textproduct: Central Illinois

KEY MESSAGES

- Areas of heavy rain are expected through tonight, with pockets of 2 to 3 inches not out of the question south of I-72.

- Locally strong to severe thunderstorms will be a threat this evening, and again Saturday from midday through the afternoon.

- Temperatures will warm back close to 90 degrees again next week, though oppressive humidity is not expected at this time.

DISCUSSION

Issued at 230 PM CDT Fri Jul 10 2026

Latest surface map shows a stationary front draped roughly along a Galesburg to Watseka line. Convection developed just north of this boundary beginning around midday, and has produced a few funnel clouds mainly north of our forecast area. Non-supercell tornado parameters through the afternoon suggest additional funnels may develop near/north of I-74 as storms develop, but will likely fade away once the rain begins. Much of the forecast area has reached the mid 80s as of 1 pm, though some lower temperatures were noted south of I-70 where clouds have been more extensive so far today.

Short Term (Through Sunday):

Main forecast concern remains with the period through Saturday, involving timing of rain chances and any potential severe weather or flooding.

Regional radar mosaics early this afternoon show an MCS developing over northwest Missouri. While the core of this should track to our southwest, residual boundaries and/or MCV's will help trigger additional storms further northeast, which are most favored to cross central Illinois during the evening. HREF precipitable water values increase to near 2 inches near/south of I-72 by this evening, supporting areas of heavy rain and potential for flooding. Localized probability-matched means (LPMM) suggest potential for over 2 inches of rain with the heavier storms, and a level 2 risk of excessive rainfall covers the entire forecast area. While some areas of southeast Illinois did receive 2-3 inches of rain last evening, coverage of that intensity was not really widespread, with antecedent conditions being rather dry before that. Will hold off issuing a Flood Watch at this time, but will need to watch this closely.

The boundary is expected to settle near I-72 by early Saturday morning. Several of the CAM's suggest redevelopment just south of this area by midday, though the NAM-Nest looks more like a prominent MCV or small-scale low pressure area. Recent SPC Day2 outlook brought the level 1 risk up to about I-70, for locally damaging winds during the afternoon.

As an upper trough settles into the Ohio Valley, several models are suggesting it will pinch off an upper low. This would keep a threat of rain continuing into Sunday over portions of the forecast area, primarily near and south of I-70.

Long Term (Monday through Friday):

Expansive upper ridge is still progged to cover a large portion of the CONUS early in the work week, centered over the northern Plains. A bit of a rex block pattern sets up, with the upper low lingering over the lower Mississippi Valley. With time, the center of the high finally slides off to the southeast, though ridging redevelops over the Rockies and western Plains by late week. The overall pattern much of the week is not favorable for any precipitation in our area, though some of the guidance suggests the lower Mississippi Valley low may be close enough for some showers in southeast Illinois. Better rain chances return toward late week, as we start to get more into a northwest flow and convection slides along the periphery of the ridge.

Temperatures through the week remain quite warm, though the rex block pattern will cut off any meaningful moisture advection, keeping heat index readings in check.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1219 PM CDT Fri Jul 10 2026

While some brief MVFR ceilings have occurred late this morning from KGBG-KBMI, main aviation concern into the evening will be timing of convection. While a few showers/storms are possible during the afternoon, main period of concern appears to be 00-06z, especially from KSPI-KCMI. Heavy rain with the stronger storms will result in temporary visibility drops below 2SM in a few areas.

With a front settling over central Illinois overnight, concern shifts to lower ceilings. Morning HREF run shows about a 30-50% chance of ceilings below 3000 feet at the terminals beginning around 09-10z, with some potential for them to linger into late morning close to the boundary.

ILX WATCHES/WARNINGS/ADVISORIES

None.