063
FXUS63 KILX 200531
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1231 AM CDT SAT JUN 20 2026
KEY MESSAGES
- WIDESPREAD RAIN WILL OCCUR ACROSS CENTRAL ILLINOIS ON SUNDAY.
THE LATEST NBM INDICATES AN 80-90% CHANCE OF GREATER THAN 1
INCH...WITH A 40-50% CHANCE OF MORE THAN 3 INCHES IN THE
ILLINOIS RIVER VALLEY.
- THERE IS A SLIGHT RISK (LEVEL 2 OF 5) FOR SEVERE WEATHER ALONG
AND SOUTH OF A JACKSONVILLE TO CHARLESTON LINE ON SUNDAY.
DISCUSSION
ISSUED AT 158 PM CDT FRI JUN 19 2026
*** HEAVY RAINFALL ON SUNDAY ***
A VIGOROUS SHORT-WAVE TROUGH EVIDENT ON 18Z/1PM WATER VAPOR OVER
WESTERN BRITISH COLUMBIA WILL DIG SOUTHEASTWARD INTO THE
NORTHERN ROCKIES...HELPING EJECT A SEPARATE WAVE SPINNING OFF
THE COAST OF NORTHERN CALIFORNIA EASTWARD OVER THE NEXT 24-48
HOURS. AS THE CALIFORNIA WAVE CROSSES THE ROCKIES INTO THE
PLAINS, A LARGE CLUSTER OF CONVECTION WILL FORM ACROSS
NEBRASKA/KANSAS SATURDAY AFTERNOON/EVENING...THEN WILL PUSH
EASTWARD INTO CENTRAL ILLINOIS LATE SATURDAY NIGHT INTO SUNDAY.
WITH A 40-50KT 850MB JET STREAK ORIENTED FROM OKLAHOMA
NORTHEASTWARD INTO CENTRAL ILLINOIS AHEAD OF THE APPROACHING
WAVE, COPIOUS ATMOSPHERIC MOISTURE WILL BE ADVECTED INTO THE
REGION AS PRECIPITABLE WATER VALUES INCREASE TO 2.00-2.50. GIVEN
STRONG FORCING AND A STEADY SUPPLY OF MOISTURE, WIDESPREAD
RAINFALL IS EXPECTED ACROSS ALL OF CENTRAL AND SOUTHEAST
ILLINOIS. AS HAS BEEN PREVIOUSLY NOTED, THE EXACT PLACEMENT OF
THE HEAVIEST RAINFALL AXIS IS STILL SOMEWHAT IN QUESTION: HOWEVER,
THE 12Z JUN 19 SYNOPTIC MODELS HAVE ALL GENERALLY NUDGED IT
SLIGHTLY SOUTHWARD FROM PREVIOUS RUNS. WPC HAS SHIFTED THE
HEAVIEST BAND FROM A PEORIA TO PONTIAC LINE SOUTHWARD TO ALONG
THE I-72 CORRIDOR ACCORDINGLY. MEANWHILE THE 12Z NBM SHOWS A
HIGH PROBABILITY (80-90% CHANCE) OF GREATER THAN 1 INCH ACROSS
THE BOARD...WITH A 40-50% CHANCE OF MORE THAN 3 INCHES FOCUSED
IN THE ILLINOIS RIVER VALLEY. IF CURRENT TRENDS PERSIST, THINK
THE NBM WILL SHIFT ITS HIGHEST PROBABILITIES A BIT SOUTHWARD AS
WELL. AS IT STANDS NOW, THINK A BROAD SWATH OF 1.50 TO 2.50 WILL
OCCUR...WITH A BAND OF POTENTIALLY HIGHER AMOUNTS ALONG/NEAR
THE I-72 CORRIDOR. SINCE THE SOIL IS SATURATED AND WATER IS
STILL STANDING IN SEVERAL AREA FIELDS, RAINFALL OF THIS
MAGNITUDE WILL LEAD TO STEEP RISES ON CREEKS AND STREAMS AND
CREATE POCKETS OF FLASH FLOODING. AS A RESULT, A FLOOD WATCH
WILL BE CAREFULLY CONSIDERED WITH UPCOMING FORECAST UPDATES.
