983  
FXUS63 KILX 190828  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
328 AM CDT SUN APR 19 2015  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 328 AM CDT SUN APR 19 2015  
 
LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW CLOSED UPPER LOW OVER  
EASTERN COLORADO, WITH LEAD SHORT-WAVE ROTATING AROUND THIS FEATURE  
ACROSS ARKANSAS/LOUISIANA. AS THIS WAVE LIFTS NORTHWARD, PRECIP  
WILL EVENTUALLY SPREAD INTO CENTRAL ILLINOIS TODAY. 07Z/2AM RADAR  
MOSAIC SHOWS DRY CONDITIONS ACROSS THE ENTIRE KILX CWA: HOWEVER,  
SHOWERS ARE BEGINNING TO DEVELOP AND BECOME MORE WIDESPREAD FURTHER  
SOUTH ACROSS WESTERN KENTUCKY AND FAR SOUTHERN ILLINOIS. BASED ON  
RADAR TIMING TOOLS AND LATEST HRRR FORECAST, THINK SCATTERED SHOWERS  
WILL ARRIVE SOUTH OF I-70 OVER THE NEXT COUPLE OF HOURS, THEN WILL  
SPREAD NORTHWARD TOWARD THE I-74 CORRIDOR BY MIDDAY. HAVE ADJUSTED  
POPS TO ACCOUNT FOR THE SLOWER ARRIVAL OF PRECIP DURING THE MORNING,  
THEN HAVE GONE WITH CATEGORICAL POPS ACROSS THE BOARD THIS  
AFTERNOON. ASIDE FROM SOME SBCAPES OF AROUND 1000J/KG ACROSS THE  
FAR SE CWA, FORECAST SOUNDINGS REMAIN FAIRLY STABLE TODAY. AS A  
RESULT, AM EXPECTING MAINLY SHOWERS WITH JUST A FEW EMBEDDED  
THUNDERSTORMS. DUE TO CLOUD COVER AND PRECIP, HIGH TEMPERATURES  
WILL BE SEVERAL DEGREES COOLER THAN IN RECENT DAYS, WITH READINGS  
MAINLY IN THE 60S. WARMEST TEMPS OF AROUND 70 WILL BE FOCUSED  
ALONG/WEST OF THE ILLINOIS RIVER WHERE PRECIP WILL BE SLOWEST TO  
ARRIVE.  
 

 
   
LONG TERM
 
(MONDAY THROUGH SATURDAY)  
ISSUED AT 328 AM CDT SUN APR 19 2015  
 
LEAD SHORT-WAVE WILL LIFT INTO NORTHERN ILLINOIS/INDIANA BY EARLY  
EVENING, LIKELY LEADING TO A TEMPORARY LULL IN THE SHOWERS.  
MEANWHILE, THE MAIN UPPER LOW WILL GET A SOLID PUSH EASTWARD AND  
WILL ARRIVE ACROSS ILLINOIS LATER TONIGHT INTO MONDAY MORNING.  
SHOWERS AND PERHAPS A THUNDERSTORM WILL ACCOMPANY THIS FEATURE, SO  
WILL CONTINUE LIKELY POPS TONIGHT THROUGH MONDAY MORNING. ONCE THE  
500MB VORT MAX AND THE ASSOCIATED SURFACE COLD FRONT PASS TO THE  
EAST, RAIN CHANCES WILL COME TO AN END BY MONDAY AFTERNOON. THANKS  
TO A TIGHT PRESSURE GRADIENT BEHIND THE DEPARTING FRONT, STRONG W/NW  
WINDS GUSTING TO BETWEEN 25 AND 30 MPH WILL DEVELOP ON MONDAY. THE  
WINDS WILL SUBSIDE FOR A TIME MONDAY NIGHT, BUT WILL ONCE AGAIN  
INCREASE MARKEDLY DURING THE DAY TUESDAY. HIGH TEMPERATURES BOTH  
DAYS WILL REMAIN IN THE LOWER 60S, WHILE OVERNIGHT LOWS DIP INTO THE  
UPPER 30S AND LOWER 40S.  
 
