textproduct: Milwaukee/Sullivan

KEY MESSAGES

- A Winter Weather Advisory remains in effect through Monday morning. Light accumulating snowfall is expected this afternoon and evening, with totals around 1 to 2 inches. Gusty northwest winds late tonight into Monday morning will then lead to areas of blowing and drifting snow. Slick spots on pavement and periods of reduced visibility are expected.

- A Cold Weather Advisory is in effect late tonight through Monday morning across all of southern Wisconsin. Bitter cold wind chills of 22 to 29 below zero are expected during this period. Wind chills of 10 to 20 below zero are then expected Monday afternoon into Tuesday morning. - A Gale Warning is in effect for all of Lake Michigan later tonight through Monday afternoon. A Heavy Freezing Spray Warning is in effect as well later tonight through Tuesday morning.

- Accumulating snow is looking likely (55-70% chances) Tuesday night into Wednesday.

- Polar to arctic air (cold temperatures) will prevail through this week and next weekend.

SHORT TERM

Issued 315 PM CST Sun Jan 18 2026

Tonight through Monday night:

Light accumulating snow has begun to fall across the region, and our best guess is that the expected 1 to 2 inch totals (now thru late this evening) are generally on track. We wouldn't be too surprised to see some slightly higher totals in a few spots given how high the snow-to-liquid ratios are with this extremely powdery / fluffy snow. Generally seeing visibility dropouts to around 2 miles at times, with brief periods of around 1/2 mile. The Winter Weather Advisory does cover this phase of the event, but the primary window of "Advisory level conditions" will actually occur after the snow winds down late tonight.

An arctic cold front crosses the region this evening, with strong northwest winds (30 to 40 MPH gusts) behind it. These gusty winds, arriving around or after midnight tonight, will lead to areas of blowing and drifting snow. Broken low-altitude clouds will linger tonight and tomorrow morning and could even produce a few flurries, but the main story will be the bitter cold wind chills (air temps around or just below zero, wind chills of 22 to 29 below zero), slick spots on pavement due to drifting snow, and areas of reduced visibility due to blowing snow. All of these are expected to impact AM travel, hence we have both a Winter Weather Advisory and Cold Weather Advisory in effect. Both are set to expire mid day Monday as the northwest winds begin to gradually decelerate.

Dry weather expected Monday and Monday night. Daytime high temps in the single digits above zero, lows in the single digits below zero. Wind chills through this period will be 10 to 20 below zero.

Sheppard

LONG TERM

Issued 315 PM CST Sun Jan 18 2026

Tuesday through Sunday:

Polar or arctic air will prevail during this period.

A weak surface ridge will pass Tue into early Tue evening with cold temps continuing. A shortwave trough will then track from the nrn high plains to srn WI and nrn IL by 12Z Wed. A wave of low pressure will accompany this feature and track across nrn IL into lower MI with some differences on this track among the models. A nose of 50 kt low level jet will support low to mid level warm advection and frontogenesis supported aloft by PVA and warm advection at the jet level. A narrow west to east band of several inches of snow will be possible whether its in srn WI or nrn IL. Areas of light snow may then linger into Wed.

Modest cyclogenesis will be underway over the nrn Great Lakes for Wed-Wed nt while another shortwave trough approaches from the nw and tracks across srn WI Wed nt along with a wave of low pressure and cold front. These features also differ in strength among the models with only small chances for light snow forecast at this time, but trending higher. Wly winds and cold advection will continue into Thu.

From Thu into Fri a large upper low will move into wrn Ontario from central Canada then shift ewd into Quebec. It trailing trough axis will force a strong arctic front across srn WI Thu nt with frigid conditions to follow. A 1045 mb high may shift ewd across the region Fri nt-Sat with a lingering sfc ridge into Sat nt. This frigid air mass will likely be the coldest of the season and possibly in years. Stay tuned!

Gehring

AVIATION

Issued 315 PM CST Sun Jan 18 2026

Light to briefly moderate accumulating snow continues this afternoon and evening, with totals in the ballpark of 1 to 2 inches. Periods of IFR visibility to 2 SM (briefly down to 1/2 SM) are expected at times, with cloud ceilings predominantly MVFR around 1,000 to 3,000 ft. Light southwesterly surface winds accompany the snow, with a brief intensification of the snow possible as an arctic cold front crosses the region this evening.

Behind this front (around or after midnight tonight), strong northwesterly winds with gusts of 30 to 35 KT arrive, leading to areas of blowing and drifting snow, with pockets of reduced visibility (the Winter Weather Advisory was issued primarily for the blowing snow phase of the event). Low ceilings gradually scatter out around or after dawn Monday morning, and areas of blowing snow persist until around midday (when northwest winds gradually decelerate). Low clouds do linger into the afternoon, but our best guess is scattered coverage.

Sheppard

MARINE

Issued 330 PM CST Sun Jan 18 2026

Low pressure will deepen to 29.5 inches over the northern Great Lakes by sunrise Monday and sweep an arctic front across the lake after midnight tonight. Northwest gales will develop and last through Monday afternoon with a Gale Warning in effect, while a Heavy Freezing Spray Warning will also go into effect and last through Tuesday morning.

High pressure around 30.5 inches will shift across the southern and eastern portion of the country for Tuesday into Wednesday, supporting modest west to southwest winds over Lake Michigan. A couple more cold frontal passages will bring a return of brisk west to northwest winds for later Wednesday through Friday. Heavy freezing spray may also return.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory...WIZ046-WIZ047-WIZ056-WIZ057-WIZ062- WIZ063-WIZ067-WIZ068-WIZ069 until noon Monday.

Cold Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056- WIZ057-WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065- WIZ066-WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...3 AM Monday to noon Monday.

Winter Weather Advisory...WIZ051-WIZ052-WIZ058-WIZ059-WIZ060- WIZ064-WIZ065-WIZ066-WIZ070-WIZ071-WIZ072 until noon Monday.

LM...Gale Warning...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.

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

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