480  
FXUS63 KILX 260418  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
1118 PM CDT SUN OCT 25 2020  
   
SYNOPSIS
 
 
ISSUED AT 753 PM CDT SUN OCT 25 2020  
 
RAIN AND SNOW WILL MOVE INTO PORTIONS OF CENTRAL ILLINOIS  
OVERNIGHT, WITH BETTER CHANCES OF MORE WIDESPREAD RAIN COMING  
DURING THE LATE MORNING INTO THE EVENING. EXPECT PRECIPITATION TO  
LINGER THROUGH MONDAY NIGHT SOUTH OF I-70. AFTER A COUPLE DRY  
DAYS, ANOTHER ROUND OF RAIN IS EXPECTED WEDNESDAY NIGHT INTO  
THURSDAY.  
 

 
   
UPDATE
 
 
ISSUED AT 753 PM CDT SUN OCT 25 2020  
 
A FEW AREAS OF LIGHT RAIN/DRIZZLE HAVE BEEN TRACKING NORTHEAST  
NEAR AND EAST OF I-57 THIS EVENING, WITH JUST A COUPLE SPOTS  
RECEIVING MEASURABLE RAIN. MAIN FEATURE REMAINS THE AREA OF  
RAIN/SNOW ADVANCING EAST ACROSS IOWA. LATEST HRRR SUGGESTS AN  
ARRIVAL AROUND MIDNIGHT NEAR GALESBURG, WITH SOME EXPANSION  
SOUTHWEST ALONG THE ILLINOIS RIVER VALLEY AS THE NIGHT PROGRESSES.  
FORECAST SOUNDINGS INDICATE POTENTIAL FOR A COMPLETE SWITCHOVER  
NEAR GALESBURG FOR A COUPLE HOURS AROUND SUNRISE, WITH MORE OF A  
RAIN/SNOW MIX ACROSS THE ILLINOIS RIVER VALLEY.  
 
MEANWHILE, PRECIPITATION EXPECTED TO QUICKLY SPREAD NORTHEAST  
FROM KANSAS EARLY MONDAY MORNING. SOME OF THE GUIDANCE INDICATES  
PERHAPS A QUICKER ARRIVAL OF THIS LATTER PRECIPITATION, SO POP'S  
WERE INCREASED SOME ACROSS THE SOUTHWEST CWA DURING THE MORNING.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH MONDAY)  
ISSUED AT 331 PM CDT SUN OCT 25 2020  
 
CLOUDS CONTINUE TO INHIBIT MUCH IN TERMS OF TEMPERATURE  
ACCELERATION. THESE CLOUDS ARE ASSOCIATED WITH AN ADVANCING  
LARGE-SCALE WEATHER SYSTEM THAT WILL MOVE OVER THE MIDWEST THROUGH  
THE FIRST HALF OF THE WEEK. WATCHING RADAR THIS AFTERNOON, SOME  
LIGHT RETURNS HAVE DEVELOPED ACROSS THE SOUTHEASTERN CWA, DUE TO  
THE BAROCLINIC FRONTAL ZONE. THESE LIGHT SPRINKLES WILL BE  
POSSIBLE THROUGH THE EVENING, BEFORE DISSIPATING AFTER SUNSET.  
 
THE MAIN SYSTEM WILL CONTINUE TO APPROACH THE MIDWEST OVERNIGHT,  
WITH TEMPERATURES AGAIN DROPPING TO THE 30S AND 40S. AS THE  
SLIGHTLY TILTED UPPER LEVEL SHIFTS SOUTHWARD, THIS WILL MOVE THE  
CURRENT RADAR RETURNS ACROSS THE UPPER MIDWEST TO THE SOUTH.  
HEADING INTO EARLY MONDAY MORNING, TEMPS WILL BE NEAR FREEZING  
ALONG AND NORTHWEST OF THE ILLINOIS RIVER VALLEY, ALLOWING FOR THE  
DEVELOPMENT OF SNOW IN THE LOWER ATMOSPHERE. AT THIS TIME, WITH  
THE WARM SFC LAYER, NOT EXPECTING ANY FREEZING RAIN...LIMITING  
ALL PRECIP TO SNOWFALL OR RAIN. AS TEMPERATURES BEGIN TO WARM  
THROUGH THE MORNING, SHOULD SEE THE WINTRY MIX CHANGE TO ALL  
RAINFALL FROM NW TO SE. DURING THE AFTERNOON, A WEAK WAVE WILL  
SLIDE THROUGH THE SOUTHERN HALF OF ILLINOIS, ENHANCING RAINFALL  
CHANCES ACROSS THE SOUTHERN CWA. THIS WILL BE AIDED BY UPPER LEVEL  
HIGH PRESSURE OFF THE SE COAST OF THE US, LIFTING ADDITIONAL  
MOISTURE TO THE REGION. AS WITH PAST MODEL RUNS, THE TOTAL AMOUNT  
OF PRECIPITATION REMAINS MAXED OUT NEAR 0.50 INCHES ALONG THE I-70  
CORRIDOR. FURTHER SOUTH, ACROSS PAH/LSX CWA, AMOUNTS RANGE UPWARDS  
OF 1 INCH.  
 

