textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Mild to start the workweek, with the warmth peaking on Tuesday (highs in the mid 40s).

- The next low pressure system brings 20-45% light rain chances on Tuesday, followed by 35-75% light snow chances Wednesday.

- Turning colder for the second half of the week into next weekend.

SHORT TERM

Issued 310 PM CST Sun Jan 11 2026

Tonight through Monday night:

There remains some slight potential (~30% chance) that some snow flurries could develop over portions of southern WI this evening (especially east-central WI) between 8 PM and 11 PM CST this evening, driven by some weak 500mb PVA and 800-700mb WAA interacting with the shallow moist layer (containing the currently observed stratocumulus clouds across the region). That being said, with the cloud bases generally 2,000 ft above ground or higher, and plenty of dry air both above and beneath this layer, the odds of this happening have decreased since the prior forecast iteration. Either way, no measurable accumulation will come of it.

A southwest breeze develops tonight, working with the lingering cloud cover to hold overnight low temperatures to the mid 20s tonight (despite our thin snow pack). Continued dry and quiet weather on tap for Monday and Monday night, with highs around 40 degrees and lows around freezing.

Sheppard

LONG TERM

Issued 310 PM CST Sun Jan 11 2026

Tuesday through Sunday:

The unseasonably warm temperatures peak on Tuesday, with highs in the mid 40s expected. A low pressure system tracks east across Lake Superior Tuesday afternoon, with 20-45% rain chances across the region Tuesday morning and afternoon (highest in east-central WI), with a lull in the rain chances possible Tuesday evening (due to a dry slot resolved on most model guidance). Late Tuesday night, precipitation chances begin to increase again as a potent cold front and the 500mb trough swing through, with a rain/snow transition expected to complete at some point Wednesday morning. The daytime hours of Wednesday feature a 35-75% chance for light snowfall (highest further east in Wisconsin). ECMWF-ENS and GEFS total snow plumes describe the synoptic snowfall with this system as relatively light (with the plumes centered around a half inch to 1 inch snowfall, and some of the members making up the higher percentiles leaning towards 2-3 inches). Precip chances taper Wednesday night, but with 1 caveat, the due north winds on the back side of the low coupled with lake surface to 850mb delta T would suggest the formation of a lake effect snow band (oriented North-South somewhere towards the southern end of the lake). Exactly where this band sets up is uncertain, but we will have to monitor the exact wind directions to ensure that it doesn't meander west and clip far southeastern Wisconsin. Most ensembles take the lake effect band and it's heavier accumulations well clear of our CWA.

Cooler temperatures are expected for the late half of the work week, with daytime highs in the 20s to around 30. Another low pressure system with additional snow chances (possibly a clipper system) is possible later this week, followed by colder temperatures into the upcoming weekend.

Sheppard

AVIATION

Issued 310 PM CST Sun Jan 11 2026

1,700 to 3,000 ft AGL clouds between SCT and BKN coverage are present at the moment (as of 230 PM CST), this will continue to lead to periods of MVFR cloud ceilings through the remainder of the afternoon. Additional BKN high altitude clouds will be moving through at times today through tonight.

Intermittent MVFR ceilings persist into this evening, though the general model consensus (for now) is a gradual lifting and scattering, leading to predominantly VFR later tonight. Some scattered snow flurries may develop over east-central WI between 8 and 11 PM CST this evening (this is included as a PROB30 in the KSBM TAF at the moment, dry weather for the other TAF sites).

40 to 45 KT southwesterly winds at 2,000 ft AGL this evening and tonight will lead to some LLWS, which has been added to TAFs. For the surface wind field, light westerlies expected this afternoon, southwest around 10 KT tonight with a few ~20-25 KT gusts managing to mix down from the shear layer at times.

Sheppard

MARINE

Issued 310 PM CST Sun Jan 11 2026

Broad high pressure around 30.5 inches over the lower Mississippi River Valley will work with low pressure around 29.5 inches over Hudson Bay to drive southwest to west winds over Lake Michigan tonight. From late this evening through late tonight, a surface pressure trough extending south of the low will accelerate these winds (to around 30 kt at times). Winds gradually decelerate through the daytime hours of Monday.

Breezy south to southwest winds are expected Tuesday ahead of another low pressure system around 29.3 inches. This low pressure system will track east across Lake Superior Tuesday afternoon, shifting winds to northwesterly Tuesday night. There is potential for north to northwesterly gales behind the associated cold front Wednesday through Wednesday night. Moderate freezing spray may occur with these gales.

Sheppard

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...9 PM Sunday to 6 AM Monday.