textproduct: Central Illinois

KEY MESSAGES

- Seasonal and mostly dry weather is expected the next few days.

- The next chance for showers and storms arrives midweek. Some of these storms could be strong to marginally severe.

DISCUSSION

Issued at 235 AM CDT Sun Aug 23 2026

Upper air analysis early this morning shows strong high pressure achored over the southwest US with troughing over the eastern US. Northwest flow between these two features will keep seasonal and mostly dry weather in place through the start of the new week.

By midweek, a compact upper shortwave will track through the northern Great Lakes Region, sending a cold front through a good portion of the Midwest states. This will bring our next chance for showers and storms. Out ahead of the front, temperatures will climb well into the 80s with steady moisture return sending dewpoints into the upper 60s to low 70s. Forecast guidance is showing moderately strong instability developing by Wednesday afternoon with seasonally strong shear. Forecast soundings depict inverted-V T/Td profiles with a large area of CAPE atop of that. A capping inversion will be in place most of the day, but will erode from west to east by late afternoon/early evening as the front approaches. Although the better upper forcing will be displaced to our north, a few strong to marginally severe storms could develop Wednesday afternoon and evening, posing a threat for damaging wind gusts.

Later this week, northwest flow aloft will become more zonal by the weekend. A few weak shortwaves traversing through the upper flow may spark occasional spotty showers, though most will stay dry. Longer range guidance shows a more defined wave/front moving through sometime later Saturday or Sunday, which would bring another chance for precipitation. Temperatures will remain seasonable through the end of the month with highs in the low to middle 80s.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 537 AM CDT Sun Aug 23 2026

VFR conditions are expected through today. Northwest winds will become light and variable overnight as surface high pressure settles in from the west. Recent guidance shows fog developing early Monday morning across much of central IL. Added TEMPO groups for MVFR visby reductions from 09-12Z at all airfields. Future adjustments will be needed to further refine things.

ILX WATCHES/WARNINGS/ADVISORIES

None.