 
   
LONG TERM
 
(MONDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 331 PM CDT SUN OCT 25 2020  
 
HEADING THROUGH MONDAY NIGHT, THE UPPER LEVEL SPLIT LOWS WILL  
WORK SOUTH AND EAST, ALLOWING FOR PRECIPITATION TO BEGIN ENDING  
FROM NW TO SE. THIS WILL SLOWLY WORK THROUGH THE REGION OVERNIGHT  
INTO TUESDAY, WHEN THE SYSTEM WILL LOSE MOISTURE FEEDING.  
 
NOW INTRODUCE ANOTHER TROPICAL SYSTEM BREWING IN THE GULF OF  
MEXICO, ALONG WITH THE CUT-OFF LOW FROM THE DESERT SW THAT WAS  
ASSOCIATED WITH THE SYSTEM THAT ARRIVES TONIGHT. AS THE LOW  
ADVANCES EASTWARD THROUGH THE FAR SOUTHERN PLAINS, IT WILL BE HELD  
BACK BY THE APPROACHING TROPICAL SYSTEM MID-WEEK. ONCE THE  
TROPICAL SYSTEM MOVES ONSHORE, THE SFC LOW WILL BE DIRECTED  
NORTHEAST, AS THE TROPICAL REMNANTS MAINTAIN CONTROL OF THE SFC  
WEATHER PATTERN. THIS WILL MOVE INTO THE OHIO RIVER VALLEY REGION  
DURING THE EARLY PART OF THURSDAY. CURRENT MODELS HAVE UPDATED TO  
BRING THE RAINFALL ON THE BACKSIDE OF THE SYSTEM, ALONG WITH  
REMAINING MOISTURE FROM THE CUT-OFF LOW THROUGH THE CENTRAL AND  
SOUTHERN ILLINOIS AREA. IF THIS HOLDS, WIDESPREAD RAINFALL WILL BE  
LIKELY THROUGHOUT THURSDAY, BEFORE ANOTHER STRETCH OF DRY WEATHER  
AND HIGH PRESSURE TAKES HOLD AND DOMINATES THROUGH THE WEEKEND.  
 
MODELS APPEAR QUIET FROM ABOUT FRIDAY THROUGH SUNDAY, WITH THE  
POSSIBILITY OF CONTINUED QUIET WEATHER INTO THE NEXT WEEK...BUT  
WITH MODEL PREDICTIONS THAT FAR OUT, THINGS ARE LIKELY TO CHANGE.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)  
ISSUED AT 1118 PM CDT SUN OCT 25 2020  
 
MOSTLY MVFR CEILINGS PREVAILING OVER THE TAF SITES LATE THIS  
EVENING, WITH SOME BRIEF LIFTS ABOVE 3,000 FEET NEAR KPIA. GENERAL  
TREND WILL BE FOR CEILINGS TO GRADUALLY FALL BELOW 2,000 FEET  
THOUGH, WHICH ISN'T REALLY EXPECTED TO IMPROVE UNTIL MONDAY  
EVENING AROUND KPIA/KBMI. INITIAL WAVE OF RAIN AND POTENTIALLY  
SOME MIXED PRECIP WILL PASS NEAR/NORTH OF KPIA/KBMI THROUGH EARLY  
MORNING. MORE DOMINANT AREA OF RAIN WILL SURGE NORTHEAST OUT OF  
MISSOURI AND ACROSS THE KSPI-KCMI CORRIDOR MID TO LATE MORNING,  
AND PERSIST INTO EARLY EVENING. THIS LATTER RAIN MAY LOWER  
VISIBILITIES TO A FEW MILES AT TIMES, MOST LIKELY MIDDAY OR EARLY  
AFTERNOON.  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...GEELHART  
SYNOPSIS...GEELHART  
SHORT TERM...BAKER  
LONG TERM...BAKER  
AVIATION...GEELHART  
 
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