textproduct: Central Illinois

KEY MESSAGES

- Mostly dry conditions are expected through Wednesday night, along with near normal temperatures, although isolated showers and thunderstorms are possible this afternoon to early evening (20 to 30 percent chance).

- Heavy rain and localized flooding risk Thursday and Friday: A stalling weather front could bring widespread storms late this week (60% chance). While widespread severe weather is unlikely, heavy downpours will introduce a localized risk of flash flooding and isolated damaging wind gusts.

- Potential for intense heat by mid-July: A powerful high- pressure system building over the central United States may bring a prolonged period of dangerous, excessive heat to the region next week, though exact timing remains uncertain.

DISCUSSION

Issued at 149 PM CDT Mon Jul 6 2026

Today through Wednesday: mostly dry but isolated thunderstorms...

Weak lift associated with a trough extending from the eastern Great Lakes Region to the Ozarks will allow for isolated to scattered showers and thunderstorms this afternoon into early evening. Meanwhile, an upper level high pressure ridge continues to build from the central Plains to the upper Midwest, and could tend to suppress shower activity to the northwest. Around 1000-1500 J/kg MLCAPE is expected this afternoon per SPC Mesoanalysis, although with weak deep layer shear under 20 kts. High- resolution models depict isolated shower and storm activity continuing until around 8 pm, especially east of the Illinois River, and this appears consistent with the synoptic pattern. Slow storm motions are expected, so precipitation amounts could be over an inch for localized spots as indicated by ensemble precipitation maxima, although in general little precipitation is expected.

For Tuesday, the pattern shifts slowly eastward, which should result in any shower and thunderstorm activity taking place farther southeast. For Wednesday, the base of the trough looks to shift into the lower Ohio Valley, which could bring another afternoon of isolated showers and thunderstorms to areas south of I-70.

Thursday through Saturday: wet pattern returning...

An increasingly zonal flow pattern will take place across the northern U.S. as a strong upper low suppresses the amplified ridge across the central U.S. This will allow a cold front to settle southward into the central IL vicinity, driven by shortwave activity through the zonal flow pattern, potentially stalling out nearby for a few days. As a result, an active weather pattern is anticipated as a couple of shortwave disturbances traverse the area along the frontal boundary, with a moisture-rich environment characterized by precipitable water values around 2 inches. This could yield a few thousand J/kg CAPE and deep layer shear around 40 kts and support severe thunderstorm potential, as well as heavy rainfall/flash flooding potential. Predictability of timing and location of these features remains low at this time, but will need to monitor in the upcoming days.

Sunday into next week: dry for a few days...

Late this weekend into next week, the pattern looks to amplify again, driving the cold front southward and drying out conditions again for central IL.

Temperatures near normal for most of the next week...

Temperatures look to run close to normal over the next week, with the exception of Thursday when highs look to approach 90 as the front approaches the area. In the long term, the building western Conus to central U.S. ridge could result in temperatures increasing for another heat wave, although the exact position of the ridge remains uncertain with some models continuing cooler conditions and periodic rain chances over the Midwest with more pronounced troughing farther west.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 545 PM CDT Mon Jul 6 2026

Isolated -SHRA will dissipate over the next 1-2 hours. Mainly clear skies expected tonight. Low dew point depressions and light winds will lead to some patchy fog with MVFR visibilities late tonight, most likely at KBMI-KDEC-KCMI. Scattered diurnal cu again on Tue, may go BKN at times. NE winds continue through the forecast at 5-10 kt.

ILX WATCHES/WARNINGS/ADVISORIES

None.