130
FXUS63 KILX 201710
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1210 PM 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 /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1208 PM CDT MON JUL 20 2026
A COLD FRONT WILL SWEEP ACROSS CENTRAL ILLINOIS TONIGHT. A
CLUSTER OF STORMS IS ONGOING AHEAD OF THE FRONT EARLY THIS
AFTERNOON ACROSS EASTERN IA/NORTHWEST IL. IT IS EXPECTED TO
TO DECAY AS IT OUTRUNS THE BETTER INSTABILITY TO THE WEST, BUT
A FEW SHOWERS OR STORMS MAY FESTER INTO PORTIONS OF CENTRAL
ILLINOIS. CONFIDENCE IS HIGHEST AT PIA AND SPI WHERE A PROB30
COVERS THIS THREAT. STORMS WILL REDEVELOP ALONG THE COLD FRONT
OVER PORTIONS OF THE UPPER MIDWEST LATE THIS AFTERNOON AND
EVENING AND ARE EXPECTED TO PUSH SOUTH ACROSS CENTRAL ILLINOIS
OVERNIGHT. WINDS AHEAD OF THE FRONT WILL BE OUT OF THE SW AND
WILL VEER TO WEST THEN NORTHWEST WITH PASSAGE OF THE FRONT.
FINALLY, SMOKE OVER THE REGION CONTINUES TO REDUCE VISIBILITY
THIS AFTERNOON INTO THE 3-5SM RANGE, BUT DO ANTICIPATE
VISIBILITY TO IMPROVE OVER THE NEXT FEW HOURS AND SW WINDS
INCREASE.
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...DEUBELBEISS
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