191
FXUS63 KILX 022311
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
611 PM CDT WED SEP 2 2026
KEY MESSAGES
- EXTREME HEAT: AN EXTREME HEAT WARNING IS IN EFFECT THROUGH
FRIDAY AS HIGH HEAT AND HUMIDITY PUSH PEAK HEAT INDEX VALUES
TO AROUND 105F. HIGHS MAY EXCEED 100F (40% TO 80% CHANCE)
SOUTH OF A SPRINGFIELD TO CASEY LINE THROUGH FRIDAY, WITH HEAT
INDICES LINGERING NEAR 100F INTO SATURDAY.
- ISOLATED SEVERE STORM POTENTIAL: WHILE DRY CONDITIONS
DOMINATE, THERE IS A LOW RISK (UNDER 20% CHANCE) FOR ISOLATED
POP-UP AFTERNOON OR EVENING THUNDERSTORM THURSDAY AND FRIDAY.
ANY STORM THAT DEVELOP COULD BECOME SEVERE WITH LOCALIZED
STRONG WINDS OR HAIL.
DISCUSSION
ISSUED AT 142 PM CDT WED SEP 2 2026
LATE SUMMER HEAT WAVE
UPPER-LEVEL RIDGING REMAINS DOMINANT ACROSS THE MIDWEST,
ANCHORED BY A ROBUST 596 DAM 500MB HIGH CENTERED OVER THE MID-
MISSISSIPPI AND TENNESSEE VALLEYS. THIS RIDGE AXIS IS PROJECTED
TO SHIFT TOWARD THE SOUTHEASTERN CONUS BY LATE WEEK. GUIDANCE
CONTINUES TO ADVERTISE 850MB THERMAL RIDGE TEMPERATURES OF
23-26C OVER THE REGION THROUGH SATURDAY, WELL ABOVE THE 90TH
PERCENTILE, FOLLOWING THIS MORNING'S 12Z SOUNDING OF 22C.
SURFACE TEMPERATURES WILL RUN WELL ABOVE NORMAL THROUGH THE
WEEKEND. DEW POINTS ARE EXPECTED TO PERSIST IN THE UPPER 60S TO
LOWER 70S, THOUGH DEEP MIXING INTO A DRIER COLUMN AND A SEASONAL
DROP IN EVAPOTRANSPIRATION WILL HELP KEEP THEM SOMEWHAT IN
CHECK. EVEN SO, TEMPERATURES HAVE A SOLID CHANCE OF REACHING
TRIPLE DIGITS. NBM PROBABILITIES FOR HITTING 100 DEGREES ARE
HIGHEST (40-80%) TODAY ALONG AND SOUTH OF A SPRINGFIELD TO CASEY
LINE, LOWERING SLIGHTLY TO 30-60% ACROSS THE SOUTHWESTERN CWA
THURSDAY AND FRIDAY. PEAK HEAT INDICES WILL GENERALLY RANGE NEAR
105 DEGREES THROUGH FRIDAY AND AROUND 100 DEGREES SATURDAY. DUE
TO THE PROLONGED PERIOD OF OPPRESSIVE CONDITIONS, THE HEAT
ADVISORY HAS BEEN UPGRADED TO AN EXTREME HEAT WARNING THROUGH
FRIDAY.
CONVECTIVE RISK & STORM POTENTIAL
PRECIPITATION CHANCES WILL STAY MOSTLY CONFINED TO NORTHERN
ILLINOIS AND THE GREAT LAKES NEAR THE JET STREAM THROUGH THE
REMAINDER OF THE WEEK. WITH SURFACE TEMPERATURES APPROACHING
CONVECTIVE THRESHOLDS DAILY, AN ISOLATED POP-UP AFTERNOON OR
EVENING THUNDERSTORM CANNOT BE COMPLETELY RULED OUT, THOUGH
OVERALL PROBABILITY REMAINS UNDER 20% DUE TO NEBULOUS AND WEAK
SYNOPTIC FORCING. MODELS LIKE THE RRFS CONTINUE TO HIGHLIGHT
THIS POP-UP POTENTIAL. ANY STORMS THAT MANAGE TO DEVELOP ON
THURSDAY WOULD BE SUPPORTED BY MLCAPE OF 2000-2500 J/KG AND
DEEP-LAYER SHEAR OF 25-30 KT. MLCAPE INCREASES TO 2500-3000 J/KG
ON FRIDAY, BUT NOTICEABLY WEAKER SHEAR POINTS TOWARD A MORE
PULSE-SEVERE MODE.
WEEKEND PATTERN SHIFT
LATE THIS WEEK INTO THE WEEKEND, A CLOSED UPPER LOW NEAR HUDSON
BAY WILL DIG TOWARD NEW ENGLAND, DEEPENING A LONGWAVE TROUGH
OVER THE EASTERN U.S. THIS PUSHES THE UPPER RIDGE AXIS WEST OVER
THE CENTRAL PLAINS AND PLACES CENTRAL ILLINOIS IN A NORTHWEST
FLOW REGIME. MEANWHILE, CANADIAN HIGH PRESSURE OVER QUEBEC WILL
PUSH A BACKDOOR COLD FRONT SOUTH INTO ILLINOIS, PROVIDING A
FOCUS FOR WEEKEND RAIN CHANCES (20-30%). TEMPERATURES WILL
GRADUALLY COOL FROM THE 90S AHEAD OF THE BOUNDARY DOWN INTO THE
LOWER-TO-MID 80S BEHIND IT. BECAUSE THIS TRANSITION UNFOLDS
SLOWLY, A THERMAL GRADIENT ACROSS CENTRAL ILLINOIS WILL PERSIST
INTO THE FIRST HALF OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 611 PM CDT WED SEP 2 2026
VFR CONDITIONS WILL CONTINUE THE NEXT 24 HOURS AS WE REMAIN UNDER A
LARGE AREA OF HIGH PRESSURE CENTERED OVER THE SOUTHEAST US.
SOUTHERLY WINDS WILL BE LIGHT OVERNIGHT THEN VEER TO THE SOUTHWEST
BY LATE MORNING WITH SPEEDS INCREASING TO AROUND 10-12 KTS.
ISOLATED THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON, BUT
CHANCES APPEAR LOW (20%).
CLIMATE
ISSUED AT 440 PM CDT MON AUG 31 2026
RECORD HIGH TEMPERATURES THIS WEEK:
LOCATION TUE 9/1 WED 9/2 THU 9/3 FRI 9/4
======== ======== ======== ======== ========
BLOOMINGTON... 102/1894 101/2011 102/1913 100/1925
CHAMPAIGN..... 102/2011 101/2011 99/2011 100/1954
CHARLESTON.... 99/2011 103/1953 100/1925 98/1925
DANVILLE...... 101/1953 101/1953 99/1913 101/1954
DECATUR....... 102/1953 102/1953 102/1913 103/1913
JACKSONVILLE.. 103/1913 103/2011 101/2011 103/1899
LINCOLN....... 102/1953 101/1953 100/1913 102/1954
OLNEY......... 105/1953 106/1953 105/1925 103/1954
PARIS......... 101/1953 102/1953 101/1913 104/1954
PEORIA........ 101/1913 100/1913 99/1913 98/2015
SPRINGFIELD... 102/2011 101/2011 100/2011 100/1954
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING UNTIL 7 PM CDT FRIDAY FOR ILZ027>031-
036>038-040>057-061>063-066>068-071>073.
KEY MESSAGES...DEUBELBEISS
DISCUSSION...DEUBELBEISS
AVIATION...NMA
CLIMATE...07/GEELHART
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