*** SEVERE WEATHER POTENTIAL ON SUNDAY ***
THE STORM PREDICTION CENTER (SPC) HAS ADDED A SLIGHT RISK (LEVEL
2 OF 5) FOR SEVERE ALONG/SOUTH OF A JACKSONVILLE TO CHARLESTON
LINE FOR SUNDAY. MODEL SOLUTIONS STILL EXHIBIT A GOOD DEAL OF
VARIABILITY: HOWEVER, THE OVERALL TREND HAS BEEN TO SHIFT THE
TRACK OF THE SURFACE LOW FURTHER SOUTH EITHER ACROSS THE HEART
OF CENTRAL ILLINOIS OR ALONG THE I-70 CORRIDOR. THE 12Z NAM IS A
NOTABLE OUTLIER, FEATURING A FURTHER NORTH TRACK AND A MUCH
DEEPER LOW. IF THIS PARTICULAR SCENARIO PANS OUT, CENTRAL
ILLINOIS COULD BE IN STORE FOR ANOTHER ROUND OF SIGNIFICANT
SEVERE WEATHER. WILL CONTINUE TO MONITOR FUTURE RUNS, BUT FOR
NOW WILL SIDE WITH THE GFS/ECMWF CONSENSUS. AN MCS WILL TRACK
ACROSS CENTRAL ILLINOIS SUNDAY MORNING THROUGH MID-AFTERNOON,
RESULTING IN HEAVY RAINFALL AND POTENTIAL FLOODING CONCERNS.
THIS SYSTEM WILL LEAVE BEHIND AN OUTFLOW BOUNDARY THAT WILL
SERVE AS THE FOCUS FOR STRONG TO SEVERE CONVECTION DURING THE
LATE AFTERNOON AND EVENING. GIVEN THE SOUTHWARD LOW TRACK TREND,
IT APPEARS THE MOST LIKELY LOCATION FOR THE BOUNDARY AND THE
SUBSEQUENT SEVERE RISK WILL FOCUS ACROSS CENTRAL/SOUTHERN
MISSOURI INTO THE OHIO RIVER VALLEY. THIS COULD STILL
POTENTIALLY IMPACT THE SOUTHERN KILX CWA WITHIN THE SLIGHT RISK
AREA, BUT THE MOST LIKELY SCENARIO WOULD BE FURTHER SOUTH ACROSS
THE OZARKS INTO FAR SOUTHERN ILLINOIS AND WESTERN KENTUCKY WHERE
A STRONGLY UNSTABLE (SBCAPES 2500-3500J/KG) AND MODERATELY
SHEARED (0-6KM SHEAR 30-40KT) ENVIRONMENT WILL EXIST. STAY TUNED
TO LATER FORECASTS FOR ADDITIONAL DETAILS.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1231 AM CDT SAT JUN 20 2026
SCATTERED -SHRA LOOK TO DEVELOP OVERNIGHT ALONG A WEAK FRONTAL
BOUNDARY NEAR KSPI-KDEC-KCMI, AND HAVE INCLUDED PROB30 FOR -SHRA
FROM 09Z-13Z AS A RESULT. NEVERTHELESS, VFR CONDITIONS ARE
EXPECTED TO CONTINUE WITH MINIMAL CHANCES FOR ANY MVFR
CIGS/VSBYS IN THIS AREA. WINDS LIGHT AND VARIABLE, BECOMING WNW
7-11 KTS BEHIND THE FRONTAL BOUNDARY BY AROUND 16Z. WINDS
DECREASING TO LIGHT AND VARIABLE AGAIN AFTER 00Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...BARNES
DISCUSSION...BARNES
AVIATION...37
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