396
FXUS63 KILX 200741
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
241 AM CDT MON JUL 20 2026
KEY MESSAGES
- IMPROVING AIR QUALITY: WILDFIRE SMOKE FROM CANADA WILL CAUSE HAZY
CONDITIONS AND REDUCED AIR QUALITY ACROSS CENTRAL ILLINOIS
TODAY. SOUTHERLY WINDS ARE EXPECTED TO CLEAR THE PLUME
NORTHEASTWARD BY THIS EVENING, BRINGING NOTICEABLE RELIEF.
- SEVERE STORMS TONIGHT: THERE REMAINS MODERATE CONFIDENCE FOR
A SEVERE WEATHER THREAT PRIMARILY AFTER MIDNIGHT TONIGHT. AN
ORGANIZED LINE OF STORMS IS EXPECTED TO MOVE SOUTHEASTWARD,
WITH A PRIMARY THREAT OF DAMAGING DOWNBURST WINDS.
- LINGERING STORM THREAT TUESDAY IN SOUTHEAST IL: A SLOWING
COLD FRONT KEEPS A LOWER CONFIDENCE THREAT OF STORMS IN
SOUTHEAST ILLINOIS THROUGH TUESDAY AFTERNOON. QUIETER, COOLER,
AND MORE COMFORTABLE WEATHER ARRIVES STATEWIDE BY WEDNESDAY.
DISCUSSION
ISSUED AT 240 AM CDT MON JUL 20 2026
SMOKE AND AIR QUALITY...
WILDFIRE SMOKE WILL LINGER FOR ANOTHER DAY ACROSS CENTRAL IL,
HOWEVER RELIEF IS ON THE HORIZON. A WARM FRONTAL BOUNDARY WILL
LIFT NORTHWARD THROUGH THE REGION TODAY, CAUSING A WIND SHIFT TO
THE S-SW. THIS TRANSITION WILL FACILITATE THE CLEARING OF THE
PLUME, PUSHING IT NORTHEASTWARD AND ALLOWING FOR IMPROVING AIR
QUALITY CONDITIONS ACROSS THE AREA BY THIS EVENING.
SEVERE WEATHER OUTLOOK: TODAY AND TONIGHT
SEVERAL CAMS ARE PROPAGATING THE ONGOING COMPLEX OF STORMS IN
WEST-CENTRAL MINNESOTA INTO OUR NW CWA BY EARLY AFTERNOON. THERE
IS SUPPORT FOR THAT SCENARIO AS BULK SHEAR VALUES CLIMB TOWARD
35KT THIS AFTERNOON. HOWEVER, THE CONSENSUS OF HIGH RESOLUTION
MODELS HAVE THAT COMPLEX DIMINISHING BEFORE REACHING THE IL
RIVER VALLEY. SO THE CHANCES OF SEVERE WEATHER WITH THAT INITIAL
STORM SYSTEM APPEAR LOW. THE PRIMARY FOCUS FOR SEVERE STORMS
WITH THE DAY 1 OUTLOOK WILL BE AFTER MIDNIGHT TONIGHT. FORECAST
SOUNDINGS INDICATE ROBUST DESTABILIZATION, WITH MLCAPE VALUES
PEAKING NEAR 2500 J/KG. THIS INSTABILITY WILL COINCIDE WITH A
POTENT JET STREAM IMPULSE DIGGING INTO THE UPPER MIDWEST,
DRIVING A SIGNIFICANT INCREASE IN DEEP-LAYER SHEAR. PROJECTIONS
OF 40-50KT OF 0-6KM BULK SHEAR SUGGEST A FAVORABLE ENVIRONMENT
FOR ORGANIZED CONVECTIVE SYSTEMS.
