textproduct: Milwaukee/Sullivan

KEY MESSAGES

- A lake effect snow band is forecast come onshore early Sunday morning into Sunday afternoon. This band may only wobble onshore a few miles, with scattered snow showers inland. Still, expecting moderate to heavy rates within the band, leading to snowfall of 2 to 4 inches in eastern Racine and Kenosha Counties. A Winter Weather Advisory is in effect for these areas 6 AM CST to 3 PM CST Sunday.

- Wind chills between negative 15 and negative 20 degrees are expected tonight into early Sunday morning.

- A Cold Weather Advisory for wind chills of negative 20 to negative 25 degrees will likely be needed Sunday night into Monday morning.

- Wind chills in the negative teens are expected each night Monday through Wednesday.

SHORT TERM

Issued 324 PM CST Sat Jan 24 2026

Tonight through Sunday night:

Very light snow is possible along the Wisconsin and Illinois border this evening into tonight as low pressure develops in the Lower Mississippi Valley, with trace accumulations possible in some spots. Expecting lows in the single digits below zero, with wind chills in the negative teens to locally negative 20 degrees.

As low pressure begins to organize late tonight into Sunday morning and high pressure lingers over the western Great Lakes region, expecting convergence over Lake Michigan to strengthen, allowing for a lake effect band (already developed over the central portions of the lake) to become well organized. Water temperatures in Lake Michigan remain in the 1 to 2 degrees C range, with 850 mb temperatures in the -15 to -19 degree range. This leads to a temperature difference of 16 to 21 degrees, which is well within the preferred range for moderate to heavy rates. In addition, the saturated/unstable column is solidly within the dendritic growth zone, increasing potential for high ratio snowfall. With these ingredients in play, rates of 0.5 to 1"/hr are possible within the core of the band.

With all that said, the question becomes whether the core of this band can make its way onshore early Sunday morning. As low pressure ejects into the Southeast U.S. and turns winds over Lake Michigan to northeasterly, high pressure lingers over the western Great Lakes. This will have the dual purpose of keeping the band organized, but also potentially preventing the band from moving inland more than a few miles. 12Z mesoscale runs make a solid case for the convergence zone meandering westward into eastern Racine and Kenosha County, with a few models indicating areas as far north as Milwaukee and as far west as I-94 could see impacts from the band. For now, with confidence increasing, have issued a Winter Weather Advisory for Racine and Kenosha Counties for 2 to 4 inches of snow. Localized areas near Lake Michigan may see up to 6 inches where the band lingers longest.

Low pressure finally departs into the mid-Atlantic Sunday afternoon, and winds will shift back to northwesterly accordingly. This will allow the band to progress back eastward into open waters, with Arctic high pressure moving back in behind the band as it exits.

Outside of the lake effect banding, expect generally cloudy to partly cloudy skies and highs in the single digits above zero. Within the band, expect highs in the positive teens.

Sunday night, with northwesterly winds continuing and an Arctic airmass returning, expect temperatures to drop to around negative 10 degrees inland from Lake Michigan and into the negative single digits near Lake Michigan. Wind chills in the negative 20 to negative 25 range are expected, and a Cold Weather Advisory will likely be needed. Wind chills will gradually improve through Monday morning.

MH

LONG TERM

Issued 324 PM CST Sat Jan 24 2026

Monday through Saturday:

Winds will shift southwesterly ahead of a clipper system traversing northern Wisconsin Monday, bringing highs around positive ten degrees. A few snow showers are possible across central Wisconsin (15 to 20 percent chance). A cold front from this system will progress through southern Wisconsin Monday night, bringing gusty northwest winds and windchills in the negative teens (lows in the single digits). Northwesterly flow continues through at least midweek, with windchill values in the negative teens each night through Wednesday. Wednesday night into Thursday, the next clipper system approaches, with this one projected to impact central Illinois. A few snow showers are possible across southern Wisconsin (15 to 20 percent chances) Wednesday afternoon through Wednesday night. Arctic high pressure building in Thursday through Friday will bring light winds and therefore improving wind chills through the end of the week. High pressure slides eastward with a return to more seasonable highs in the teens to low 20s Friday and Saturday.

MH

AVIATION

Issued 324 PM CST Sat Jan 24 2026

VFR conditions and light and variable winds continue into this evening, with light north winds developing late tonight into Sunday morning and shifting northwest Sunday afternoon.

A band of lake effect snow is expected to wobble onshore between early Sunday morning and mid Sunday afternoon towards the shoreline of far southeastern WI (mainly affecting KRAC and KENW, with a glancing blow to KMKE possible). Exactly how long (within this time window) it remains onshore is uncertain, but while it is present, MVFR ceilings as low as 1000 ft, moderate to briefly heavy snowfall, and IFR/LIFR visibilities are possible. If central portions of the snow band make it to shore, 0.5 to 1 inch per hour snow rates should develop. By 4 PM CST Sunday afternoon, surface winds will shift far enough northwest to eject the lake effect snow band, leaving dry weather thru Sunday night and onwards.

Sheppard

MARINE

Issued 324 PM CST Sat Jan 24 2026

Open Waters / Synopsis:

High pressure of 30.7 inches will remain over the western Great Lakes through today, with a convergent zone bringing lake effect snow potential to the southern half of Lake Michigan from this afternoon into Sunday. High pressure slides eastward tonight as low pressure of 29.6 inches develops in the Lower Mississippi Valley. Expect the convergent zone to strengthen tonight, with lake effect snow continuing. Northeasterly winds are expected east of the band, with northerly winds west of the band. The band will transition westward toward Wisconsin Sunday morning, then back eastward Sunday afternoon and evening. All winds shift to northwesterly Sunday evening as low pressure moves into the mid- Atlantic. High pressure centered over the southern Plains then dominates the pattern through midweek, leading to generally westerly winds. A few clipper systems are possible early to midweek, bringing periods of 25 to 30 kt gusts. Gusty winds combined with frigid temperatures will lead to moderate / heavy freezing spray Sunday night through Tuesday. A Heavy Freezing Spray Warning is in effect.

Nearshore Zones:

As the aforementioned convergent zone over southern portions of the lake on Sunday brings breezy northwest / northeast winds to the western edge of Lake Michigan, waves build to Small Craft thresholds. As such, a Small Craft Advisory goes into effect for zones south of North Point Lighthouse 9 AM CST Sunday morning. Winds turn northwest later Sunday and allow waves to dissipate, but with gusts up to 25 knots, the Advisory will remain in effect through Noon CST Monday. These winds will remain near or just below thresholds further north.

After a brief lull in the winds Monday afternoon, gusty southwest to northwest winds are expected for all nearshore zones Monday evening through Tuesday afternoon. An additional Small Craft Advisory is looking likely.

Sheppard

MKX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory...WIZ071-WIZ072...6 AM Sunday to 3 PM Sunday.

LM...Heavy Freezing Spray Warning...LMZ080-LMZ261-LMZ362-LMZ364- LMZ366-LMZ563-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876- LMZ878...6 PM Sunday to 6 PM Tuesday.

Small Craft Advisory...LMZ645-LMZ646...9 AM Sunday to noon Monday.