textproduct: Central Illinois

KEY MESSAGES

- There is a marginal risk (5-15% chance) for severe weather along and south of I-70 from 2pm to 8pm today. The primary hazards will be strong wind gusts and large hail...although an isolated tornado cannot be ruled out.

- After a windy and very warm day with highs soaring into the middle to upper 70s, there is a Slight Risk (15-30% chance) for severe weather west of the I-57 corridor Friday night as a cold front approaches from the west.

..Severe Weather Risk Friday Night

After a few lingering showers mainly Thursday morning, a period of mostly dry weather is expected Thursday afternoon and evening before another prominent short-wave trough currently off the coast of the Pacific Northwest approaches. As the deep-layer flow pattern becomes more southwesterly ahead of the wave, the persistent frontal boundary draped along the I-70 corridor will surge northward late Thursday night into Friday morning, triggering a few showers and thunderstorms. While widespread severe weather is not anticipated with FROPA, will need to monitor the potential for some hail with the stronger cells. Any morning convection will quickly lift into Wisconsin/Michigan by midday...followed by a windy and very warm afternoon with highs soaring into the middle to upper 70s. Despite the warmer/more humid airmass flowing into the region, a lack of forcing and the presence of mid-level capping will prevent any storm development during the day. Meanwhile further upstream, low pressure associated with the short-wave trough will track from western Kansas Friday morning to Lake Superior by Saturday morning. Given the very unstable/sheared environment ahead of the low and its associated cold front, a broken line of strong to severe convection is expected to develop from Iowa to central Texas by late afternoon. These cells will track northeastward and will eventually spill into the Illinois River Valley late Friday evening. Despite daytime instability waning after dark, a powerful 55-65kt 850mb jet streak will develop ahead of the front from Texas to the Great Lakes. This will add plenty of wind energy to the atmospheric profile and will substantially increase the chance of damaging wind gusts being mixed to the surface once the convection arrives. As a result, SPC is highlighting all locations west of the I-57 corridor with a Slight Risk (15-30% chance) for severe weather. Current projections suggest this will be a nocturnal wind event from late evening into the overnight hours. The exact eastward extent of the risk area remains in question and will be fine-tuned over the next few forecast cycles as details become clearer.

Barnes

AVIATION

(For the 12z TAFs through 12z Thursday Morning) Issued at 542 AM CST Wed Mar 4 2026

IFR ceilings/visbys are present at all central Illinois terminals except KPIA early this morning. A NE wind of around 10kt has helped drier air from northern Illinois cause a higher ceiling at KPIA:however, NAM/HRRR guidance suggests cloud bases will gradually lower to IFR at KPIA by around 18z. A few showers will skirt along/south of I-72 through 14z/8pm...followed by a period of mostly dry weather before a wave of showers/storms approaches from the southwest this afternoon. This convection will largely remain further south along the I-70 corridor: however, it may track far enough north to warrant thunder mention at KSPI/KDEC/KCMI between 19z and 23z. After that, another lull in precip will be observed before a renewed round of showers/thunder arrives overnight. Confidence remains low concerning the timing and track of the overnight storms, so have carried a PROB30 group for thunder at the I-72 terminals and just mentioned showers at KPIA/KBMI. Another aviation forecast challenge will be visibilities. With central Illinois remaining north of a stationary frontal boundary today/tonight, fog will be persistent. CAMs suggest visby reductions throughout the day...with fog potentially becoming dense by tonight. At this point, have lowered visbys to around 1/2 mile at all sites after the 03z-05z time frame.

Barnes

ILX WATCHES/WARNINGS/ADVISORIES

None.