textproduct: Milwaukee/Sullivan

KEY MESSAGES

- A Winter Weather Advisory remains in effect until 9 AM CST this morning for the Highway 18 and Interstate 94 corridor area, for a narrow band of moderate to heavy snow. Snowfall rates of one half to one inch per hour are possible in this band. This band should shift slowly southward later today and exit to the southeast this evening. Snow covered and slippery roads are expected.

- Light snow is expected Sunday afternoon, exiting to the southeast Sunday night.

- Below normal temperatures are expected this weekend through the early part of next week. The coldest temperatures and wind chills are expected Sunday night through Tuesday. Cold Weather Advisory criteria (wind chills 20 degrees below zero) may be met or exceeded Sunday night into Monday morning.

- A Gale Watch is in effect for Lake Michigan later Sunday night into Monday. Building waves and cold temperatures will bring freezing spray Sunday night into Tuesday, with some heavy freezing spray possible.

SHORT TERM

Issued 456 AM CST Sat Jan 17 2026

Today through Sunday night:

The narrow band moderate to heavy snow continues to meander and morph slowly over the Highway 18 and Interstate 94 corridor early this morning. The heaviest snow is currently over northern Milwaukee and northeast Waukesha Counties, with mainly light snow elsewhere in the Winter Weather Advisory area. Snow rates of one half to one inch per hour are expected with this narrow band, with rates of one quarter inch per hour or less elsewhere. 1 to 2 inches of additional snow accumulation is forecast for the advisory area at this time.

This band has been driven by 850 mb to 700 mb frontogenesis response from a slowly moving trough in this layer. The narrow snow band has been essentially quasi-stationary this evening into the overnight hours, though it has recently been reduced to the current affected area. Forecast soundings are also showing a deep and saturated dendrite snow growth zone from overnight lingering into today. This snow band has been quite difficult to forecast, and there is some uncertainty with what may occur with this band into today.

CAMs and other models suggest that this band may linger across the advisory area into this morning, before slowly shifting southward this afternoon and southeast of the area by early to middle evening. Continued monitoring will be needed to see if this narrow heavy snow band will redevelop or will become more light snow into this morning, and if the current advisory needs any extension in time and/or expansion to the south.

Another Arctic cold front shifting southeast through the region this evening would help shift this snow out of the area. Thus, have kept light snow in the forecast with high probabilities (80 to 100 percent) today before exiting southeast by middle evening. CAMs have some possible convective snow showers shifting southeast but missing northeast parts of the forecast area this evening. This may need some watching, as the snow squall parameter is over one to the northeast of the area. Again, most of this activity should remain to the northeast.

Another period of light snow is expected Sunday afternoon, exiting to the southeast Sunday night, with warm air advection and deep moisture combining with a cold frontal passage and some differential CVA passing through. Forecast soundings show steep low level lapse rates with saturation in the dendrite snow growth zone during this period.

For now, have another period of high probabilities for light snow (70 to 90 percent) Sunday afternoon. Snow rates should generally be around one quarter inch per hour or less, with light QPF and high snow to liquid ratios allowing for snow accumulations of 1 to perhaps up to 2 inches possible.

Cold lows in the single digits above zero are expected tonight, with wind chills in the single digits below zero. Wind chills should dip to or below 20 below zero Sunday night into Monday morning, and a Cold Weather Advisory may be needed for the entire area. Lows Sunday night should drop below zero for most of the area with the fresh snow cover.

Wood

LONG TERM

Issued 456 AM CST Sat Jan 17 2026

Monday through Friday:

Bitterly cold conditions will continue through the day Monday, with temperatures struggling to get much above zero. Additionally, winds gusting 25 to 30 MPH will result in the wind chills of 20 below to 25 below zero early morning, only improving to 10 below to 20 below zero by the afternoon. Though below zero temps are expected Monday night, winds will be lighter as high pressure slides by to the southwest, resulting in wind chills remaining in the 10 below to 20 below zero range.

Dry weather is likely Monday into Tuesday, with a shortwave possibly brining snow chances back to the area Tuesday night into Wednesday. Temperatures will be a little milder mid-week, though likely remaining below normal. Colder conditions are then expected to return late week into the weekend, along with light snow chances.

DDV

AVIATION

Issued 456 AM CST Sat Jan 17 2026

The narrow band moderate to heavy snow continues to meander and morph slowly over the Highway 18 and Interstate 94 corridor early this morning. The heaviest snow is currently over northern Milwaukee and northeast Waukesha Counties, with mainly light snow elsewhere in this area. Snow rates of one half to one inch per hour are expected with this narrow band, with rates of one quarter inch per hour or less elsewhere. 1 to 2 inches of additional snow accumulation is forecast for the Madison, Waukesha and Milwaukee terminals.

This snow band has been quite difficult to forecast, and there is some uncertainty with what may occur with this band into today. It may linger this morning, before slowly shifting southward this afternoon and southeast of the area by early to middle evening. Continued monitoring will be needed to see if this narrow heavy snow band will redevelop or will become more light snow into this morning.

Ceilings have been varying widely between VFR and around 1000 feet AGL, and should generally become 1000 to 2000 feet AGL today into tonight, before rising above 3000 feet AGL later tonight. Visibility has also varied widely, from 6 miles or more in light snow or snow free areas to 1/2 to 3/4 mile in the heavier snow bands. A general 2 to 5 mile visibility in light snow is anticipated into today, before improving tonight as the snow exits the area. Locally lower values may occur with heavier snow bands. Gusty west winds are generally expected today into tonight.

Some snow showers shifting southeast should miss the Sheboygan terminals this evening, but may need some watching.

Wood

MARINE

Issued 456 AM CST Sat Jan 17 2026

Low pressure around 29.3 inches will move into eastern Ontario today. Gusty west winds are expected over southern portions of the lake, with lighter winds to the north. Winds should become more northwest tonight, as a cold front shifts southeast across the lake.

A Small Craft Advisory has been extended through today south of Port Washington, for gusty west winds.

Another low pressure system around 29.7 inches will track from northwest Minnesota into Lake Superior Sunday afternoon and evening. Winds will turn to southwest to west and increase ahead of this system. A few gusts may approach gale force Sunday afternoon and evening.

A cold front will move across the lake late Sunday evening, causing winds to become west to northwest and strengthen. High pressure around 30.5 inches will move into the central Plains Monday, helping sustain the strong winds.

Gales are likely later Sunday night into Monday, with a Gale Watch in effect for all of Lake Michigan. Building waves and cold air moving into the region will bring a period of freezing spray Sunday night into Tuesday. Some heavy freezing spray is possible during this period.

The Gale Watch is in effect for the nearshore waters of Lake Michigan as well later Sunday night into Monday morning. A Small Craft Advisory will be needed Sunday afternoon into Sunday evening, with another Monday into Monday evening, for gusty winds. Freezing spray may occur.

Winds will weaken and shift west to southwest Monday night into Tuesday night, ahead of another low pressure system around 29.9 inches shifting from Alberta towards the Great Lakes.

Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory...WIZ056-WIZ057-WIZ058-WIZ059-WIZ060- WIZ062-WIZ063-WIZ064-WIZ065-WIZ066 until 9 AM Saturday.

LM...Gale Watch...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...midnight Monday to 6 PM Monday.

Gale Watch...LMZ643-LMZ644-LMZ645-LMZ646...midnight Monday to noon Monday.

Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 6 PM Saturday.