textproduct: Chicago

KEY MESSAGES

- Periods of showers and thunderstorms through Saturday morning. Some thunderstorms may be strong to severe, especially this afternoon and early Saturday morning.

- Areas of dense fog improving from south to north today, ending last along the IL Lake Michigan shore.

- Chance for thunderstorms next Tuesday night.

DISCUSSION

Issued at 206 AM CST Fri Mar 6 2026

Dense fog continues across much of the area south of I-80 and then over Lake Michigan and the lakeshore areas. Expecting gradual improvement from south to north this morning as the warm from lifts north but this may also allow dense fog to develop across areas north of I-80 for a few hours before precipitation arrives later this morning. Overall confidence is low and trends will need to be monitored. Dense fog will likely persist along the IL lakeshore for much of the day, finally dissipating later this afternoon or early this evening near the IL/WI state line.

A large area of thunderstorms extending from southern MN into far northern MO is expected to continue lifting northeast, reaching the western cwa around daybreak and then continuing across the northern two thirds of the area through the morning hours. Most recent guidance suggests there may be a sharp cutoff on the southern edge of this precipitation with the southern third or so of the area possibly remaining mainly dry for today and if that trend were to pan out, pops would need to be lowered for this area with later forecasts. As this precipitation spreads across the area, any remaining dense fog would begin to lift/dissipate, at least slowly.

The severe threat with this morning's activity looks to be fairly low with possibly some isolated large hail being the main threat during this time period. Locally heavy rain would also be possible.

There remains quite a bit of uncertainty for additional thunderstorms as well as coverage this afternoon into early this evening. The warm front will be lifting north across the area with favorable conditions for at least isolated severe storms. It appears the best chances for additional thunderstorms would be along and north of I-80 but given the uncertainty for how much will develop have maintained only chance pops during this time. If thunderstorms do develop, all modes would be possible, large hail, damaging winds and possibly a tornado. But at this time, low coverage is expected. This activity would end during the early evening as the warm front is expected to be north of the area with a lull in the precipitation expected during the mid evening.

Additional thunderstorms are expected late this evening into early Saturday morning ahead of a strong cold that will be moving across the region and passing across the local area mid/ late Saturday morning. Coverage during this time looks to be a bit better, perhaps precipitation across most of the area, but this activity would likely be in the form of a line and moving fairly quickly. Strong to isolated severe thunderstorms would also be possible during this time. This activity would be exiting the local area by mid morning Saturday.

Temps are currently holding steady in the mid 40s for much of the area, 50 south and then upper 30s near the lake. Temps will be steadily rising this morning with highs well into the 70s south of I-80 later today. Temps will likely slow their rise across northern IL with the expected precipitation through midday. High temps could be in the late afternoon or even the early evening in these areas. Temps by Saturday morning may still be in the upper 50s/lower 60s for most areas and then as the cold front moves east across the area Saturday, temps will begin to fall and its possible that temps will be in the lower/mid 40s by early Saturday evening.

West/northwest winds may gust into the 35-40 mph range with and just behind the cold front Saturday and the pattern looks to remain breezy/windy Sunday into Monday with above normal temps in the 60s Sunday and lower 70s Monday.

Models show another potential storm system for the Tuesday/ Wednesday time period next week with a frontal boundary possibly across the local area with a large temperature gradient. Showers along with thunderstorms for at least part of the area would be possible during this time period. cms

AVIATION /12Z TAFS THROUGH 18Z SATURDAY/

Issued at 552 AM CST Fri Mar 6 2026

- LIFR/VLIFR conditions this morning in fog and low stratus. Improvement expected from south-to-north after about 15-16z. - Winds turning S and SSW this afternoon. Strengthening gusts this afternoon, particularly INVOF GYY and MDW where gusts could eclipse 30 knots.

- Prolonged period of VCTS and/or TSRA at RFD today.

- Scattered showers and storms expected later this morning into the afternoon in the vicinity of the c90 tracon.

- Period of LLWS this evening and overnight.

- Additional waves of showers and embedded thunderstorms tonight into Saturday morning.

Widespread LIFR/VLIFR conditions are ongoing across the region. At RFD, vsbys and cigs should begin to lift as showers and thunderstorms arrive through about 13z, but VCTS and periodic on-station thunderstorms will likely continue through the balance of the day. At the Chicago-area terminals: improvement from south-to-north is anticipated after about 15-16z as winds increase. This should help to lift and erode the lowest cigs and vsbys, although AMDs will likely be needed to refine this timing a bit. Waves of showers and thunderstorms will spread east through the morning. At this time, the greatest chances for VCTS and brief TEMPO TSRA exists at ORD and DPA, with relatively lower chances near GYY. Additional rounds of thunderstorms are possible this afternoon and evening, although confidence in storm development during this timeframe remains somewhat low. For the time being, have continued with PROB30 mentions for TSRA.

As a warm front works its way northward this afternoon, winds will turn S and then SSW. It's unclear how far north the front will make it, with indications pointing to the strongest winds materializing at MDW and GYY this afternoon. It's possible that a brief period of gusts over 30 kts materializes during the afternoon as the front lifts northward.

Another round of showers and embedded thunderstorms will develop late tonight into Saturday morning. The potential for TS remains a bit too nebulous at the Chicago-area terminals to justify TEMPO groups or VCTS at this time, but have introduced a mention at RFD. Eventually, winds will become westerly and gusty into Saturday morning with low MVFR conditions in the wake of a cold front.

Carlaw

LOT WATCHES/WARNINGS/ADVISORIES

IL...Dense Fog Advisory until 10 AM CST this morning for ILZ003- ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013- ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103- ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

IN...Dense Fog Advisory until 10 AM CST /11 AM EST/ this morning for INZ001-INZ002-INZ010-INZ011-INZ019.

LM...Dense Fog Advisory until 3 PM CST this afternoon for the IL nearshore waters.

Dense Fog Advisory until 10 AM CST this morning for the IN nearshore waters.