742
FXUS63 KILX 242339
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
639 PM CDT MON AUG 24 2026
KEY MESSAGES
- COMFORTABLE, LOW-IMPACT WEATHER PERSISTS THROUGH TUESDAY.
- THUNDERSTORM CHANCES (20-40%) RETURN WEDNESDAY EVENING, WITH
DAMAGING WINDS AND HAIL AS THE MAIN THREATS. FLASH FLOODING IS
NOT A RISK.
- PLEASANT AND DRY WEATHER IS ANTICIPATED FROM THURSDAY INTO
SATURDAY, FOLLOWED BY AN APPROACHING HEAT DOME EARLY NEXT WEEK
THAT COULD DRIVE HEAT INDEX VALUES UP TO 100 DEGREES.
DISCUSSION
ISSUED AT 1219 PM CDT MON AUG 24 2026
QUIET AND LOW-IMPACT WEATHER WILL PERSIST THROUGH TUESDAY UNDER
THE INFLUENCE OF A MID-LEVEL RIDGE AND BUILDING SURFACE HIGH
PRESSURE OVER THE GREAT LAKES REGION. TEMPERATURES WILL REMAIN
TYPICAL FOR LATE AUGUST, FEATURING AFTERNOON HIGHS IN THE LOW
80S. LOW RELATIVE HUMIDITY LEVELS WILL ALLOW OVERNIGHT LOWS TO
DROP INTO THE 50S, CREATING PLEASANT EVENING CONDITIONS.
A PATTERN SHIFT IS EXPECTED BY WEDNESDAY AS A WELL-DEFINED
SHORTWAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT TRACK OUT OF
THE CANADIAN PRAIRIES AND ACROSS THE GREAT LAKES. SOUTHERLY
SURFACE WINDS AHEAD OF THE ADVANCING FRONTAL BOUNDARY WILL DRIVE
WEDNESDAY AFTERNOON TEMPERATURES INTO THE MID-80S. MODERATE
INSTABILITY IS ANTICIPATED IN THE BOUNDARY LAYER, SUPPORTED BY A
NARROW PLUME OF LOW-70S DEWPOINTS POOLING AHEAD OF THE FRONT
THAT WILL HELP YIELD MLCAPE VALUES AROUND 2500 J/KG. OVERLAPPING
WITH APPROXIMATELY 30 KNOTS OF BULK SHEAR, THIS BUOYANCY WILL
FAVOR ORGANIZED SUPERCELLULAR STRUCTURES ALONG AND AHEAD OF THE
FRONT. FORECAST MESOSCALE SOUNDINGS FOR WEDNESDAY AFTERNOON
FEATURE STRAIGHT OR SUBTLE VEER-BACK-VEER HODOGRAPHS, INDICATING
PRIMARY THREATS OF HAIL AND DAMAGING WINDS OVER A TORNADO RISK.
HIGH-RESOLUTION CAM GUIDANCE SHOWS MIXED SIGNALS REGARDING
CONVECTIVE COVERAGE. THIS UNCERTAINTY STEMS FROM THE STRENGTH OF
SYNOPTIC FORCING OVER CENTRAL ILLINOIS, AS THE PRIMARY
SHORTWAVE DISPLACEMENT WELL TO THE NORTH MAY KEEP OVERALL
FORCING AND STORM COVERAGE LIMITED.
LIMITED MOISTURE RETURN AHEAD OF WEDNESDAY'S FRONT IS KEEPING
QPF DOWN. WITH FORECAST PWATS AROUND 1.5 INCHES, AND PROGRESSIVE
ATMOSPHERIC FLOW, THE FLASH FLOOD RISK FROM CONVECTIVE PRECIP
IS QUITE LOW.
FOLLOWING THE PASSAGE OF THE FRONT, DRY AND LESS HUMID
CONDITIONS WILL TAKE HOLD THURSDAY THROUGH SATURDAY AS AN
ELONGATED CENTRAL U.S. UPPER RIDGE PROMOTES THE GRADUAL BUILD OF
A CONTINENTAL POLAR (CP) AIRMASS ACROSS THE MIDWEST AND GREAT
LAKES. DAYTIME HIGHS WILL HOVER AROUND 80F, WITH OVERNIGHT LOWS
DIPPING INTO THE 50S FOR THE REMAINDER OF THE WORKWEEK.
BY EARLY NEXT WEEK, MEDIUM-RANGE GLOBAL ENSEMBLES INDICATE A
NOTABLE WARMING TREND AS A STRONG UPPER TROUGH MAKES LANDFALL IN
THE PACIFIC NORTHWEST, DRIVING THE RIDGE AXIS EASTWARD INTO THE
MIDWEST. THE COMBINED PRESENCE OF A 588-594 MB RIDGE CORE AND
WEAK LOW-LEVEL RETURN FLOW ON ITS WESTERN FLANK WILL HEIGHTEN
THE POTENTIAL FOR TRIPLE-DIGIT HEAT INDICES EARLY NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 639 PM CDT MON AUG 24 2026
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES NEXT 24HRS. SKIES
WILL BECOME CLEAR THIS EVENING AND CONTINUE INTO THE OVERNIGHT
HOURS. EXPECTING MORE CU TO DEVELOP AGAIN TOMORROW, BUT THINK IT
WILL BE FEW AND NOT SCT. WINDS WILL BE LIGHT AND VARIABLE
THROUGH THE PERIOD. LIGHT FOG IS POSSIBLE AT EACH SITE IN THE
MORNING, SO HAVE TEMPO GROUP AT ALL SITES FOR 5SM BR FROM
09-13Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...AUTEN
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