00Z APR 19 MODELS HAVE COME INTO MUCH BETTER AGREEMENT CONCERNING  
THE EXTENDED FORECAST, WITH CONSENSUS FEATURING A CHILLY AND LARGELY  
DRY WEEK AHEAD. BOTH THE GFS AND ECMWF INDICATE A WEAK COLD FRONT  
WILL PASS THROUGH CENTRAL ILLINOIS TUESDAY NIGHT INTO WEDNESDAY:  
HOWEVER, THEY DISAGREE ON HOW MUCH PRECIP IT WILL GENERATE. THE GFS  
IS SLIGHTLY WETTER AND FASTER WITH FROPA, WHILE THE ECMWF IS DRIER  
AND ABOUT 6 HOURS SLOWER WITH THE FRONT. DUE TO THE STRONG  
NORTHWESTERLY UPPER FLOW PATTERN IN PLACE ACROSS THE MIDWEST, THINK  
THE FASTER GFS IS THE WAY TO GO WITH TIMING, BUT THINK THE DRIER  
ECMWF IS BETTER WITH QPF AS DEEP MOISTURE WILL BE LACKING WITH THIS  
FEATURE. AS A RESULT, HAVE OPTED TO CARRY LOW CHANCE POPS  
EVERYWHERE TUESDAY NIGHT, THEN ONLY ACROSS THE SE CWA ON WEDNESDAY.  
ONCE THE FRONT PASSES, A COOL/CANADIAN AIRMASS WILL SETTLE INTO THE  
REGION FOR THE MIDDLE AND END OF THE WEEK. HIGH TEMPERATURES WILL  
STRUGGLE TO REACH THE 60 DEGREE MARK ON BOTH WEDNESDAY AND THURSDAY,  
WHILE LOWS DROP INTO THE 30S. COLDEST MORNING MAY END UP BEING  
FRIDAY MORNING, WHEN RIDGE OF HIGH PRESSURE IS OVERHEAD AND WINDS  
WILL BE LIGHTEST. WILL NEED TO KEEP AN EYE ON TEMPS, AS FROST  
ADVISORIES WILL BE POSSIBLE ACROSS PARTS OF CENTRAL/SOUTHEAST  
ILLINOIS LATER THIS WEEK. AFTER THAT, ANOTHER SYSTEM WILL APPROACH  
FROM THE SOUTHWEST BY THE END OF THE WEEK: HOWEVER, ITS INFLUENCE  
LIKELY WILL NOT BE FELT UNTIL FRIDAY NIGHT/SATURDAY AT THE EARLIEST.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)  
ISSUED AT 1145 PM CDT SAT APR 18 2015  
 
VFR CONDITIONS CONTINUE ACROSS CENTRAL IL TAF SITES THIS EVENING  
AS A COMPLEX PATTERN OF A LARGE SCALE CENTRAL U.S. TROUGH WITH  
MULTIPLE EMBEDDED DISTURBANCES DEVELOPS. MAINLY VFR CONDITIONS  
EXPECTED UNTIL AROUND 12Z WHEN THE FIRST EMBEDDED DISTURBANCE  
LIFTS NORTHEASTWARD INTO SE ILLINOIS. EXPECT INCREASING  
PRECIPITATION AT SOUTHERN TERMINALS KSPI-KDEC AROUND 10Z SPREADING  
NORTH TO KPIA-KBMI-KCMI AROUND 12Z. BY 14-16Z...PREDOMINANT RAIN  
WITH MVFR CIGS/VSBYS LIKELY AND INCLUDED IN TAFS. ISOLATED  
THUNDERSTORMS POSSIBLE AS WELL...BUT LIKELIHOOD/TIMING NOT HIGH  
ENOUGH FOR EXPLICIT MENTION THIS FAR OUT. BRIEFLY IMPROVING  
CONDITIONS LATE AFTERNOON EARLY EVENING AS FIRST DISTURBANCE MOVES  
OUT OF CENTRAL IL...BUT TRAILING WAVE/COLD FRONT EXPECTED TO  
INITIATE ADDITIONAL SHOWERS/THUNDERSTORMS TOWARD 06Z. WITH A  
NARROW WINDOW OF UNCERTAIN IMPROVEMENT...KEPT MVFR CIGS/VSBYS  
THROUGH 06Z. WINDS E-NE5-10 KTS THROUGH 15Z BECOMING VARIABLE-  
NNW DURING AFTERNOON AS LOW LIFTS TO THE NE OF CENTRAL IL AREA.  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...BARNES  
LONG TERM...BARNES  
AVIATION...ONTON  
 
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