textproduct: Chicago

KEY MESSAGES

- A relatively quiet pattern will continue through the weekend with a few snow showers today near the Wisconsin state line, and near the Lake Michigan shoreline tonight into Sunday.

- A period of warmer, and wetter, conditions is expected next week into the second full week of March.

DISCUSSION

Issued at 129 PM CST Sat Feb 28 2026

Through Sunday Night:

It's a rather banal day across the region with broken upper- level cloud cover and northeasterly winds. A band of snow continues to meander across southeastern Minnesota and southern Wisconsin, with dry air largely limiting any meaningful southward penetration into northern Illinois. Temperatures across the area vary from north to south, ranging from near freezing along the Wisconsin state line to around 50 near US-24.

Tonight, a 1035mb surface high will build into the Upper Great Lakes and support an increase in northeasterly flow and cold air advection down Lake Michigan. In spite of marginal inversion heights (a consequence of the cyclonic shear axis of the upper- level flow remaining well northeast of our area), increasing shoreline convergence should support a gradual increase in lake- induced stratus, flurries, and a few show showers. In all, this set-up looks pretty darn marginal, so will only advertise a dusting to perhaps a few tenths of an inch of snow accumulations should bonafide snow showers actually develop. Elsewhere, tonight will be relatively chilly with overnight lows in the upper teens (northwest) to mid 20s (southeast).

Lake effect flurries and snow showers may continue near the Lake Michgian shore through Sunday morning before tapering in coverage during the afternoon as the surface high meanders through the central Great Lakes. Partly cloudy skies and continued northeasterly winds will otherwise define an unremarkable day with highs generally in the 30s.

Tomorrow night looks similarly quiet with light easterly flow, broken cloud cover, and overnight lows generally in the upper teens to lower 20s. With the baroclinic zone expected to stall across southern Missouri, Illinois, and Indiana, any precipitation with the next wave propagating into the Mississippi River Valley should miss our area.

Borchardt

Monday Onward:

A broader zonal flow regime with an embedded slow-moving trough over the central Rockies early in the week will transition to a much more meridional pattern highlighted by deep western troughing for the second half of the week. Meanwhile, an expansive Bermuda High will foster a persistent feed of Gulf and Caribbean moisture toward the central CONUS through the period. This will ultimately result in a seasonably mild to unseasonably warm period with several rounds of rain and localized convection over the area. While axes of heavy rain appear likely over the mid-Mississippi and Ohio River valleys, it remains to be seen where those axes set-up and whether those axes align over the same location and result in flooding concerns.

Initially, broad low-level isentropic ascent combined with modest moisture transport will bring the first area of precip over the area late Monday night into Tuesday. While rain is favored, low-level wet-bulb temps near freezing could result in minor impacts from light freezing rain close to the Wisconsin state line through mid-morning.

Beyond Tuesday, the spread in the ensemble suite, owing to the differences in the evolution of the western trough, offers less confidence on exactly when and where heavy rain axes develop. However, with PWATs around 1.5" (300% of normal), any pronounced wave emanating from the western trough will induce sufficient forcing to realize focused axes of heavy rain. As a whole, the best focus mid to late week remains just south of the forecast area Tuesday night.

Will also need to keep an eye on the potential for more organized convection in or around the area late Thursday and especially Friday as a large portion of the western trough ejects toward the mid to upper-Mississippi River Valley.

Kluber

AVIATION /18Z TAFS THROUGH 00Z MONDAY/

Issued at 1200 PM CST Sat Feb 28 2026

Forecast concerns for the terminals...

- Period of snow showers/flurries this afternoon, mainly near the IL-WI line.

- MVFR ceilings to develop this evening and persist through Sunday morning.

- Non-zero chance (10-15%) for lake effect flurries late tonight into Sunday morning.

A band of snow has developed across southern MN and WI this morning and will continue to organize as it pivots eastward through the afternoon. The band is expected to remain north of our area in WI, but a few snow showers and/or flurries have been seen across portions of far northern IL and that should continue through the afternoon. Beneath any snow showers/flurries this afternoon visibilities will briefly dip into the 3-4 mile range with some MVFR clouds expected as well. The greatest confidence for these snow showers/flurries remains near RFD but a there remains a 20-30% chance for a couple of flurries as far south as ORD and MDW. Regardless, little to no accumulation is expected due to marginal surface temperatures (33-36F) and poor quality snow.

Heading into this evening, ceilings will begin to lower into the 1500-2500 ft range over Lake Michigan and spread inland on the northeast winds. Therefore, a period of MVFR ceilings is expected tonight and through the morning on Sunday before skies begin to scatter back to VFR Sunday afternoon. Additionally, a band of lake effect snow is expected to develop tonight and mainly impact areas near the IL-WI line, but there is non-zero chance (10-15%) that the band could drift into the Chicago area terminals after 09z tonight and linger through Sunday morning. Given the low confidence on lake effect snow coverage have opted to forego a formal mention in the TAFs but will keep a close eye on trends.

Otherwise, expect northeast winds to prevail through the period with speeds around 8-12 kts. Though, a few gusts around 20 kts may be seen this evening and overnight as a surface low drifts across the Ohio River Valley.

Yack

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 3 PM CST Sunday for Winthrop Harbor IL to Burns Harbor IN.

Small Craft Advisory until 3 PM CST Sunday for Burns Harbor to Michigan City IN.