textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Light snow moving out over Lake Michigan late this evening

- Accumulating, light snow is likely Saturday night into early Sunday. - Below normal temperatures will persist into next week, with additional rounds of light snow possible at times.

UPDATE

Issued 922 PM CST Fri Dec 5 2025

The last of the light snow is moving through south eastern WI late this evening and will push out over Lake Michigan over the next hour or so. Environment saturated enough through the column where the freezing drizzle potential did not materialize. Otherwise looking as a few lingering flurries and cloud cover to persist overnight as a cold front works its way across the area, which will keep temps fairly steady in the 20s into daybreak. Then will see clouds break and a colder airmass arrive behind the passing cold front into Saturday morning. And still looking at another round of accumulating snow Saturday night into Sunday with widespread 1-3 inches. Initial look at 00z models trickling in, the better chances for higher snow totals 2-4 inches continue for area south of I-94 toward the WI/IL. Will also need to keep an eye along southeastern WI lakeshore as we continue to see hints of potential lake-effect band setup, which would boost totals a bit.

Wagner

SHORT TERM

Issued 310 PM CST Fri Dec 5 2025

Tonight:

Light snow spread into western WI and will continue to march eastward across the rest of WI this evening. This is tied to mid level vorticity advection and low-mid level warm air advection that are associated with a trough of low pressure. Mid levels are saturating first, and then it takes a little time for the snow to start reaching the ground. Tracking the steadier area of snow upstream, it should arrive in the Madison area around 5 pm and Waukesha around 730 pm. While the better forcing will pull toward northeast WI, the precip coverage will be rather broad and most of southern WI (including with WI/IL border) should see at least some flurries. Accumulations toward central WI will also be light, with up to a half inch.

Drier air will overspread the mid layers in southern WI late this evening behind the trough. This will dry out the snow growth layer and there continues to be a risk for some light freezing drizzle over southern WI between 8 pm and midnight. This is due to lingering low level moisture and very weak frontogenesis to produce a small amount of lift (about -2 mbar/sec omega) before all the moisture departs. If freezing drizzle occurs, then a light glaze is possible, mainly on elevated and untreated surfaces.

Saturday through Sunday:

The next system will arrive in southwest WI early Saturday evening as low pressure tracks into Nebraska. Light snow will overspread southern WI Saturday night as the low goes through Iowa and northern IL. This is a compact system tied to a weak shortwave trough, but the northern portion of that trough slows down a bit as it crosses WI, while the southern portion (main show) and the low level warm air advection keeps tracking eastward into IN. This causes the precip with the system to become a little disjointed as it crosses southern WI overnight. Therefore, highest snowfall rates will be confined to northern IL and possibly far southern WI, the favorable time for this to occur from midnight through 9 am Sun, with western areas having the earliest start and end time compared to eastern areas. Snowfall totals are forecast to range from 1-2 inches toward central WI and 2 to 3 inches toward the IL border. This will cause travel headaches for anyone traveling early Sunday morning. Some areas of southern WI may need a Winter Weather Advisory.

One thing to watch will be a lake effect band that may affect the shoreline of east central or southeast WI early Sunday morning.

Snow will exit by noon Sunday and winds will be a little brisk out of the north. Sunday highs will be around 20.

Cronce

LONG TERM

Issued 310 PM CST Fri Dec 5 2025

Sunday night through Friday:

A lake effect snow band will likely develop along the long axis of Lake Michigan and then may drift into southwest WI Sunday night. It will be a cold night with arctic air overhead, so inland areas will likely drop below zero.

A clipper will cross northern WI on Monday, but this will largely remain north of our area. One more clipper on its heels will also track across northern WI Monday night. This one will have higher precip amounts, and the southern fringe of it may sweep across southern WI Monday night.

The next clipper will track across central WI Tuesday night and exit Wednesday. Accumulating snow is probable but the track is still very uncertain. One more low on the horizon could bring a swath of snow through southern WI or southern IL (or anywhere in between) Thursday afternoon or night.

Cronce

AVIATION

Issued 922 PM CST Fri Dec 5 2025

The last of the snow is making its way through southeastern WI late this evening and should move out over Lake Michigan in the next hour or so. A cold front will continue to work its way through the area into early Saturday morning and will be accompanied by a west to northwest wind shift. Otherwise, widespread ceiling restrictions are expected to continue into Saturday morning bringing widespread MVFR ceilings between 1-3kft and cannot rule out localized, occasional pockets of less than 1kft ceilings at times through day break along with a lingering flurry. Ceilings then are expected to lift through the morning. Then another low is progged to skirt just south of the area, but bring additional round of accumulating snows accompanied by lower visibilities and ceilings to southern WI Saturday night and Sunday.

Wagner

MARINE

Issued 310 PM CST Fri Dec 5 2025

A low pressure trough will cross Lake Michigan this evening and winds will veer to the west and become breezy Saturday morning as high pressure builds in from the west. Breezy northerly winds are then expected Sunday as low pressure crosses IL and the strengthening high pressure reaches Minnesota. Gusts are expected to remain below gales.

Monday night will feature gusty southwest winds with a few gale force gusts possible as low pressure crosses Lake Superior. A low crossing central WI Tuesday night will bring another round of gusty winds and this system may also bring a few gale force gusts.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until midnight Saturday.