990
FXUS63 KILX 222323
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
623 PM CDT WED JUL 22 2026
KEY MESSAGES
- BELOW NORMAL TEMPERATURES THROUGH FRIDAY, WITH SOME LIGHT SHOWERS
FRIDAY AND FRIDAY NIGHT SW OF A BEARDSTOWN TO SHELBYVILLE
LINE.
- DANGEROUS HEAT ON SUNDAY AND MONDAY, WITH PEAK HEAT INDICES
OF 105-110 DEGREES IN SOME LOCATIONS.
- STORM CHANCES RETURN SUNDAY THROUGH TUESDAY, WITH A FAVORABLE
PATTERN FOR STRONG-TO-SEVERE STORMS. EXTENDED-RANGE ML
GUIDANCE DEPICTS DAILY 5-15% PROBABILITIES FOR SEVERE WEATHER-
MOST PROMINENT ON SUNDAY AND MONDAY.
- PLEASANT CONDITIONS SETTLE BACK INTO THE AREA BY THE MIDDLE
OF NEXT WEEK, FOLLOWING A COLD FRONTAL PASSAGE.
DISCUSSION
ISSUED AT 213 PM CDT WED JUL 22 2026
**UNSEASONABLY COOL WEATHER & LIGHT RAIN CHANCES (THROUGH
FRIDAY NIGHT)**
TODAY, A 1020 MB SFC ANTICYCLONE CONTINUES TO SLIDE IN FROM THE
NORTHWEST, BRINGING COOLER & DRIER AIR, LIGHTER SURFACE WINDS,
AND MAINLY CLEAR SKIES (WITH THE EXCEPTION OF SOME DIURNAL CU
AND THIN CIRRUS). DAILY HIGH TEMPERATURES IN THE MID-UPPER 70S
(8-10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR) AND MORNING
LOWS IN THE MID-UPPER 50S WILL PERSIST THROUGH FRIDAY. DEWPOINTS
REMAINING IN THE 50S WILL ALSO MAKE FOR COMFORTABLE HUMIDITY
LEVELS. THIS HIGH PRESSURE SYSTEM WILL DOMINATE THE MIDWEST AND
LOWER GREAT LAKES REGION BEFORE TRANSLATING EAST INTO THE MID-
ATLANTIC BY THE WEEKEND.
A MID-LEVEL SHORTWAVE TRAVERSING THE CENTRAL PLAINS ON FRIDAY
WILL PROMOTE FORCING FOR A BROAD SHIELD OF RAIN SHOWERS
EXTENDING INTO THE MID-MISSISSIPPI RIVER VALLEY THROUGH THE
EVENING. GIVEN PWATS OF 2 INCHES CLIPPING THE SOUTHWEST PORTION
OF THE CWA, WPC HAS INTRODUCED A MARGINAL (5-15%) CHANCE OF
EXCESSIVE RAINFALL, MAINLY SOUTH AND WEST OF A BEARDSTOWN TO
SHELBYVILLE LINE, WHERE POPS ARE HIGHEST (30-50% RANGE) LATE
FRIDAY. FORECAST SOUNDINGS SUGGEST THE LOW-LEVEL AIR MASS WILL
REMAIN DRY ENOUGH FOR MUCH OF THIS ACTIVITY TO BECOME VIRGA,
THOUGH ENOUGH TOP-DOWN SATURATION WILL LIKELY OCCUR FOR SOME
SHOWERS TO PRODUCE RAINFALL. THE ECMWF SUITE HAS BEEN AN OUTLIER
IN DEPICTING A FURTHER NORTHEAST TRACK OF THE DISTURBANCE,
RESULTING IN MORE NOTABLE RAINFALL AMOUNTS ACROSS THE AREA. FOR
NOW, NBM HAS UP TO ONE-QUARTER INCH OF RAIN IN OUR SOUTHWESTERN
COUNTIES.
**DANGEROUS HEAT (SUNDAY AND MONDAY)**
AS THE SFC RIDGE PUSHES EAST OF ILLINOIS BY THE EARLY WEEKEND,
SOUTHERLY LOW-LEVEL FLOW WILL RETURN, PROMPTING THE TRANSPORT OF
WARMER TEMPERATURES AND HIGHER DEWPOINTS BACK INTO THE AREA.
SEASONABLE TEMPS AND HUMIDITY ON SATURDAY QUICKLY TRANSITION
INTO DANGEROUS HEAT BY SUNDAY. AFTERNOON HIGHS IN THE LOW-TO-MID
90S COMBINED WITH DEWPOINTS IN THE MID-70S WILL PUSH HEAT
INDICES INTO THE 105-110 DEGREE RANGE IN SOME LOCATIONS,
ESPECIALLY WEST OF I-55, WHERE LREF PROBABILITIES OF REACHING
HEAT ADVISORY CRITERIA ARE 30-40%. NIGHTTIME LOWS LOOK TO ONLY
DIP INTO THE MID-TO-UPPER 70S, OFFERING LITTLE RELIEF THROUGH
TUESDAY AM. HOWEVER, CANNOT RULE OUT ANY SCATTERED STORM
CLUSTERS PUTTING A DAMPER IN PEAK HEATING FOR SOME AREAS ON BOTH
DAYS, THOUGH THE LOCATION AND TIMING OF THIS IS DIFFICULT TO
OUTLINE AT THIS RANGE.
