760  
FXUS63 KILX 190319  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
919 PM CST THU JAN 18 2018  
   
UPDATE
 
 
ISSUED AT 910 PM CST THU JAN 18 2018  
 
DIURNAL TEMP FALLS TONIGHT ARE BEING HELD ON THE SLOW SIDE AGAIN  
BY STEADY SOUTHWEST WINDS OF 10-20 MPH. CIRRUS CLOUDS ARE FLOWING  
OVER THE RIDGE IN THE PLAINS INTO NORTHERN AND CENTRAL ILLINOIS.  
ANY THICKENING OF THAT CLOUD COVER COULD AID IN KEEPING LOW TEMPS  
SLIGHTLY WARMER THAN UNDER CLEAR SKIES. HOWEVER, THE WINDS WILL BE  
THE PRIMARY REASON FOR MILDER LOW TEMPS. OUR EAST-SOUTHEAST  
COUNTIES TEMPS DROPPED OFF MORE SIGNIFICANTLY ALREADY TONIGHT DUE  
TO SNOW COVER, WITH 9 PM TEMPS DOWN INTO THE LOW 20S NEAR  
LAWRENCEVILLE, AND GALESBURG 31, JACKSONVILLE 35. DEWPOINTS REMAIN  
ON THE DRY SIDE, SO THERE IS SOME ROOM FOR TEMPS TO DROP OFF.  
HOWEVER, HAVE TRENDED WARMER WITH LOWS FOR AREAS WEST OF I-57 AND  
MAINTAINED COOLER READINGS EAST OF I-57.  
 
TOMORROW IS LOOKING MILD, WITH MANY MORE AREAS SEEING 40S FOR  
HIGHS, ESPECIALLY WEST OF I-57.  
 
UPDATES THIS EVENING WERE TO THE TEMPS/DEWPOINTS ALONG WITH  
SLIGHT INCREASE TO CLOUD COVER IN THE NW HALF OUR FORECAST AREA.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 301 PM CST THU JAN 18 2018  
 
SOUTHWEST WINDS WILL CONTINUE ACROSS THE AREA TONIGHT AND TOMORROW  
AS HIGH PRESSURE SITS ACROSS THE SOUTHEASTERN US AND A MID LEVEL  
RIDGE BEGINS TO BUILD ACROSS THE EASTERN HALF OF THE US. THIS WILL  
BRING MUCH WARMER AIR INTO THE AREA AND SHOULD SEE TEMPS ABOVE  
FREEZING TOMORROW ACROSS THE WHOLE CWA. SKIES WILL ALSO BE MOSTLY  
CLEAR.  
 
TEMPS WILL FALL BELOW FREEZING OVERNIGHT AGAIN, BUT NEAR TO THE  
LEVEL THEY HAVE BEEN THE PAST WEEK OR SO. AGAIN, MUCH WARMER  
TOMORROW WITH MANY AREAS GETTING INTO THE 40S.  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 301 PM CST THU JAN 18 2018  
 
RIDGE WILL CONTINUE TO BUILD ACROSS THE AREA WITH CONTINUED  
SOUTHWEST FLOW ON THE SFC. THIS WARMER AIR WILL MELT A LOT OF THE  
SNOW INTO FRIDAY NIGHT AND AS AN INVERSION BEGINS TO SETUP, SOME  
FOG WILL BE POSSIBLE LATE FRIDAY NIGHT AND EARLY SAT MORNING. SO  
HAVE ADDED PATCHY FOG FOR THIS PERIOD. THE WAA WILL CONTINUE  
THROUGH THE WEEKEND AHEAD OF THE NEXT WEATHER SYSTEM THAT WILL  
BEGIN TO BRING SOME LIGHT WAA PRECIP TO THE AREA SAT NIGHT INTO  
SUNDAY. WITH THE LIGHT PRECIP AND CONTINUED INVERSION, MORE FOG  
WILL BE POSSIBLE SAT NIGHT INTO SUNDAY. SO WILL UP THE COVERAGE OF  
FOG TO AREAS FOR SAT NIGHT AND SUN. BY SUNDAY NIGHT, ONCE PRECIP  
CHANCES INCREASE TO LIKELY OR HIGHER, THE FOG WILL DISSIPATE OUT.  
THE FRONT SHOULD BE MOVING THROUGH THE LATE SUNDAY NIGHT THROUGH  
MONDAY MORNING WITH ONLY CHANCE OF LINGERING PRECIP MONDAY  
AFTERNOON. MODELS SHOW A DECENT CLEAR AREA COMING INTO THE CWA MON  
AFTERNOON ALONG WITH A LITTLE BIT OF COLDER AIR. SO PRECIP COULD  
BECOME MIXED WITH SNOW IN SOME AREAS TO THE WEST DURING THE  
AFTERNOON AND MONDAY EVENING. BEYOND THIS SYSTEM WEATHER SHOULD  
RETURN TO DRY, THOUGH THE OLDER ECMWF SHOWED SOME KIND OF WEAK  
WAVE MOVING THROUGH THE AREA WED AND WED NIGHT. HOWEVER, GFS AND  
NEWER ECMWF SHOW DRY WEATHER THROUGH THE MIDDLE OF THE WEEK.  
 
TEMPS WILL BEGIN VERY WARM AHEAD OF THE WEEKEND WEATHER SYSTEM BUT  
THEN MODERATE LOWER AFTER THE SYSTEM. STILL LOOKS AS THOUGH  
DAYTIME HIGHS WILL BE ABOVE FREEZING, WITH SOME AREAS GETTING INTO  
THE 40S FOR MON THROUGH THUR.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 600 PM CST THU JAN 18 2018  
 
MAIN CONCERN FOR THAT TAFS WILL BE THE LLWS CONDITIONS TONIGHT  
INTO FRIDAY MORNING. A INCREASING SOUTHWESTERLY LLJ THIS EVENING  
ACROSS CENTRAL IL LOOKS TO PEAK AT 45-50KT AROUND 2K FEET, WITH  
40KT WINDS AS LOW AS 1K FEET. THE LLJ IS PROJECTED TO WEAKEN AFTER  
14Z, AS TURBULENT MIXING INCREASES AFTER SUNRISE. SUSTAINED WINDS  
TONIGHT LOOK TO REMAIN IN THE 10-14KT RANGE OUT OF THE SW, THEN  
INCREASE WITH SOME GUSTS TOMORROW.  
 
THE ONLY CLOUDS OF NOTE WILL BE A WAVE OF CIRRUS STREAMING OVER  
THE UPPER LEVEL RIDGE IN THE PLAINS. NO SIGNIFICANT CLOUDS NOR  
VISIBILITY ISSUES ARE EXPECTED THROUGH 00Z TOMORROW EVENING.  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...SHIMON  
SHORT TERM...AUTEN  
LONG TERM...AUTEN  
AVIATION...SHIMON  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab IL Page Main Text Page