163
FXUS63 KILX 011850
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
150 PM CDT SAT AUG 1 2026
KEY MESSAGES
- SPOTTY HEAVY RAINFALL THROUGH EARLY EVENING CREATES A
LOCALIZED FLASH FLOODING THREAT ACROSS EAST CENTRAL ILLINOIS.
- LOW-LEVEL HORIZONTAL SHEAR ALONG A TRAILING SURFACE TROUGH
FOSTERS BRIEF FUNNEL CLOUDS ACROSS EAST-CENTRAL ILLINOIS
THROUGH LATE AFTERNOON.
- A LATE WEEK WEATHER SYSTEM BRINGS THE NEXT CHANCE FOR SHOWERS
AND STORMS.
DISCUSSION
ISSUED AT 150 PM CDT SAT AUG 1 2026
A VERTICALLY STACKED/CLOSED LOW SLOWLY TRACKING EAST ACROSS
CENTRAL IL SERVES AS THE PRIMARY LIFTING MECHANISM FOR SHOWERS
AND ISOLATED THUNDERSTORMS INTO TONIGHT. LATEST ANALYSIS
DEPICTS A MOIST AIRMASS ANCHORED BENEATH THE LOW, WITH
PRECIPITABLE WATER (PWAT) VALUES AROUND 1.8 INCHES. THE NOSE OF
MODEST INSTABILITY (SURFACE-BASED CAPE NEAR 1000 J/KG) EXTENDS
AS FAR WEST AS THE IL/IN BORDER. WITHIN THE ZONE OF MAXIMIZED
ASCENT JUST NORTH AND EAST OF THE MID LEVEL LOW CENTER OVER EAST
CENTRAL IL, LOCALIZED RAINFALL RATES UP TO 2 INCHES PER HOUR
ARE POSSIBLE THROUGH EARLY EVENING. A FLASH FLOOD WATCH REMAINS
IN EFFECT FOR EAST CENTRAL IL THROUGH 06Z, WHERE LOCALIZED
TOTALS OF 2-5 INCHES HAVE BEEN SEEN IN RECENT HRRR GUIDANCE.
BENEATH THE LOW AND ALONG THE TRAILING SURFACE TROUGH AXIS IN
EAST- CENTRAL ILLINOIS, RAP AND HRRR BOUNDARY-LAYER PROFILES
SHOW ENHANCED LOW-LEVEL VORTICITY, STEEP 0-3 KM LAPSE RATES
WHERE CLOUD BREAKS HAVE DEVELOPED, AND MINIMAL DEEP-LAYER
SHEAR. THE NON-SUPERCELL TORNADO (NST) PARAMETER HIGHLIGHTS
VALUES OF 1 TO 2 ACROSS THIS AREA THROUGH 23Z. THESE CONDITIONS
FAVOR BRIEF, SHEAR-ZONE FUNNEL CLOUDS - SEE LATEST SPECIAL
WEATHER STATEMENT (SPS) FOR MORE INFO.
RAINFALL DIMINISHES FROM THE WEST TONIGHT AS THE CLOSED SHIFTS
EASTWARD. BEHIND THE LOW, MSLP GRADIENT TIGHTENS, AND WILL
PROMOTE 20-30 MPH WIND GUSTS FROM THE NORTH-NORTHEAST THROUGH
THIS EVENING. POST- FRONTAL LOW STRATUS AND PATCHY FOG ARE
LIKELY TO PERSIST THROUGH DAYBREAK SUNDAY. CAMS SHOW ISOLATED
INSTABILITY SHOWERS DEVELOPING OVER EASTERN IL SUNDAY AFTERNOON,
AND HAVE 20-30% POPS TO COVER THIS.
ENSEMBLE AND DETERMINISTIC MODEL SUITES ARE IN STRONG
AGREEMENT REGARDING TRANSIENT UPPER-LEVEL RIDGING ACROSS THE
MISSISSIPPI VALLEY MON-TUE. DRY WEATHER PREVAILS FOR THIS PERIOD
WITH NBM GUIDANCE INDICATING SEASONABLE HIGH TEMPERATURES IN
THE LOW-MID 80S.
FORECAST GUIDANCE CONTINUES TO SHOW A MID-LATITUDE SHORTWAVE
TROUGH DIGGING OUT OF THE NORTHERN PLAINS FOR THE LAST HALF OF
THE WEEK. NOTABLE MODEL DISAGREEMENTS EXIST REGARDING THE TRACK
AND INTENSITY OF THIS FEATURE, THOUGH THE CONSENSUS SHOW A FRONT
SLOWLY MOVING IN FROM THE NORTH, THEN POSSIBLY STALLING.
RESULTING CHANCE POPS FROM THE NBM EXTEND FROM WED-FRI.
GENERALLY WEAK SHEAR SHOULD LIMIT ORGANIZED SEVERE POTENTIAL,
WITH MANY ML/AI SEVERE OUTLOOK PRODUCTS HIGHLIGHTING AROUND A 5%
RISK FOR MUCH THE FRI-SAT PERIODS.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1222 PM CDT SAT AUG 1 2026
LOW PRESSURE WAS CENTERED NEAR KDEC AT 17Z. NORTH OF THE LOW,
WIDESPREAD SHOWERS AND IFR CEILINGS WERE PREVALENT AT KPIA-KBMI.
SOUTH/EAST OF THE LOW, SPOTTY SHOWERS AND SCT-BKN IFR STRATUS
WAS PREVALENT AT THE OTHER CENTRAL IL TERMINALS. AS THE LOW
TRACKS EAST THIS AFTERNOON, IFR CONDITIONS ARE EXPECTED TO
EXPAND OVER THE REMAINDER OF THE TERMINALS. SHRA WILL DIMINISH
FROM THE WEST LATE AFTERNOON TO EARLY EVENING, COINCIDENT WITH A
TIGHTENING PRESSURE GRADIENT ON THE BACK SIDE OF THE LOW. THIS
WILL RESULT IN N/NE GUSTS INCREASING TO 20-25 KT. THE GUSTS MAY
SUBSIDE FOR A TIME LATER TONIGHT, THEN RETURN AFTER SUNRISE. IFR
CEILINGS WILL BE PREVALENT INTO SUNDAY MORNING, WITH HIGHER
PROBABILITIES OF MVFR CEILINGS WEST OF I-55 BY LATE MORNING.
ILX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 1 AM CDT SUNDAY FOR ILZ045-046-055-057.
KEY MESSAGES...25
DISCUSSION...25
AVIATION...25
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