**STORM CHANCES RETURN...SOME STRONG-TO-SEVERE (SUNDAY THROUGH
TUESDAY)**
THE POLEWARD ADVECTION OF RICH GULF MOISTURE THROUGH THE
WEEKEND WILL BEGIN TO INTRODUCE PLENTIFUL FUEL (MLCAPE UP TO
3000-4000 J/KG) FOR THUNDERSTORMS BACK TO THE MIDWEST. A RATHER
PERSISTENT SYNOPTIC PATTERN, CONSISTING OF A MID-LEVEL RIDGE
CENTERED NEAR THE FRONT RANGE, AND A LONGWAVE TROUGH FROM
ONTARIO INTO THE EAST COAST, PLACES THE REGION UNDER A 45-65 KT
BELT OF NORTHWESTERLY MID-LEVEL FLOW THROUGH NEXT WEEK.
RESULTING 0-6 KM BULK SHEAR OF 30-45 KTS WILL BE FAVORABLE FOR
THE ORGANIZATION OF ANY STORMS THAT OCCUR. FORCING IS NEBULOUS
ON SATURDAY, GIVEN THE JET CORE IS POSITIONED WELL NORTH AND
THERE ARE NO NOTABLE EMBEDDED SHORTWAVES TO SPEAK OF IN THE
AREA. STILL, CANNOT RULE OUT AN ISOLATED STORM, MAINLY TOWARDS
NORTHERN IL. THE MAIN FOCUS SHIFTS TO SUNDAY THROUGH TUESDAY, AS
A SERIES OF CONVECTIVELY-AUGMENTED SHORTWAVES MAY TRAVERSE THE
RIDGE AND PROVIDE ENOUGH FORCING FOR STRONG-TO-SEVERE
THUNDERSTORM CLUSTERS IN THE MIDWEST, SOME OF WHICH MAY HAVE THE
TENDENCY TO DIVE SOUTHWARD INTO OUR AREA. PWATS OF 1.8-2.0
INCHES AND ANY TRAINING STORMS MAY YIELD LOCALIZED FLOODING AS
WELL. THE EXTENT AND EVOLUTION OF THIS ACTIVITY WILL DEPEND UPON
HOW UPSTREAM CONVECTION PLAYS OUT EACH PRECEDING DAY.
THOUGH THE SPC DOES NOT YET HAVE ANY SEVERE WEATHER OUTLINES
FOR THIS PERIOD, EXTENDED-RANGE ML GUIDANCE IS CONSISTENT IN
HIGHLIGHTING CENTRAL ILLINOIS IN DAILY 5-15% CHANCES FOR SEVERE
THUNDERSTORMS. AT THIS RANGE, UNCERTAINTY IS TOO HIGH IN EXACT
PLACEMENT AND TIMING, SO WILL HAVE TO MONITOR HOW FORCING
MECHANISMS IRON OUT IN THE GUIDANCE IN THE COMING DAYS.
**PLEASANT WEATHER (MIDDLE OF NEXT WEEK)**
DURING THE EARLY-MIDDLE PART OF NEXT WEEK, A STRONGER COLD
FRONT IS LIKELY TO SWEEP THROUGH THE AREA, USHERING IN PLEASANT
WEATHER AND HIGH PRESSURE THEREAFTER. MODELS ARE IN SOME
DISAGREEMENT ON THE TIMING OF THIS FRONTAL PASSAGE, GIVEN THE
SERIES OF MID-LEVEL WAVES TRAVERSING THE RIDGE, THOUGH FROPA
SHOULD BE ON TUESDAY. IF THE FRONT ENDS UP FASTER THAN DEPICTED,
THE AFOREMENTIONED CHANCE OF STRONG STORMS ON TUESDAY COULD BE
SHUNTED SOUTH OF THE CWA.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 623 PM CDT WED JUL 22 2026
HIGH PRESSURE CURRENTLY OVER THE UPPER MIDWEST WILL GRADUALLY
MOVE SOUTHEAST OVER THE UPCOMING 24 HOURS TOWARD THE SOUTHERN
GREAT LAKES. CONDITIONS WILL REMAIN VFR, ALTHOUGH PERIODS OF
HIGH CLOUDS AND SCATTERED DIURNAL CUMULUS CAN BE EXPECTED. WINDS
N-NE 4-8 KTS THIS EVENING, BECOMING LIGHT AND VARIABLE TO E
AROUND 5 KTS BY 04Z. WINDS BECOMING E-SE 5-10 KTS AFTER 13Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...DEUBELBEISS
DISCUSSION...DEUBELBEISS
AVIATION...37
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