864
FXUS63 KILX 271918
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
218 PM CDT MON JUL 27 2026
KEY MESSAGES
- OPPRESSIVE HEAT AND HUMIDITY CONTINUES THROUGH EARLY EVENING
WITH HEAT INDICES PEAKING BETWEEN 105 AND 115 DEGREES.
- MULTIPLE THUNDERSTORM COMPLEXES WILL MOVE ACROSS IL THIS
AFTERNOON/EVENING, PRESENTING A CONDITIONAL THREAT FOR SEVERE
WEATHER. DAMAGING WINDS (60-70+ MPH GUSTS) AND HEAVY RAINS
ARE A RISK ESPECIALLY IN EASTERN AND SOUTHEASTERN IL THIS
AFTERNOON AND EARLY EVENING.
- A COLD FRONT WILL BRING RELIEF FROM THE HIGH HEAT AND HUMIDITY ON
TUESDAY, TRANSITIONING US BACK TO NEAR NORMAL TEMPERATURES
AND HUMIDITY LEVELS DURING MID WEEK.
DISCUSSION
ISSUED AT 218 PM CDT MON JUL 27 2026
OUTSIDE OF THE STORM RISK TODAY, IT HAS BEEN VERY HOT AND HUMID
TODAY. HEAT INDICES HAVE BEEN AROUND 100-105 SO FAR BUT STILL HAVE
TIME TO INCREASE TO ABOUT 115 DEGREES IN SOME SPOTS. THE EXTREME
HEAT WARNING CONTINUES UNTIL TONIGHT AT 9 PM. IF THUNDERSTORMS
MATERIALIZE AND MOVE IN DURING THE AFTERNOON AND EARLY EVENING, IT
WOULD COOL TEMPS/HEAT INDICES AND WOULD LIKELY END THE HEAT
HEADLINES EARLIER THAN 9 PM. BEYOND TODAY, TEMPERATURES BECOME MORE
SEASONABLE AND LESS HUMID WITH HIGHS IN THE 80S AND LOWS IN THE 60S
THROUGH NEXT WEEK.
TODAY'S FORECAST HAS BEEN A DOOZY. THE MODELS HAVEN'T BEEN OF THE
GREATEST ASSISTANCE RECENTLY WITH THIS ROUND OF CONVECTION. WE HAVE
AN ENHANCED RISK (LEVEL 3 OF 5) FOR AREAS NEAR AND NORTH OF A HENRY
TO MARSHALL LINE AND A SLIGHT RISK (LEVEL 2 OF 5) ELSEWHERE FOR
TODAY. PRIMARILY THIS RISK IS FOR DAMAGING WINDS, POTENTIALLY
STRONGER THAN 70 MPH, BUT THERE IS ALSO A 2% TORNADO RISK FOR THE
AREA WITHIN THE ENHANCED RISK.
OUR 12Z SOUNDING SHOWS MUCAPE OVER 5500 J/KG, EFFECTIVE SHEAR OF ~50
KNOTS, AND PWATS OF NEARLY 2 INCHES. A SHORTWAVE IS PULSING THROUGH
THIS AFTERNOON ACROSS ILLINOIS AND INDIANA, BASED OFF GFS 500 MB
VORTICITY. THE STORMS CURRENTLY OVER THE CHICAGO-LAND AREA MAY CLIP
EASTERN IL AS IT DROPS SOUTH INTO INDIANA AND THEY ARE EVOLVING INTO
A DAMAGING WIND THREAT AS IT TRANSITIONS TO A LINEAR MODE RATHER
THAN SUPERCELLULAR. IT IS STARTING TO TREND TOWARDS AREAS WEST OF I-
55 MAY NOT SEE ANY OF THE SEVERE THREAT TODAY. THERE MAY BE SOME
SHOWERS/STORMS THAT DIRECTION BUT IT LOOKS LIKE THE MAIN SHOW WILL
REMAIN EAST OF I-55 THIS AFTERNOON/EVENING. AN ADDITIONAL WAVE MAY
MOVE BEHIND IT THAT WILL ALSO DROP SOUTH, POTENTIALLY RIDING THE
IL/IN BORDER, BUT COULD POSSIBLY BE WEAKER IN STRENGTH, BASED OFF
THE HRRR. THE HRRR'S 16Z AND 17Z RUNS ARE PICKING UP THE ACTIVE
CONVECTION WELL. THE STORMS SHOULD HAVE EXITED BY 10 PM TONIGHT.
STORMS WILL BE MOVING TO THE SOUTH-SOUTHEAST AT 30-40 MPH THIS
AFTERNOON/EVENING.
THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS COMES IN ON FRIDAY
INTO SATURDAY AS A SHORTWAVE MOVES THROUGH THE AREA.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1233 PM CDT MON JUL 27 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE 18Z PERIOD. THERE IS A
CHANCE FOR STRONG STORMS LATER THIS AFTERNOON INTO THE EVENING
HOURS. CONFIDENCE IN THE LOCATION AND TIMING OF THE STORMS IS
LOW SO OPTED FOR THE PROB30 GROUP FOR 21-01Z. HEAVY RAIN WILL BE
ACCOMPANYING ANY STORMS, SO LOWERED VISIBILITY IS POSSIBLE IF
THEY MOVE THROUGH. THE WINDS WILL BE VEERING THROUGHOUT THE
PERIOD, BECOMING NORTHERLY BY THE MORNING.
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.
KEY MESSAGES...COPPLE
DISCUSSION...COPPLE
AVIATION...COPPLE
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