textproduct: Central Illinois

KEY MESSAGES

- Dry conditions and low humidity continue through tomorrow, with high temperatures reaching the 80s.

- A pattern change brings increased humidity and frequent thunderstorm chances starting Friday and continuing into next week. Afternoon heat indices will likely peak in the upper 80s to mid 90s for Saturday and beyond.

DISCUSSION

Issued at 136 PM CDT Wed Jun 3 2026

High pressure is set up over the Great Lakes region again today, which is dominating the weather pattern for much of this week. Dry conditions, light winds, and limited cloud cover are supporting large diurnal swings with highs today in the mid 80s and lows tonight in the upper 50s.

Starting tomorrow, the high pressure center will drift off to the mid-east coast, shifting the flow to a more south-southeasterly direction. This will support increasing moisture as we go into the weekend. Highs will increase to the upper 80s, potentially 90 in some spots, with dewpoints in the mid 60s to low 70s for Friday into Monday. Heat indices could bump north of 90 degrees by Saturday and looks to potentially continue into the new week. In conclusion... summer has arrived.

The ridging pattern starts to break up Friday as a shortwave pulses through the region, bringing rain chances into the forecast. The showers and thunderstorms on Friday into Saturday appear to have the ability to be efficient rain producers with PWATs around 1.6-1.9 inches. However, the forcing will be pretty weak, making coverage of the showers and thunderstorms not as widespread as we would like, with the recent dryness we have experienced. The higher rainfall amounts will be localized where multiple showers or thunderstorms pass over the same area during this time. The shear is weak during this wave, so a severe weather risk should stay minimal.

The long range forecast remains uncertain at this time, starting early next week. By midweek (next week), the upper level flow is questionable on how it will be set up. There does appear to be the possibility of a few more weak rounds of convection into net Wednesday. The extended forecast relies heavily on the NBM due to that uncertainty. Looking beyond the seven-day window, the CPC 6-10 day outlook highlights a strong signal for a persistence of above- normal temperatures across the central U.S.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1220 PM CDT Wed Jun 3 2026

Some high cirrus clouds are floating overhead this afternoon, but VFR conditions are in place through the entire 18z TAF period. Southerly winds will be 6-10 knots through tomorrow.

ILX WATCHES/WARNINGS/ADVISORIES

None.