CONVECTIVE INITIATION IS ANTICIPATED OVER THE UPPER MIDWEST BY THIS
AFTERNOON, DRIVEN BY AN APPROACHING SHORTWAVE TROUGH. THE STORM
MODE SHOULD TRANSITION INTO A MORE ORGANIZED CLUSTER OR LINE AS
IT PROPAGATES SOUTHEASTWARD DURING THE MID-TO-LATE EVENING. A
STRENGTHENING LOW-LEVEL JET WILL BE CRITICAL IN SUSTAINING THIS
ACTIVITY AS IT TRAVERSES THE INSTABILITY GRADIENT ACROSS CENTRAL
ILLINOIS. GIVEN THE OVERLAP OF INSTABILITY AND SHEAR, THIS
PERIOD REMAINS THE PRIMARY WINDOW OF CONCERN FOR SEVERE
THUNDERSTORMS, AND WE WILL CONTINUE TO MONITOR THE MESOSCALE
EVOLUTION CLOSELY.
STORM CHANCES AND SEVERE POTENTIAL: TUESDAY
A SLOWING TREND IN THE COLD FRONTAL MOVEMENT WILL SET THE STAGE FOR
LINGERING SEVERE WEATHER POTENTIAL ON TUESDAY. THERE ARE
INDICATIONS OF A FLARE-UP OF STORMS IN THE POST FRONTAL AIRMASS
ACROSS SE IL, BUT HIGH UNCERTAINTY REMAINS ON COVERAGE OF THOSE
STORMS. A MORE LIMITED SHEAR AND INSTABILITY PROFILE THAN MONDAY
NIGHT SHOULD LIMIT SEVERE POTENTIAL SOMEWHAT. THAT COMPLEX OF
STORMS SHOULD PUSH SOUTHEAST OF OUR CWA BY LATE TUESDAY.
EXTENDED FORECAST: WEDNESDAY THROUGH THE WEEKEND
A WELCOME SHIFT TOWARD QUIETER, MORE SEASONAL WEATHER ARRIVES MID-
WEEK. BEGINNING WEDNESDAY, A SPRAWLING CANADIAN HIGH-PRESSURE
SYSTEM WILL SETTLE INTO THE MIDWEST, USHERING IN A DRIER AIRMASS
AND PROVIDING RELIEF FROM THE RECENT HEAT. EXPECT COMFORTABLE
TEMPERATURES TOPPING OUT IN THE LOW TO MID-80S, WITH A DRY
FORECAST PREVAILING THROUGH THE REMAINDER OF THE WORK WEEK. AS
THE SURFACE RIDGE AXIS DRIFTS TO OUR EAST NEXT WEEKEND, A
GRADUAL WARMING TREND WILL COMMENCE, BRINGING A RETURN OF WARMER
SOUTHERLY FLOW.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1223 AM CDT MON JUL 20 2026
SMOKE WILL CONTINUE TO BRING VIS ISSUES AT ALL SITES OVERNIGHT.
HOWEVER, AS WINDS INCREASE OUT OF THE SOUTHWEST LATE THIS
MORNING, THE SMOKE SHOULD BEGIN TO PUSH TO THE NORTHEAST AND
THIN OUT, RESULTING IN UNRESTRICTED VIS THE REMAINDER OF THE TAF
PERIOD. SOME SCATTERED MID CLOUDS WILL OCCUR THIS AFTERNOON WITH
A FEW CU, BUT THIS WILL DISSIPATE IN THE EVENING WITH SCATTERED
CIRRUS DURING THE EVENING. PRECIP LOOKS TO HOLD OFF UNTIL AFTER
06Z LATE TONIGHT SO NO MENTION OF PRECIP WITH THIS SET OF TAFS.
WINDS WILL BE LIGHT AND VARIABLE NOW BUT THEN INCREASE TO 10KTS
OF LESS OUT OF THE SOUTHWEST FOR THE AFTERNOON AND EVENING.
ILX WATCHES/WARNINGS/ADVISORIES
AIR QUALITY ALERT UNTIL MIDNIGHT CDT TONIGHT FOR ILZ027>031-
036>038-040>057-061>063-066>068-071>073.
KEY MESSAGES...SHIMON
DISCUSSION...SHIMON
AVIATION...AUTEN
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