textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Winter Weather Advisory remains in effect until 9 PM in southeast Wisconsin.

- 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. We are expected to reach Cold Weather Advisory criteria (wind chills 20 degrees below zero) Sunday night into Monday morning.

- Light accumulating snow is expected Sunday afternoon into Sunday night, with new accumulations around 1 to 2 inches across the region. Gusty northwest winds Sunday night into Monday may lead to some areas of blowing snow. Watch for slick spots and pockets of reduced visibility.

- A Gale Watch is in effect for Lake Michigan late Sunday night through Monday, with a Heavy Freezing Spray Watch late Sunday night through mid day Tuesday.

UPDATE

Issued 840 PM CST Sat Jan 17 2026

Forecast remains largely on track this evening. Steady snows have concluded across the western half of the area, where the Winter Weather Advisory was allowed to expire at 6 PM CST. Further east, steady snows continue, albeit at tapering hourly rates. Activity is ongoing within a band of 925-850 mb frontogenesis & warm advection, with model analyses from the RAP showing the forcing & most favorable DGZ depths shifting southeast. Said shifts likely explain the tapering rates in east-central and southeast Wisconsin. Expect these trends to continue near-term, with the remainder of the Winter Weather Advisory on track to expire at 9 PM CST.

Further west, a pronounced surface ridge is evident from Minnesota into the Missouri Valley. Light radar returns are apparent along the leading periphery of the ridge, and are likely being driven cold advection & weak frontogenesis at the 925 mb level. Have noted reports of flurries within these echoes, though reports have been sporadic as dew points fall into the single digits along the leading edge of the ridge. Have reflected these trends in the near term grids (now through 1 AM) with 10-30% precip probs, with the expectation that arriving very dry air will shut activity off during the predawn hours. Will continue to monitor trends and make adjustments if necessary. Not anticipating impacts in any flurry activity through the late evening hours.

Quigley

SHORT TERM

Issued 320 PM CST Sat Jan 17 2026

Tonight and Sunday:

Surface to 850mb FGEN continues to drive some light to moderate accumulating snow across southern WI this afternoon. A Winter Weather Advisory remains in effect into this evening for portions of the region, expiring in a west to east manner, with additional accumulations up to around 1 to 1.5 inches and short periods of 1/2 mile visibility. As seen in the surface wind fields, a gradual re-centering of the FGEN (and associated moderate snow rates) to far southeastern WI is expected (and ongoing based off of 3:20 PM radar composite images), moving out over Lake Michigan by around 9 PM CST this evening. Some off/on flurries may linger for several hours after the accumulating snow ends.

Dry weather is expected late tonight into Sunday morning, with another batch of accumulating snowfall from Sunday afternoon into Sunday night. Totals around 1 to 2 inches expected with this second batch. Winds and gusts should remain less than or equal to 20 MPH through the daytime hours of Sunday, with daytime high temperatures in the mid to upper teens expected. As such, the wind chill temperatures should be in the single digits above/below zero through much of this timeframe. That all changes late Sunday night as the arctic front arrives.

Sheppard

LONG TERM

Issued 320 PM CST Sat Jan 17 2026

Sunday night through Saturday:

A fairly strong shortwave trough will quickly swing sewd from the Dakotas to the MS River by 00Z Mon, then across srn WI and nrn IL Sun evening. Cyclogenesis will be ongoing over the nrn Great Lakes during this time with the trailing arctic front to move across srn WI as well. Weak low to mid level warm advection will give way to PVA, low to mid level frontogenesis, and cold advection with the strong arctic front. QPF values of 0.10 inches or less are forecast with high liquid to snow ratios yielding 1-2 inches.

The greater concern is the increasing wind fields late Sun nt into Mon AM and blowing snow potential. Nwly wind gusts of 35-40 mph and several inches of powdery snow depth may necessitate a Winter Wx Advisory for blowing snow. In addition, A Cold Weather Advisory will likely be needed as early as Mon AM as wind chill temps plummet to 20 below to 29 below zero, while air temps plummet to 5 below zero to 3 above zero by sunrise Mon AM. The Cold Weather Advisory would continue at least through the morning but may be needed through the day and into Mon nt. This will be due to air temps only rising to 2-6 above zero for the day while brisk winds continue.

The winds will become light for late Mon nt and Tue when a weak sfc ridge moves across srn WI. A series of shortwave troughs in nwly flow aloft will then traverse the region into Thu. A round of swly winds and warm advection ahead of one of the upper waves may bring likely (60% chance) snows to srn WI for Tue nt lingering into Wed. For late in the week the jet stream attempts to return to zonal flow with warm advection bringing 20 percent chances for light snow. Polar to arctic air will remain over srn WI for much of the week.

Gehring

AVIATION

Issued 840 PM CST Sat Jan 17 2026

Largely MVFR flight categories prevail this evening as -SN begins to taper across southern Wisconsin. Expect reduced flight categories to continue into the overnight hours. Will be monitoring light flurries currently being reported to the west of I-39 for possible additions through the late evening hours. High pressure will move into the region closer to daybreak, resulting in weakening winds. Whether the high's arrival will bring VFR conditions remains uncertain. Have brought VFR flight categories into the forecast at KMSN and KJVL, and maintained MVFR categories further east. Will continue to monitor trends. The high will move east tomorrow afternoon, allowing southwest winds to become established. Another disturbance is forecast to move into the western Great Lakes later tomorrow afternoon and evening, bringing additional chances for -SN to all terminals nearing the end of the period. Will continue to refine -SN mentions in the coming 03Z and 06Z updates.

Quigley

MARINE

Issued 320 PM CST Sat Jan 17 2026

Low pressure around 29.7 inches will continue to move away across southern Quebec tonight with a trailing cold front moving across Lake Michigan. Modest to brisk west to northwest winds are expected.

Another low pressure system around 29.9 inches will track from northwest Minnesota Sunday morning to slowly across the northern Great Lakes through Monday and deepen to 29.6 inches as it does so. An arctic front will then move across the lake early Monday morning with northwest gales and heavy freezing spray possible. A Gale Watch is in effect for all of Lake Michigan from early Monday morning and through the day. A Heavy Freezing Spray Watch is in effect from early Monday morning through Tuesday morning. Westerly winds will then gradually weaken Monday night and Tuesday.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...Winter Weather Advisory...WIZ059-WIZ060-WIZ064-WIZ065-WIZ066- WIZ069-WIZ070-WIZ071-WIZ072 until 9 PM 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.

Heavy Freezing Spray Watch...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 Watch...LMZ643-LMZ644-LMZ645-LMZ646...midnight Monday to noon Monday.