASE LOW LEVEL MOISTURE OVER CENTRAL AND NORTHERN IL BY  
OVERNIGHT SUNDAY NIGHT INTO MONDAY MORNING TO DEVELOP CHANCES OF  
LIGHT PRECIPITATION/DRIZZLE. SURFACE TEMPS NEAR OR JUST BELOW  
FREEZING INTO EARLY MONDAY MORNING OVER NE CWA COULD GIVE A BRIEF  
PERIOD OF PATCHY FREEZING DRIZZLE MAINLY NE OF LINCOLN. A WEAK  
FRONT PUSHES SE INTO CENTRAL IL MONDAY AFTERNOON AND COULD PRODUCE  
CHANCES OF LIGHT RAIN SHOWERS MAINLY FROM HIGHWAY 51 EAST WHILE  
QPF AMOUNTS WILL BE VERY LIGHT IF THEY HAPPEN AT ALL. MILDER HIGHS  
MONDAY OF 42-48F, MILDEST FROM SPRINGFIELD SW. HAVE 20-40% CHANCE  
OF LIGHT RAIN SHOWERS IN SOUTHEAST IL MONDAY NIGHT AS WEAK FRONT  
PUSHES INTO SOUTHEAST IL LATE MON NIGHT. LOWS MON NIGHT RANGE FROM  
AROUND 30F FROM LINCOLN AND CHAMPAIGN NORTH TO THE MID 30S IN  
SOUTHEAST IL.  
 
A SOUTHERN STREAM STORM SYSTEM/TROF TAKES SHAPE OVER THE SOUTHERN  
PLAINS TUE AND EJECTS INTO THE MS RIVER VALLEY TUE NIGHT INTO  
CHRISTMAS DAY. THIS TO BRING 20-40% CHANCE OF LIGHT RAIN INTO  
CENTRAL IL TUE AFTERNOON WITH LIKELY POPS IN SW IL. HIGHS TUE IN  
THE LOWER 40S CENTRAL IL AND MID 40S SOUTHEAST IL. OUR HIGHEST  
POPS ARRIVE TUE NIGHT WITH LIKELY POPS EAST OF I-55. LOWS TUE  
NIGHT IN THE MID TO UPPER 30S WITH AREAS FROM GALESBURG TO LACON  
NEAR OR JUST ABOVE FREEZING FOR LOWS TUE NIGHT. MODELS DIFFER WITH  
HOW WET CHRISTMAS DAY COULD BE OVER CENTRAL/SE IL WITH GFS PUSHING  
MOST OF QPF EAST OF CWA WED AFTERNOON WHILE GEM AND ECMWF MODELS  
HAVE LIGHT QPF OVER MUCH OF CWA ON WED. NBM POPS ARE BLENDED WITH  
30-50% POPS WED, THOUGH DIMINISH TO SLIGHT CHANCE ALONG AND WEST  
OF IL RIVER WED AFTERNOON.  
 
ANOTHER SOUTHERN STREAM MID/UPPER LEVEL LOW/TROF EJECTS OVER THE  
SOUTHERN ROCKIES WED AND EJECT NE INTO MO OR IOWA BY FRI MORNING  
AND LIKELY BRING MORE RAIN TO THE AREA FROM THU AFTERNOON INTO  
FRIDAY WITH UNSETTLED WEATHER LIKELY CONTINUING OVER IL INTO  
SATURDAY. SOUTH TO SE WINDS CONTINUE TO WARM TEMPERATURES AS WEEK  
PROGRESSES, WITH HIGH 50-55F ON THU- SATURDAY IN CENTRAL IL AND  
MID TO UPPER 50S SOUTHEAST IL.  
 
THE CLIMATE PREDICTION CENTER (CPC) 8-14 DAY OUTLOOK FOR DEC  
29-JAN 4 FAVORS ABOUT NORMAL TEMPERATURES OVER CWA (60% CHANCE OF  
ABOVE NORMAL TEMPERATURES FOR CENTRAL/SE IL).  
 
07  
 
 
   
AVIATION  
(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)  
ISSUED AT 532 PM CST SAT DEC 21 2024  
 
AN AREA OF MID LEVEL CEILINGS CONTINUES TO DRIFT SOUTHEAST OUT OF  
IOWA AND INTO THE AREA. HREF GUIDANCE SUGGESTS THESE WILL SLOWLY  
BREAK UP AS THEY MOVE ACROSS CENTRAL IL, BUT WE'VE ADDED  
SCT090 FOR A PORTION OF THE OVERNIGHT PERIOD TO HINT AT THE  
POSSIBILITY OF BROKEN CEILINGS AROUND FL080 TO FL100. NORTHEAST  
WINDS WILL VEER TO SOUTH-SOUTHEAST OVERNIGHT, AND INCREASE SHARPLY  
MID TO LATE MORNING WITH GUSTS OVER 20 KT LIKELY (60-70% CHANCE)  
BY 17Z (11AM CDT).  
 
BUMGARDNER  
 
 
   
ILX WATCHES/WARNINGS/ADVISORIES  
 
NONE.  
 
 
 
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