813
FXUS63 KILX 150513
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1213 AM CDT TUE SEP 15 2026
KEY MESSAGES
- AFTER A BRIEF RESPITE, TEMPERATURES WILL AGAIN RUN WELL ABOVE
NORMAL THE REMAINDER OF THE WEEK. PER LREF ENSEMBLES, PROBABILITIES
OF HIGH TEMPERATURES ABOVE 95 DEGREES ARE GENERALLY 40-60% IN
AREAS SOUTH OF I-70 THROUGH THE UPCOMING WEEKEND.
- AN INCOMING COLD FRONT WILL STALL OVER CENTRAL ILLINOIS, WITH
PERIODS OF SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY.
THERE IS A LOW (5-15%) PROBABILITY OF DAMAGING WINDS WITH THE
STORMS TUESDAY AFTERNOON AND EVENING.
DISCUSSION
ISSUED AT 220 PM CDT MON SEP 14 2026
DEW POINT TEMPERATURES THIS AFTERNOON ARE ONLY IN THE MID 40S TO
LOWER 50S ACROSS THE FORECAST AREA. HOWEVER, AS SOUTHERLY WINDS
INCREASE OVERNIGHT, A FETCH OF GULF MOISTURE WILL BRING THEM UP
INTO THE MID 60S OVER WEST CENTRAL ILLINOIS BY DAYBREAK. AHEAD
OF THE INCOMING COLD FRONT, THIS JUICIER AIR MASS WILL
OVERSPREAD CENTRAL ILLINOIS ON TUESDAY. AS TEMPERATURES OVER
MUCH OF THE AREA REACH WELL INTO THE 90S, TRIPLE DIGIT HEAT
INDICES WILL RETURN TO AREAS NEAR AND SOUTH OF I-72. THERE
REMAINS A CONCERN WITH NEEDING A HEAT ADVISORY, BUT AT THE
PRESENT TIME, THE HIGHEST DEW POINTS WILL BE CLOSEST TO THE
FRONT, WHERE TEMPERATURES SHOULD ONLY REACH THE 80S. WITH THE
FRONT STALLING OVER CENTRAL ILLINOIS, HIGHS IN THE 90S WILL
CONTINUE SOUTH OF IT THE REMAINDER OF THE WEEK. ECMWF EXTREME
FORECAST INDEX IS NEAR THE TOP OF THE SCALE THROUGH THURSDAY.
TEMPERATURES MAY FALL JUST SHY OF RECORDS, BUT WILL BE CLOSE IN
SOME INSTANCES (SEE TABLE IN CLIMATE SECTION BELOW).
MIXED LAYER CAPE'S OVER THE FORECAST AREA ARE PROGGED TO REACH
2000-2500 J/KG ON TUESDAY, WITH DECENT 0-6KM SHEAR AROUND 30-40
KNOTS IMMEDIATELY ALONG THE FRONT. SEVERAL OF THE CAM'S ARE SHOWING
DEVELOPMENT NEAR THE I-72 CORRIDOR TOWARD MID TO LATE AFTERNOON,
THOUGH JUST SOUTH OF THE AXIS OF HIGHEST SHEAR. SPC DAY2
CONVECTIVE OUTLOOK HASN'T CHANGED TOO MUCH, STILL HIGHLIGHTING A
LEVEL 1 RISK OF SEVERE WEATHER OVER NEARLY THE ENTIRE FORECAST
AREA. PERIODS OF SHOWER/STORMS CONTINUE THROUGH MID WEEK, THOUGH
THEY WILL SHIFT NORTHWARD WITH TIME AS THE FRONT BEGINS TO LIFT
BACK NORTH.
AS WE GET INTO THE WEEKEND AND EARLY NEXT WEEK, PERSIST UPPER
LEVEL HIGH PRESSURE OVER THE LOWER MISSISSIPPI VALLEY SHOULD
FINALLY SHIFT EASTWARD, ALLOWING FOR SOME COOLER WEATHER TO
ARRIVE BY MONDAY. HOWEVER, THE INTERNATIONAL MODELS ARE
SUGGESTING RIDGING REDEVELOPING OVER THE PLAINS EARLY NEXT WEEK,
EDGING EASTWARD. WITH A WARMING TREND. CPC OUTLOOK FOR SEPTEMBER
20-24TH INDICATES A 50-60% CHANCE OF ABOVE NORMAL TEMPERATURES
TO START AUTUMN.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1213 AM CDT TUE SEP 15 2026
A WARM FRONT WILL LIFT THROUGH THE AREA OVERNIGHT, TURNING WINDS
FROM SOUTHEASTERLY TO SOUTHERLY. SIMULTANEOUSLY, A 40-45 KT LOW-
LEVEL JET IS NOTED JUST WEST OF THE AREA AND WILL BRING A
PERIOD OF LLWS AT KPIA AND KBMI THROUGH EARLY TUESDAY MORNING. A
COLD FRONT WILL APPROACH FROM THE WEST LATER IN THE DAY,
SPARKING THE DEVELOPMENT OF SCATTERED SHOWERS AND STORMS. PROB30
GROUPS ARE IN PLACE FROM 00-06Z WHICH IS WHEN THUNDERSTORM
POTENTIAL SEEMS MOST LIKELY. OUTSIDE OF ANY STORM ACTIVITY, VFR
CONDITIONS SHOULD PREVAIL.
CLIMATE
ISSUED AT 220 PM CDT MON SEP 14 2026
RECORD TEMPERATURES THE NEXT SEVERAL DAYS:
LOCATION TUE WED THU FRI SAT
======== ======== ======== ======= ======= =======
BLOOMINGTON 102/1939 98/1939 97/1927 97/1906 95/1948
CHAMPAIGN 98/1939 98/1939 94/2018 97/1893 94/1948
CHARLESTON 99/1939 98/1927 98/1927 97/1954 96/1925
DECATUR 101/1939 99/1939 97/1954 96/1983 97/1955
JACKSONVILLE 101/1939 97/1939 97/1927 95/1955 96/1925
OLNEY 104/1939 100/1927 99/1927 99/1953 98/1940
PEORIA 100/1939 94/1939 95/1927 93/1908 95/1948
SPRINGFIELD 100/1939 100/1939 95/1954 95/2018 95/1978
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...GEELHART
DISCUSSION...GEELHART
AVIATION...NMA
CLIMATE...GEELHART
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