927
FXUS63 KILX 281711
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1211 PM CDT FRI AUG 28 2026
KEY MESSAGES
- QUIET AND SEASONABLE WEATHER PERSISTS THIS WEEKEND.
- A LATE SEASON HEAT WAVE IS FORECAST TO IMPACT THE AREA NEXT
WEEK. DAILY HEAT INDICES ARE PROJECTED TO REACH AS HIGH AS
100-105 DEGREES MONDAY THROUGH FRIDAY.
- PRECIPITATION CHANCES ARE LOW FOR THE NEXT SEVERAL DAYS,
THOUGH AN ACTIVE STORM TRACK IS FORECAST JUST TO OUR NORTH
FOR MUCH OF NEXT WEEK.
DISCUSSION
ISSUED AT 1211 PM CDT FRI AUG 28 2026
SURFACE HIGH PRESSURE STRETCHED FROM THE EASTERN GREAT LAKES
SOUTHWEST THROUGH CENTRAL IL, CONTINUES TO PROVIDE LIGHT WINDS
AND MODEST TEMPERATURES AND HUMIDITY FOR LATE AUGUST. THESE
TRENDS WILL CONTINUE TONIGHT WITH LOWS DROPPING TO THE LOWER
60S.
LATER TONIGHT AND SATURDAY, SHORTWAVE ENERGY TRAVERSES THE
UPPER MIDWEST. CONVECTIVE ALLOWING MODELS SHOW A CLUSTER OF
STORMS TRACKING SOUTHEAST ACROSS IA SATURDAY MORNING,
DISSIPATING AS IT REACHES THE MISSISSIPPI RIVER AND OUTRUNS
UPPER SUPPORT. THIS WILL LEAVE CENTRAL IL WITH INCREASING HIGH
AND MID LEVEL CLOUDS SATURDAY AFTERNOON. THERE IS A VERY LOW
CHANCE OF A FEW SPRINKLES REACHING THE GROUND FROM THE MID LEVEL
CLOUD DECK. TIGHTENING MSLP GRADIENT WILL BRING A MORE
SUSTAINED SOUTHERLY WIND FLOW THAN RECENT DAYS, WITH THE
POTENTIAL FOR A FEW GUSTS REACHING 15-20 MPH INTO MIDDAY BEFORE
THE INCREASING CLOUD COVER LIMITS MIXING. HIGHS WILL CLIMB A
FEW DEGREES TO THE MID/UPPER 80S.
WARM ADVECTION/ISENTROPIC LIFT ALOFT INCREASES SATURDAY NIGHT
AND SUNDAY MORNING. THE CURRENT BLENDED FORECAST REMAINS DRY,
BUT THIS IS A PERIOD WE'LL NEED TO WATCH FOR A FEW SCATTERED
SHOWERS AND STORMS, SHOULD TRENDS PERSIST.
HIGH CONFIDENCE REMAINS IN A LATE-SEASON THERMAL RIDGE
AMPLIFYING ACROSS THE MID-MISSISSIPPI VALLEY FOR MUCH OF NEXT
WEEK. DETERMINISTIC AND ENSEMBLE GUIDANCE ALIGN ON 500 MB
HEIGHTS SWELLING TO 594-596 DAM, WITH 850 MB TEMPERATURES
RANGING BETWEEN +22C AND +24C. EXTREME FORECAST INDEX (EFI)
VALUES FROM THE ECMWF RANGE BETWEEN 0.80 AND 0.85 FOR MAX
TEMPERATURES MONDAY THROUGH WEDNESDAY. THIS CONFIRMS THAT THE
AIRMASS APPROACHES THE TOP OF CLIMATOLOGY FOR LATE AUGUST AND
EARLY SEPTEMBER. THAT SAID, A FEW FACTORS WILL WORK TO MITIGATE
THE HEAT IMPACTS THIS TIME AROUND. (1) SOUTHWEST GRADIENT FLOW
DOMINATES THE PERIOD, LEADING TO 10-15 MPH WINDS AND HIGHER
DAYTIME GUSTS. (2) DEWPOINTS ARE NOT PROGGED TO BE EXCESSIVELY
HIGH, MAINLY MID 60S TO AROUND 70F, OWING TO LOWER ET AT THIS
POINT IN THE GROWING SEASON. (3) LOWER SUN ANGLE THAN A MONTH OR
TWO AGO. GRIDDED HEAT INDEX FORECASTS PEAK AT 100-105 MON- FRI.
LOWER CONFIDENCE EXTENDS TO PRECIP CHANCES NEXT WEEK. AN ACTIVE
RING OF FIRE PATTERN WILL LIKELY BRING REPEATED MCSS ON THE
PERIPHERY OF THE RIDGE, WHICH MODELS HANDLE POORLY 3+ DAYS OUT.
MOST GUIDANCE KEEPS THIS ACTIVITY TO OUR NORTH UNTIL LATE WEEK,
WHEN THE RIDGE BEGINS TO BREAK DOWN, ALLOWING A FRONT TO SAG IN
FROM THE NORTH. SHEAR IS PROJECTED TO BE RELATIVELY WEAK THROUGH
THE PERIOD, LEADING TO ML/AI SEVERE OUTLOOK PROBABILITIES IN
THE 5% CATEGORY NEAR THE BOUNDARY.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1211 PM CDT FRI AUG 28 2026
VFR THROUGH THE FORECAST. LIGHT/VARIABLE WINDS THROUGH TONIGHT
WILL FIRM FROM THE S/SSE NEAR 10 KT BY LATE MORNING AS HIGH
PRESSURE SHIFTS OFF TO OUR EAST.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...25
DISCUSSION...25
AVIATION...25
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