textproduct: Central Illinois

KEY MESSAGES

- Rain chances will be highest late this afternoon into early evening, then again Friday night. A few of the storms will be on the strong side, but the main threat of that will be south of I-72.

- Locally heavy rain will result in the potential for areas of flooding, with the focus shifting more into areas south of I-72 by Friday night.

- Temperatures remain typical for July. While a warming trend takes place next week, humidity levels will make it feel less oppressive than last week's heat wave.

DISCUSSION

Issued at 116 PM CDT Thu Jul 9 2026

Short Term (through Saturday):

Prominent MCV from the decaying convection across Missouri is about to cross the Mississippi River south of Pittsfield. Despite a fair amount of cirrus blowoff, MLCAPE's of 1000-1500 J/kg have allowed scattered storms to develop over the last hour across eastern Illinois. Recent Day1 convective outlook shifted the risk areas a little further south and are mainly concentrated south of I-72. Greatest downdraft CAPE is expected preceding the anticipated convection across central Illinois, though there remains some uncertainty with the extent of strong/severe storms. In general, much of the shower/storm activity is expected through sunset. While development of another MCS across Missouri is expected this evening, most of the high-res guidance keeps this to our southwest.

A front across Iowa and southern Wisconsin is expected to only slowly drift southward the next couple days. Additional convective complexes are expected to ride along the boundary Friday night, and highest rain chances remain over the south half of the forecast area during this time. East-west upper troughing will set up during the weekend, keeping the frontal movement on the slow side. However, by late Saturday night, it should finally be near the Ohio River, ending the rain threat.

Long Term (Sunday through Thursday):

Little change in the forecast for next week. A sprawling upper high will dominate a large portion of the CONUS to start the week, before the ridging amplifies near the Plains by midweek. This pattern will result in seasonably warm temperatures near 90 degrees in our area, though with the Gulf cut off, humidity levels should not get as rough as last week's heat wave. Still, heat index levels of 95-100 degrees are likely Tuesday-Thursday.

As the upper ridge establishes itself, we'll be on the periphery of a northwest flow, which can be favorable for MCS activity. Right now, that activity looks to be more across the Great Lakes region, so a dry forecast will be maintained in the extended period.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1225 PM CDT Thu Jul 9 2026

Thunderstorms are expected to develop early this afternoon, as a small scale disturbance moves out of Missouri. Main focus for convection will be in the KSPI-KCMI corridor, closest to the track of this feature. Will include a 3-4 hour TEMPO period in this area for the highest potential, but maintain PROB30 groups at KPIA/KBMI where development is less certain.

Going later into the night, focus shifts toward MVFR or potential IFR conditions, as a front settles into the area and winds become nearly calm. HREF probabilities of ceilings below 1000 feet peak around 11-13z at 40-60%. Will need to watch for this potential with upcoming TAF issuances, but for now, will go with MVFR ceilings mainly on the lower end.

ILX WATCHES/WARNINGS/ADVISORIES

None.