textproduct: Chicago

KEY MESSAGES

- Temperatures drop into the teens tonight with a gradual warming trend expected through the weekend into next week.

- Chance (20-30%) for a wintry mix across far northern IL Sunday evening.

UPDATE

Issued at 829 PM CST Thu Jan 1 2026

Some minor updates made to the overnight forecast, primarily to slow clearing of clouds across much of the area and to raise overnight temps slightly with the more persistent stratus deck.

Extensive stratus deck lingers across the northeast half or so of the forecast area this evening, roughly north of a Savanna to Kankakee and Fowler IN line. Gradual lowering of the subsidence inversion in the wake of the mid-level disturbance which brought some light snow to far northeast IL earlier toady is expected eventually lower enough to break holes in the cloud deck. Satellite trends indicate that this is occurring more slowly than much of the earlier guidance had depicted. Latest hourly high-res guidance (RAP particularly) reflects this trend, and thus have adjusted forecast to maintain mostly cloudy skies with scattering predawn. Stratus layer does appear fairly thin per forecast soundings, so can't rule out a quick scattering at some earlier time, though at this time it looks like clouds will hang tough for a while tonight.

Beneath the cloud cover, temperatures have been holding fairly steady in the mid-upper teens, and have therefore also adjusted hourly temps up and increased our mins a bit as well.

Otherwise, forecast is in good shape on this quiet first night of 2026.

Ratzer

DISCUSSION

Issued at 142 PM CST Thu Jan 1 2026

Through Friday:

Low-level dry air has proven formidable this afternoon keeping the snow mainly north of I-90 as opposed to getting as far south as Chicago. Where the fluffy snow has managed to reach the surface, roadways readily became at least partially snow covered given the cold temperatures, especially across northeast Lake County, IL. Any lingering snow is expected to gradually taper off over the next few hours as the weak disturbance continues to track southeast of Lake Michigan, with dry conditions then forecast areawide for the remainder of the evening.

Another chilly night is in store with temperatures forecast to drop into the teens across the area. There is the potential that some high clouds sneak into the southwest CWA which could limit cooling to the lower 20s but confidence in that timing is on the lower side. Friday looks quiet locally with temperatures warming into the mid to upper 20s with increasing high cloud cover expected through the afternoon associated with a disturbance tracking toward central/southern Illinois, which is expected to remain south of the area.

Petr

Friday Night through Thursday:

There is another weak clipper system that will be moving across the midwest Saturday into Saturday night. Appears the best chance of any light snow will remain north of the local area but will need to monitor trends for any possible light snow into far northeast IL. Temps will remain near or just below normal into Sunday when warm air advection begins with above normal temps expected for much of next week. The local area will be on the far southern end of a band of precipitation that develops later Sunday afternoon into Sunday evening. If precipitation does occur, it will probably be short in duration and also a wintry mix. The blended guidance has low chance pops generally along and north of I-88 Sunday evening and this seems reasonable. Confidence for precip types remains low, but freezing rain/snow is plausible and made no changes.

With the expected warmer temps, precip types later next week look to remain all rain though there is uncertainty for precip timing. Decent ensemble support for a system in the Thursday/ Thursday night time period, though there is still timing differences. Blended guidance continues chance pops on Thursday and made no changes. cms

AVIATION /00Z TAFS THROUGH 06Z SATURDAY/

Issued at 1102 PM CST Thu Jan 1 2026

No significant aviation forecast concerns for this TAF cycle.

A mid-level disturbance continues to track away from the region across the northern/eastern Great Lakes late this evening. Other than a lingering VFR stratus layer and gradually veering light surface winds, no major impacts were occurring across the terminals. Subsidence in the wake of the departing disturbance is expected to continue to lower an inversion across the region tonight into early Friday, which should eventually lead to breaks developing in the stratus. Model guidance has been too bullish in scattering/clearing out the stratus (as expected), though do expect this will eventually occur early Friday morning though confidence is somewhat low with this. Also, can't rule out some patchy MVFR cloud bases developing Friday morning as the eastern periphery of lower level moisture over parts of IA/MN spreads east. Not expecting widespread MVFR CIGs at this time, but have indicated some FEW020-025 for this. Eventually increasing VFR high/mid clouds will spread across the area later Friday/Friday night in response to another disturbance dropping southeast across the Plains to our west.

Surface winds which are currently light/variable or light westerly across the area will become northwest 5-10 kts by morning, and eventually more north-northwest later Friday and Friday night.

Ratzer

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...None.