textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy dense fog may redevelop tonight especially over south central WI.

- Mild temperatures and rain on Sunday will transition rapidly to snow as temperatures drop below freezing Sunday night. Expect widespread accumulations between 1-2 inches through Mon AM, but areas near central Wisconsin may see as much as 3 inches.

- Polar air returns Sunday night and continues through the end of next week, with temperatures remaining at or below normal. - Northwest gales are likely for all of Lake Michigan Sunday night into Monday evening, but cannot rule out storm force gusts either.

SHORT TERM

Issued 245 PM CST Fri Dec 26 2025

Tonight through Monday night:

A weak sfc ridge will pass late tnt into Sat AM but overall the stratus will likely persist. Where the stratus does thin, there will be a greater potential for fog, possibly dense.

Sly winds and warm advection will ensue for Sat as weak high pressure moves away and low pressure tracks from the nrn high plains to the central high plains. This is in response to a wrn upper trough approaching the Rockies. There may be a higher tendency toward breaking up the stratus in the afternoon but high clouds will also increase. Relatively mild temps will continue.

The wrn upper trough will comprise of a shortwave trough tracking along the US/Canadian border reaching the ern Dakotas by 00Z Mon, while another shortwave trough is farther to the south, reaching the central Great Plains by the same time. The sfc low will be over ern KS at 12Z Sun with an inverted trough extending through WI. Very light rain or drizzle may develop (30-50% chance) late Sat nt through Sun AM via the low level warm, moist advection.

The ECMWF Ens and the GEFS and their 12Z deterministic runs are now deepening the low as it approaches the wrn Great Lakes with rapid deepening Sun nt when it tracks from far srn Lake MI around 995 mb to around a 980 mb low over nrn Lake Huron for Mon AM. Greater QG lift and PWATs increasing to an inch has resulted in rain and snow chances increasing to 60-80% from Sun afternoon into Mon AM. As the low passes, the main tropospheric temperature gradient and potential frontogenesis shifts through the area ahead of the approaching and amplifying upper trough from the west. Brisk nwly winds and cold advection will ensue during this time with rain changing over to light snow Sun nt then lingering into Mon AM over ern WI. Snow accums of 1-3 inches are now fcst with the higher totals toward central WI. Nwly wind gusts could reach 40-45 mph via the bombogenesis. Winter Wx Advisories or Wind Advisories may be needed over portions of srn WI. Low temps will drop into the teens by sunrise Mon with high temps in the upper teens to middle 20s. Single digit below zero wind chills to single digit above zero wind chills are forecast during this time. Decreasing nwly winds are likely Mon nt with lows from 7 to 13 above.

Gehring

LONG TERM

Issued 245 PM CST Fri Dec 26 2025

Tuesday through Friday:

No major changes to the extended forecast today. Colder conditions are still on track Tuesday through Friday as northwest flow takes hold behind Monday's trough. A couple modest clipper systems still remain possible Tuesday and then Wednesday night into Thursday though ECMWF and GFS solutions vary on the track, particularly for the Wednesday/Thursday system.

The Tuesday system looks to be a glancing blow of light QPF north of I-94, while the Wednesday night system looks to give us a better shot at an inch or two of accumulation over much of the area if solutions align with the current runs of the GFS. Trends will be monitored. Given highs in the teens to 20s, both systems will likely bring light snow, rather than any mix or rain. The NBM has greatly massaged PoPs to be 20% or less for both systems today given the more nebulous agreement from long range guidance. Still, given the consistent signal for the shortwaves from the global models, the potential remains for the clippers with today's long-term forecast.

CMiller

AVIATION

Issued 245 PM CST Fri Dec 26 2025

Cigs will waver from just above or just below 1 kft this afternoon and evening. But Cigs will mainly drop below 1 kft once again late tnt. Vsbys of 1/2-1SM via FG or BR will redevelop over south central WI with local 1/4SM FG possible. Vsbys over ern WI will range from 2-5SM BR. These vsbys will not improve until late Sat AM. There is then much uncertainty whether the low stratus clouds will persist into Sat afternoon or dissipate.

Gehring

MARINE

Issued 245 PM CST Fri Dec 26 2025

Light to modest northwest winds will become established across Lake MI this afternoon and early evening. High pressure around 29.9 inches then moves across the lake late tonight into Saturday morning, with light and variable winds.

Modest southeast winds will then return by midday Saturday and continue through Sunday morning as low pressure develops over the central Great Plains. Low pressure then deepens to 29.4 inches Sunday evening as it tracks across far southern Lake MI, then deepens to 28.9 inches over northern Lake Huron Monday morning. The strong low will then reach far southern Quebec by late Monday. Confidence is high in northwesterly gale force winds late Sunday night through Monday night with some potential for storm force gusts on Monday. A Gale Watch is now in effect. Much colder air will also bring moderate freezing spray throughout this time frame.

A Small Craft Advisory may be needed from Sheboygan to Winthrop Harbor Saturday night as waves build on persistent sely winds.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. 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 AM Tuesday.