695
FXUS63 KILX 251940
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
240 PM CDT SAT JUL 25 2026
KEY MESSAGES
- OPPRESSIVE HEAT AND HUMIDITY RETURN SUNDAY AND MONDAY WITH
HEAT INDICES PEAKING BETWEEN 100 AND 110 DEGREES.
- SEVERE WEATHER PROBABILITIES INCREASE SUNDAY INTO MONDAY WITH
MONDAY PRESENTING THE MOST FAVORABLE CONVECTIVE WINDOW AHEAD
OF AN APPROACHING COLD FRONT.
DISCUSSION
ISSUED AT 240 PM CDT SAT JUL 25 2026
LINGERING CLOUD COVER HAS HELD TEMPERATURES DOWN SEVERAL DEGREES SO
FAR TODAY WITH 2 PM READINGS RANGING FROM THE LOW 70S TO NEAR 80
DEGREES. CLOUDS WILL SLOWLY ERODE FROM WEST TO EAST THROUGH EARLY
EVENING, THOUGH TEMPERATURES HAVE BEEN FURTHER REDUCED WITH HIGHS
THROUGH THE REMAINDER OF TODAY PEAKING IN THE LOW 80S IN WESTERN IL
AND MIDDLE TO UPPER 70S IN EASTERN IL. AFTER A BRIEF BREAK FROM THE
LOW CLOUDS THIS EVENING, STRONG WARM AIR ADVECTION AHEAD OF AN
APPROACHING WARM FRONT WILL BRING ANOTHER PERIOD OF LOW STRATUS
OVERNIGHT INTO SUNDAY MORNING AS MOISTURE GETS TRAPPED BENEATH A LOW-
LEVEL INVERSION. POCKETS OF LOWER VISIBILITY ARE ALSO POSSIBLE WITH
A LOW TO MEDIUM CHANCE (20-40%) FOR DENSE FOG.
MID-LEVEL HEIGHTS RISE HEADING INTO SUNDAY AS THE UPPER RIDGE
AMPLIFIES OVER THE WEST-CENTRAL US, SENDING 20-25C 850 MB
TEMPERATURES INTO THE MIDDLE MISSISSIPPI VALLEY. SURFACE
TEMPERATURES WILL SURGE INTO THE UPPER 80S TO LOW 90S ON SUNDAY, AND
THEN THE LOW TO MIDDLE 90S ON MONDAY. DEWPOINTS IN THE UPPER 70S TO
80 DEGREES WILL EQUATE TO HEAT INDICES OF 100 TO 110 DEGREES THE
NEXT TWO DAYS WITH MONDAY BEING THE HOTTEST. A HEAT ADVISORY REMAINS
IN EFFECT FOR COUNTIES WEST OF I-57 SUNDAY AFTERNOON THROUGH MONDAY
WHERE CONFIDENCE HAS REMAINED HIGHEST IN CRITERIA BEING MET (HEAT
INDEX 105 DEGREES). AN EXPANSION EASTWARD MAY BE NEEDED FOR SOME ON
MONDAY.
ONE COMPLICATING FACTOR TO THE HEAT IS CONVECTION AND CLOUD COVER.
CENTRAL ILLINOIS IS POSITIONED ON THE EASTERN PERIPHERY OF THE UPPER
RIDGE, MAKING US A PRIME TARGET FOR NORTHWEST FLOW/SHORTWAVE TROUGH
ACTIVITY. OUR FIRST OPPORTUNITY COMES DURING THE DAY ON SUNDAY
IF THE WAVE IS STRONG ENOUGH TO OVERCOME OUR CAPPING INVERSION.
ADDITIONAL OPPORTUNITIES EXIST SUNDAY NIGHT THROUGH MONDAY NIGHT
AS A COUPLE MORE SHORTWAVES AND AN APPROACHING COLD FRONT SERVE
AS OUR FORCING MECHANISMS. HOWEVER, PLACEMENT AND TIMING OF
ACTIVITY REMAINS HIGHLY UNCERTAIN WITH CAMS PROVIDING LITTLE
HELP. ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL TO
BECOME SEVERE AS THEY MOVE THROUGH AN ENVIRONMENT CHARACTERIZED
BY STRONG INSTABILITY (3500+ J/KG SBCAPE) AND SUFFICIENT
VERTICAL WIND SHEAR (~30 KTS). HAZARDS WITH ANY SEVERE STORMS
WOULD BE DAMAGING WINDS, LARGE HAIL, AND HEAVY RAINFALL.
TEMPERATURES AND DEWPOINTS DROP CLOSER TO SEASONAL NORMALS FOR THE
MIDDLE TO END OF THE WEEK BEHIND A COLD FRONT. NORTHWEST FLOW
REMAINS POSITIONED ALOFT THROUGH THE UPCOMING WEEK AND MAY OPEN THE
DOOR FOR OCCASIONAL PRECIPITATION OPPORTUNITIES THROUGH NEXT
WEEKEND. HOWEVER, DETAILS REMAIN UNCERTAIN.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1241 PM CDT SAT JUL 25 2026
IFR TO MVFR CEILINGS WILL SLOWLY IMPROVE FROM WEST TO EAST THROUGH
EARLY EVENING. AFTER A BRIEF PERIOD OF VFR CONDITIONS THIS EVENING,
CLOUDS WILL EXPAND AND LOWER ONCE AGAIN AS MOISTURE RAPIDLY ADVECTS
NORTHWARD AHEAD OF AN APPROACHING WARM FRONT. THE LATEST NEAR TERM
GUIDANCE SHOWS MVFR TO IFR CEILINGS/VISBYS DEVELOPING OVERNIGHT AND
LINGERING INTO SUNDAY MORNING AT MOST AIRFIELDS. CEILINGS SHOULD
IMPROVE BY LATE MORNING/EARLY AFTERNOON. ISOLATED SHOWERS AND STORMS
(20% CHANCE) ARE POSSIBLE IN WEST-CENTRAL IL LATE SUNDAY MORNING,
BUT CONFIDENCE IN PLACEMENT AND COVERAGE REMAINS FAR TOO LOW TO
MENTION AT KPIA.
ILX WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY FROM NOON SUNDAY TO 9 PM CDT MONDAY FOR
ILZ027>031-036>038-040>044-047>054-061.
KEY MESSAGES...NMA
DISCUSSION...NMA
AVIATION...NMA
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