953
FXUS63 KILX 211048
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
548 AM CDT TUE JUL 21 2026
KEY MESSAGES
- SEVERE WEATHER THREAT: A LOW RISK (20% TO 30% CHANCE) FOR
STRONG TO SEVERE THUNDERSTORMS EXISTS EARLY THIS AFTERNOON
ACROSS EAST-CENTRAL AND SOUTHEAST ILLINOIS. HIGH-INTENSITY
UPDRAFTS COULD GENERATE LOCALIZED DAMAGING WIND GUSTS, ALONG
WITH LOCALLY HEAVY RAINFALL.
- AIR QUALITY: AIR QUALITY AND VISIBILITY ARE EXPECTED TO
IMPROVE SIGNIFICANTLY TODAY ACROSS THE AREA AS A COLD FRONT
MOVES THROUGH AND PUSHES WILDFIRE SMOKE OUT OF THE REGION.
- DRIER & COOLER MIDWEEK: DRIER AND SLIGHTLY COOLER CONDITIONS
ARRIVE WEDNESDAY THROUGH FRIDAY, WITH HIGH TEMPERATURES IN THE
MID TO UPPER 70S AND MINIMAL RAIN CHANCES.
DISCUSSION
ISSUED AT 258 AM CDT TUE JUL 21 2026
SYNOPTIC OVERVIEW AND SEVERE CONVECTIVE POTENTIAL...
THE WARM FRONT HAS ADVANCED EAST OF ILLINOIS PUTTING OUR CWA SOLIDLY
IN THE WARM SECTOR. LAST EVENINGS STORMS HAVE DISSIPATED WITH A
LINGERING CLUSTER OF STORMS IN N MO SLIDING SOUTHEAST TOWARD ST
LOUIS. A PREFRONTAL LINE OF SHOWERS HAS DEVELOPED FROM CHICAGO
TO THE QUAD CITIES AS OF 230 AM CDT THIS MORNING, WHICH SIGNALS
THE SYNOPTIC LIFT HAS COMMENCED WELL AHEAD OF THE COLD FRONT.
PARAMETER SPACE IN TODAYS WARM SECTOR LOOKS TO DESTABILIZE TO
2800 MLCAPE VALUES ALONG WITH BULK SHEAR VALUES UP TO 35 KT.
THERE ARE DIFFERING SOLUTIONS AMONG THE CAMS AS TO TIMING AND
LOCATION OF CONVECTIVE INITIATION IN OUR EASTERN AND
SOUTHEASTERN COUNTIES, BUT THE CONSENSUS SHOWS EARLY AFTERNOON
STORMS SHOULD DEVELOP EAST OF ILLINOIS AND POSSIBLY BACKBUILD TO
IMPACT AREAS EAST OF I-57. SPC HAS A CORRIDOR OF MARGINAL RISK
WITH A SMALL SECTION OF SLIGHT RISK FOR OUR FAR 3 SE COUNTIES.
AT THIS POINT, CONFIDENCE IS LOW THAT STORMS WILL HAVE MUCH
IMPACT IN ILLINOIS. HOWEVER, WITH DCAPE VALUES UP TO 1400 J/KG,
ANY UPDRAFT THAT INTENSIFIES WILL BE ABLE TO TAP INTO PWATS OF
1.8 G/KG TO INCREASE PRECIP LOADING AND SUBSEQUENT DOWNDRAFTS.
HAVE 30-50 POPS IN SE IL THIS MORNING INTO EARLY AFTERNOON, WITH
CHANCES DROPPING OFF QUICKLY AFTER 2 PM IN SE IL.
SMOKY CONDITIONS ARE PROJECTED TO IMPROVE SIGNIFICANTLY TODAY, AS
THE COLD FRONT PUSHES ACROSS IL. AN EVENTUAL TRANSITION BACK TO
HIGH PRESSURE LATER THIS WEEK COULD SET THE STAGE FOR ANOTHER
ROUND OF SMOKE TO BE BLOWN INTO THE MIDWEST, BUT FOR NOW WE
SHOULD BE ABLE TO ENJOY IMPROVED AIR QUALITY TODAY.
EXTENDED OUTLOOK...
FOR THE REMAINDER OF THE WORK WEEK, BEGINNING WEDNESDAY,
CONDITIONS WILL TREND DRIER AND SLIGHTLY COOLER. SPRAWLING
CANADIAN HIGH-PRESSURE WILL SPREAD SOUTHEAST ACROSS THE MIDWEST,
KEEPING HIGH TEMPERATURES IN THE MID TO UPPER 70S WEDNESDAY
THROUGH FRIDAY, WITH NO MEASURABLE PRECIPITATION THROUGH
THURSDAY. BY THURSDAY NIGHT, A SIGNAL FOR WARM ADVECTION-DRIVEN
CONVECTION DEVELOPS TO OUR WEST, RESULTING IN A 20-30% CHANCE OF
STORMS ON FRIDAY WEST OF FULTON CO TO SHELBY CO. A WARMING
TREND WILL COMMENCE NEXT WEEKEND AS THE SURFACE RIDGE AXIS
SHIFTS TO OUR EAST, ALLOWING FOR A RETURN OF WARMER SOUTHERLY
FLOW.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 548 AM CDT TUE JUL 21 2026
FOR THE MOST PART, VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES
NEXT 24HRS. HOWEVER, SOME LIGHT SMOKE IS REDUCING VISIBILITY IN
CHAMPAIGN TO MVFR 5SM FOR AN HOUR OR SO AT THE START OF THE 12Z
TAF PERIOD. A COLD FRONT IS POISED TO MOVE ACROSS CENTRAL
ILLINOIS FROM THE WEST THIS MORNING, TRIGGERING ISOLATED SHOWERS
AND STORMS. CLOUD CEILINGS SHOULD BE VFR, EXCEPT FOR MVFR
BRIEFLY IF A STORM IMPACTS A TERMINAL SITE DIRECTLY. THE CHANCES
OF A DIRECT IMPACT ARE 20% OR LESS. THOSE STORM CHANCES SHOULD
PUSH EAST OF THE TAF SITES BY 17Z, BRINGING A WIND SHIFT FROM W-SW
TO NW. SOME GUSTS TO 15-25KT ARE EXPECTED BEHIND THE FRONT
DURING THE DAY, BEFORE WEAKENING DURING THE EVENING. ADDITIONAL
CU IS EXPECTED BEHIND THE FRONT DURING THE MORNING AND AFTERNOON
HOURS WITH HIGH CIRRUS CONTINUING, BUT NO ADDITIONAL MVFR
CEILINGS ARE EXPECTED.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...SHIMON
DISCUSSION...SHIMON
AVIATION...AUTEN/SHIMON
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