textproduct: Central Illinois

KEY MESSAGES

- Today, there is a Marginal Risk (level 1 of 5) for east of I-55 (timing: daytime today), east of I-55, and a marginal risk that encompasses Knox County off to the west (timing: overnight into tomorrow morning).

- Wednesday, there is an Moderate Risk (level 4 of 5) along and near I-72/Danville and an Enhanced Risk (level 3 of 5) over the rest of the forecast area. Review your severe weather safety plan, and stay weather aware over the coming days.

- Breezy wind gusts are likely on Wednesday, with southwesterly gusts of 30-45 mph.

UPDATE

Issued at 914 AM CDT Tue Jun 16 2026

A cold front was analyzed just east of the Mississippi River in far NW IL at 14z. A small cluster of storms ahead of the front near I-55 has been producing pea sized hail, frequent cloud to ground lighting, and heavy downpours over the past 1-2 hours. Instability and shear are both meager this morning, so the severe risk is very low. However, this afternoon as the front pushes east of I-57, MLCAPEs rise to 500-1000 J/kg. Additionally, a 500 mb speed max moves overhead, increasing deep layer shear to around 50 kt. This should be sufficient to support isolated low-topped supercells north of I-70 and east of I-57. Forecast soundings indicate steep lapse rates below 6km, supporting short/fat cap profiles capable of producing severe hail. Also, dry sub- cloud layer below 1.5km supports accelerating downdrafts and isolated damaging wind gusts. CAMS show the primary timing for severe storms from 1-6 pm.

DISCUSSION

Issued at 216 AM CDT Tue Jun 16 2026

We are re-entering a busy, active pattern. Showers and thunderstorms have returned for today and tomorrow and some will pack a decent punch within them. Before we unpack the details of the next two days, let's talk general weather forecast. Temperatures this week will be pleasant, with highs in the upper 70s to low 80s and lows in the mid 50s to mid 60s. Wednesday will be the warmest, with areas south of I-70 having highs nearing 90. Southerly winds on Wednesday are going to be quite breezy, gusts up to 30-45 mph, ahead of the system, and will pull up very moist dewpoints northward.

Today a weak cold front will lob south through the forecast area, before lifting back north overnight as a warm front. SPC has a marginal risk for severe weather for eastern IL (risk: daytime today), east of I-55, and a marginal risk that encompasses Knox County off to the west (risk: overnight into tomorrow morning). The hazards of concern are gusty (up to 60 mph) winds and near severe/severe hail. The storms are expected to have the potential to be strong to marginally severe today. Current timing has the front entering west-central IL by 12z this morning and exiting the southeast by 22z-00z this evening. Uncertainty exists on how widespread of coverage there will be today. There is a chance that most people will likely see nothing from today's frontal passage. The RRFS indicates a fairly dry passage with some scattered convection along the front. The HRRR and NAMNest show a more solid line of showers and storms along the front, but different degrees of coverage.

Wednesday, an outbreak of severe weather is being forecast. SPC has increased areas along and near I-72/Danville to a moderate risk (level 4 of 5) with an enhanced risk (level 3 of 5) over (basically) the rest of the forecast area. The cold front from today will lift back up north as a warm front, lifting better moisture (dewpoints in the 70s and PWATS ~2 inches) into central and southeastern IL. There is a morning round (timing: ~12z-19z) of convection to the north of the warm front, that if a supercell can latch onto the warm front, tornadoes are possible. Otherwise, large hail and damaging winds are the concern for the morning round. There is some uncertainty on how far north the warm front will get. As of now, guidance shows it lifting somewhere between I-74 and I-80. If the warm front doesn't get as far north as I-80, then the threat (moderate risk) could be pushed further south for the cold frontal passage in the afternoon (timing: ~20z-06z). The environment will be very volatile. CAPE values 3000 J/kg or greater, effective bulk shear of 55-65 knots, and SRH 0-1 km ~200-300 m2/s2. Supercells are expected at the start of the afternoon round, but quickly evolving into a fast moving QLCS wind event with embedded tornadoes. All hazards are in play here, with some potentially being significant (EF2+ intensity, 75+ mph wind gusts, 2+ inch hail). These storms are going to be booking it, with storm motions nearly due east at 50-60 knots.

WPC has maintained an excessive rainfall high-end slight risk for Wednesday. PWATs look to be around 1.8-2.1 inches. The storms would likely have torrential rain within them, but will be moving fairly fast, which would hopefully help curb the flooding threat. With many rivers/streams already at or near flood and saturated soils, flooding could become a concern through Wednesday.

Beyond Wednesday, the next best chance of rain and storms comes Sunday but we need to survive through Wednesday before details can be clarified.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 555 AM CDT Tue Jun 16 2026

VFR conditions are expected through the 12z TAF period. A cold front will push through with some shower and thunderstorms (some strong) this morning into early afternoon. Confidence in coverage of storms isn't great, so expressed that with a PROB30 at SPI/DEC/BMI. Confidence is a bit higher for PIA and CMI. Winds will be out of the south to start, then will shift west mid morning, gusting to 20-25 knots today. Overnight winds will shift southerly again, although becoming light before the shift.

ILX WATCHES/WARNINGS/ADVISORIES

None.