821
FXUS63 KILX 212041
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
341 PM CDT SUN JUN 21 2026
KEY MESSAGES
- A TORNADO WATCH IS IN EFFECT FOR LOCATIONS ALONG AND SOUTH OF
A SHELBYVILLE TO PARIS LINE THROUGH 9PM THIS EVENING.
- BELOW NORMAL TEMPERATURES WILL PERSIST THROUGH THE WEEK
BEFORE A MARKED WARMING TREND PUSHES READINGS WELL INTO THE
80S CLOSE TO 90 DEGREES BY NEXT WEEKEND.
DISCUSSION
ISSUED AT 341 PM CDT SUN JUN 21 2026
*** TORNADO WATCH ***
20Z/3PM RADAR IMAGERY SHOWS A BAND OF RAIN WITH EMBEDDED
THUNDERSTORMS PUSHING ACROSS CENTRAL ILLINOIS. THE PRE-STORM
ENVIRONMENT REMAINS STABLE ACROSS A LARGE PORTION OF THE AREA:
HOWEVER, MLCAPES HAVE INCREASED TO 500-1000J/KG SOUTH OF A WARM
FRONTAL BOUNDARY DRAPED ALONG THE I-70 CORRIDOR. WITH SURFACE
DEWPOINTS IN THE UPPER 60S/LOWER 70S IN THE WARM SECTOR, RAP
SUGGESTS FURTHER DESTABILIZATION OVER THE NEXT 3-4 HOURS AS
MLCAPES REACH 1000-1500J/KG. DEEP-LAYER SHEAR IS CURRENTLY BEING
AUGMENTED BY AN APPROACHING MCV, WHILE 0-1KM SHEAR HAS INCREASED
TO 20-25KT NEAR THE BOUNDARY. AS A RESULT, THE SOUTHERN PART OF
THE RAIN BAND NOW CONTAINS ROTATING SUPERCELLS CAPABLE OF
PRODUCING TORNADOES AND DAMAGING WIND GUSTS. A TORNADO WATCH HAS
SUBSEQUENTLY BEEN ISSUED FOR LOCATIONS ALONG/SOUTH OF A
SHELBYVILLE TO PARIS LINE THROUGH 9PM. BASED ON RADAR TRENDS AND
LATEST HRRR/RAP DATA, IT APPEARS THE PRIMARY STORM RISK WILL
PUSH INTO INDIANA BY 6-7PM. MEANWHILE FURTHER WEST, WILL HAVE TO
KEEP AN EYE ON A BROKEN LINE OF MUCH WEAKER CELLS CURRENTLY
FIRING ALONG A QUINCY TO KANSAS CITY LINE. THESE STORMS ARE IN A
MUCH MORE UNFAVORABLE ENVIRONMENT AND ARE NOT EXPECTED TO
BECOME SEVERE: HOWEVER, GUSTY WINDS WILL STILL BE POSSIBLE INTO
THE EVENING AS THEY SPREAD E/SE INTO CENTRAL ILLINOIS...MAINLY
ALONG/SOUTH OF THE I-72 CORRIDOR.
*** QUIET MID-WEEK ***
COOL/DRY WEATHER WILL SETTLE INTO THE REGION FOR MONDAY AND
TUESDAY WITH DAYTIME HIGHS WELL BELOW NORMAL FOR THIS TIME OF
YEAR IN THE 70S AND OVERNIGHT LOWS DIPPING INTO THE 50S. GIVEN
PERSISTENT UPPER TROUGHING OVER CANADA, NORTHWESTERLY FLOW WILL
CONTINUE FOR THE REST OF THE WEEK. THE NEXT EMBEDDED SHORT-WAVE
TROUGH AND ACCOMPANYING COLD FRONT WILL PUSH THROUGH CENTRAL
ILLINOIS ON WEDNESDAY. WHILE DEEP-LAYER MOISTURE WILL BE
LACKING, THERE WILL BE STRONG ENOUGH FORCING TO WARRANT LOW
CHANCE POPS (30-40%) FOR SHOWERS/THUNDER, ESPECIALLY DURING THE
AFTERNOON AND EVENING.
*** WEEKEND WARM-UP AND STORM RISK ***
THE MID-WEEK FRONTAL BOUNDARY IS PROGGED TO STALL ACROSS THE
OHIO RIVER VALLEY ON THURSDAY, THEN BEGIN LIFTING SLOWLY BACK
NORTHWARD BY THE WEEKEND AS UPPER HEIGHTS RISE IN RESPONSE TO AN
UPSTREAM TROUGH DIGGING WEST OF THE ROCKIES. WHILE THE EXACT
SPEED OF THIS PROCESS IS STILL IN QUESTION, MODEL CONSENSUS
INDICATES THE MOST FAVORABLE PERIOD FOR RAIN WILL BE FROM LATE
FRIDAY THROUGH LATE SATURDAY WHEN SEVERAL BOUTS OF CONVECTION
MAY DEVELOP ALONG/NORTH OF THE FRONT. IT IS STILL TOO EARLY TO
DISCUSS ANY SPECIFIC SEVERE WEATHER RISKS: HOWEVER, ALL MACHINE
LEARNING ALGORITHMS SHOW LOW PROBABILITIES (LESS THAN 15% CHANCE)
FOR SEVERE. ONCE THE BOUNDARY LIFTS INTO THE GREAT LAKES, A
RETURN TO MORE TYPICAL SUMMERTIME WEATHER IS ANTICIPATED FOR
EARLY NEXT WEEK. IN FACT, THE 12Z NBM SHOWS A 30-50% CHANCE FOR
TEMPERATURES CLIMBING ABOVE 90 DEGREES BY NEXT SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1218 PM CDT SUN JUN 21 2026
SHOWERS AND A FEW THUNDERSTORMS ARE OVERSPREADING CENTRAL
ILLINOIS EARLY THIS AFTERNOON WITH ADDITIONAL DEVELOPMENT
POSSIBLE BEHIND THIS INITIAL LINE. CONFIDENCE IN DETAILS ON
COVERAGE/LOCATION OF LATE AFTERNOON/EVENING STORMS REMAINS LOW,
THUS PRECLUDES MORE THAN A PROB30 MENTION AT THIS TIME.
MEANWHILE, E/ESE WINDS CURRENTLY IN PLACE ARE EXPECTED TO BACK
TO NE BY LATE THIS EVENING AS WEAK LOW PRESSURE MOVES ACROSS THE
REGION. MVFR AND EVENTUALLY IFR CEILINGS WILL ACCOMPANY THE LOW
PASSAGE, WITH SLOW IMPROVEMENT EXPECTED FROM THE NORTHWEST
BEHIND THE DEPARTING WAVE MONDAY.
ILX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 1 AM CDT MONDAY FOR ILZ038-042>046-048>057-
061>063-066>068-071>073.
KEY MESSAGES...BARNES
DISCUSSION...BARNES
AVIATION...DEUBELBEISS
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