692
FXUS63 KILX 271711
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1211 PM CDT THU AUG 27 2026
KEY MESSAGES
- COMFORTABLE AND DRY WEATHER IS ANTICIPATED THROUGH SATURDAY,
FOLLOWED BY THE RETURN OF HOT AND HUMID CONDITIONS EARLY NEXT
WEEK.
DISCUSSION
ISSUED AT 1211 PM CDT THU AUG 27 2026
HIGH PRESSURE STRETCHED NORTH TO SOUTH OVER THE EASTERN PLAINS
CONTINUES TO CONTROL REGIONAL WEATHER THROUGH FRIDAY. HRRR AND
RAP MODEL SOUNDINGS DISPLAY A COLUMN DOMINATED BY SUBSIDENCE AND
DRY LOW-LEVEL AIR, WITH SURFACE DEW POINTS HOLDING IN THE 60S.
TEMPERATURES REMAIN SEASONABLY MILD. HIGHS TODAY AND FRIDAY
REACH THE LOW-MID 80S UNDER MOSTLY SUNNY SKIES. SURFACE WINDS
WILL BE LIGHT THROUGH FRIDAY WITH THE RIDGE AXIS NEARBY. AS THE
HIGH SLIDES EAST TOWARD THE MID- ATLANTIC ON SATURDAY, LOW-
LEVEL FLOW TRANSITIONS TO THE SOUTH- SOUTHEAST, INITIATING WARM
AIR ADVECTION. AFTERNOON HIGHS ON SATURDAY WARM INTO THE MID
80S, WHILE OVERNIGHT LOWS DROP COMFORTABLY TO AROUND 60 THE NEXT
COUPLE NIGHTS.
A SYNOPTIC PATTERN SHIFT OCCURS SUNDAY INTO EARLY NEXT WEEK AS
AN EXPANSIVE 500 MB RIDGE AMPLIFIES OVER THE CENTRAL PLAINS AND
EXPANDS INTO THE MIDWEST. HIGH CONFIDENCE EXISTS REGARDING THE
SUBSTANTIAL TEMPERATURE SURGE, WHILE LOWER CONFIDENCE SURROUNDS
THE SOUTHERN EXTENT OF CONVECTIVE TRACKS RIDING THE RIDGE
PERIMETER.
NOTABLE MODEL DISAGREEMENTS EMERGE REGARDING RIDGE AMPLITUDE
AND STRUCTURE AS WE HEAD THROUGH THE EARLY TO MID PORTIONS OF
NEXT WEEK. MORE AMPLIFIED SOLUTIONS KEEP THE STORM TRACK TO OUR
NORTH, ANCHORING THE PRIMARY TRACK OF ACTIVE WEATHER ACROSS
MINNESOTA, WISCONSIN, AND FAR NORTHERN ILLINOIS. MEANWHILE,
MODEL SOLUTIONS FAVORING A FLATTER RIDGE WOULD BRING THE
SOUTHERN EDGE OF THE "RING OF FIRE" INTO PARTS OF CENTRAL IL.
THE FORECAST RELIES ON THE NBM, WHICH FAVORS THE AMPLIFIED
SOLUTION AND LOWER POPS, MAINLY AFFECTING THE FAR NORTHERN CWA
WITH SLIGHT CHANCE LEVELS (20% OR LESS) THROUGH MID NEXT WEEK.
THERMAL ADVECTION RAMPS UP UNDER THE RIDGE, WITH 850 MB
TEMPERATURES CLIMBING NEAR +25 C. NBM GUIDANCE PROJECTS HIGHS
REACHING THE LOWER 90S SUNDAY, THEN LOWER TO MID 90S MONDAY
THROUGH WEDNESDAY. ACCOMPANIED BY DEW POINTS IN THE UPPER 60S
TO LOWER 70S, PEAK HEAT INDEX VALUES RANGE BETWEEN 100-105 F.
CLIMATOLOGICALLY, THE ECMWF EXTREME FORECAST INDEX (EFI)
HIGHLIGHTS THIS HEAT WAVE WITH MAXIMUM TEMPERATURE EFI VALUES
BETWEEN 0.70 AND 0.85 ACROSS CENTRAL ILLINOIS FROM MONDAY
THROUGH WEDNESDAY, SIGNALING AN UNUSUALLY HOT AIRMASS FOR LATE
AUGUST TO EARLY SEPTEMBER. THE CLIMATE PREDICTION CENTER (CPC)
6-10 DAY OUTLOOK REINFORCES THIS TREND, LEANING HEAVILY TOWARD
ABOVE- NORMAL TEMPERATURES ACROSS THE REGION WITH A 70 TO 80
PERCENT PROBABILITY SEPT. 1-5.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1211 PM CDT THU AUG 27 2026
SCT-BKN DIURNAL CU AND NNW WINDS UNDER 10 KT WILL DOMINATE THE
AREA THIS AFTERNOON. WINDS GO CALM TO LIGHT/VARIABLE THIS
EVENING WITH SKC. PERIODS OF MVFR VISIBILITIES IN LIGHT FOG ARE
LIKELY EARLY FRIDAY MORNING, AND HAVE TEMPO GROUPS TO ACCOUNT
FOR THIS.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...25
DISCUSSION...25
AVIATION...25
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