textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Mild conditions continue through Tuesday with highs in the low- mid 40s.

- Small chances (~10-25%) for mainly light rain and sprinkles late tonight & Tuesday afternoon.

- Very light round of snow expected (~25-50% chances) Wednesday morning in east-central and southeast Wisconsin.

- Brief warm up on Friday, with conditions trending colder into the weekend with additional chances for light snow.

UPDATE

Issued 932 PM CST Mon Jan 12 2026

No major changes to the forecast this evening. The low pressure system in Manitoba that is going to track east and bring precip to Wisconsin continues to move eastward and clouds are building in from the northwest to the southeast. The diffuse front extending south from the low in Manitoba is roughly between the Dakotas and Minnesota extending south into Iowa and Nebraska. Overcast and dry conditions will continue through the overnight hours as these features continue east.

Patterson

SHORT TERM

Issued 225 PM CST Mon Jan 12 2026

Tonight through Tuesday night:

Synopsis/Mesoanalysis: GOES water vapor imagery shows an upper disturbance over northern Saskatchewan this afternoon. An occluded area of surface low pressure is apparent over north-central Saskatchewan, with a diffuse occluded/warm front extending to its south into the Northern Plains. Moving in tandem with its accompanying upper disturbance, said low will migrate into Ontario tonight, dragging the occluded/warm front into the western Great Lakes. Increasing warm advection ahead of the front, in addition to increasing lift ahead of the approaching upper disturbance, will support light rain and sprinkle potential over east-central Wisconsin during the predawn and early morning hours Tuesday. Mild conditions will continue into Tuesday as the occluded/warm front moves east of the region. A few light sprinkles are possible areawide Tuesday afternoon as low pressure shifts into eastern Ontario & drags a weak wind shift/cold front across southern Wisconsin. A much stronger, Arctic cold front will approach the area late Tuesday night, bringing increasing chances for light snow showers by early Wednesday morning.

Tonight through Tuesday morning: Slight chances (~10-25%) for light rain and sprinkles enter the forecast after predawn. Greatest precip potential will focus near an area of 850-700 mb warm advection, which continues to trend further north in morning & early afternoon forecast guidance. Thus expect that widespread precip will remain over north-central and northeast Wisconsin, though a few light rain showers or sprinkles are possible across the north. Not expecting appreciable accumulation in any activity.

Tuesday night: Light snow chances will begin to trend up after midnight as a stronger Arctic front approaches from the north. Currently expect most light snow to occur after daybreak Wednesday/the beginning of the long term period, though start times could trend earlier. Will continue to monitor arrival time trends in coming forecasts.

Quigley

LONG TERM

Issued 225 PM CST Mon Jan 12 2026

Wednesday through Monday:

Synopsis: An Arctic cold front will either be approaching or crossing southern Wisconsin by sunrise Wednesday, bringing much colder air to the region during the Wednesday-Thursday time frame. Frontogenesis affiliated with the boundary & lift affiliated with an accompanying upper shortwave will support scattered snow showers Wednesday morning, with activity potentially lingering into the afternoon hours in east-central and southeastern Wisconsin. While not expected to be substantial, minor (~dusting) snow accumulation is possible, particularly in east-central and southeast Wisconsin. High pressure will move into the Mississippi Valley on Thursday, vacating east into the Ohio River Valley into Friday. Southwesterly- trending winds will thus support milder high temperatures on Friday. Mean upper troughing will build into the western Great Lakes Thursday night through the weekend, with embedded shortwaves supporting additional periods of snow potential, with additional light accumulation possible. The encroaching upper troughing will be accompanied by a west-northwest wind shift at the surface, resulting in another stretch of chilly daytime highs Saturday through Monday.

Wednesday into Wednesday afternoon: An Arctic cold front will either be approaching or be in the process of moving through southern Wisconsin by daybreak, bringing scattered snow showers. Most deterministic guidance depicts frontogenesis affiliated with the Arctic front shifting south into Illinois by early afternoon, implying that peak/most widespread snow shower potential will be from daybreak through late morning. Could nevertheless see a few lighter flurries/snow showers linger into the afternoon hours amid strong cold advection in the 1000-700 mb layer. Given the fast- moving nature of the front & its affiliated deeper lift, expect snow accumulation to be minor. Latest probabilistic guidance shows low to medium potential (~20-40%) of a dusting, with very low potential (<10%) for totals greater than 1.0". Highest of these readings is across east-central and southeastern Wisconsin. Will continue to monitor trends in the coming forecasts.

Wednesday afternoon through Wednesday night: With persistent northerly flow in place across the western Great Lakes, model guidance continues to hint at possible formation of a north-south lake effect snow band on Lake Michigan. Latest set of forecast solutions has trended this band toward the eastern side of the lake, with most considerable snow accumulations & impacts to the southeast of the area. Current concern for lake effect snow impacts in southeast Wisconsin is thus low in this forecast, though later shifts will continue to watch for any westward shifts in the lake effect band.

Thursday night through Saturday: Mean upper troughing & embedded shortwaves will support additional periods of light snow potential, though deterministic forecast solutions remain in disagreement over the precise evolution of said embedded shortwaves. Loose consensus is evident in the suite of ensemble guidance, and currently points toward Friday morning through Friday night as being most favored for periods of light snow. Will continue to refine peak timing as the week progresses. Could see additional light accumulation in this snowfall, with probabilistic guidance showing medium/high potential (~40-80%) of at least an inch and low/medium potential (~20-40%) of at least two inches.

Quigley

AVIATION

Issued 932 PM CST Mon Jan 12 2026

VFR conditions will persist through Tuesday morning then conditions will deteriorate from north to south as MVFR ceilings around 1.5 to 3 kft move in Tuesday afternoon. These lower ceilings will be accompanied by chances for rain/drizzle Tuesday afternoon/evening then eventually rain/snow mix Tuesday night becoming all snow Wednesday. Not anticipating much of an impact on visibilities through late Tuesday evening as rain chances are low around 10-20% and any rain that develops will be light. Snow potential beyond that TAF period has the highest confidence along Lake Michigan and could potentially bring in some lower ceilings and visibilities how low will depend on whether lake effect snow moves inland.

Light southwest to west winds are expected into Tuesday morning before increasing and becoming breezy west winds. Gusts of 20 to 30 kts will be possible across southern Wisconsin Tuesday afternoon through Wednesday night. There will be a lull in the gusts Tuesday night with a wind shift. The west winds will become northwest then northerly by Wednesday morning.

Patterson

MARINE

Issued 225 PM CST Mon Jan 12 2026

996 mb low pressure is centered over the eastern Hudson Bay this afternoon, resulting in generally west-southwest winds across the open waters of Lake Michigan. High pressure of 1014 mb will cross the waters this evening, bringing a decrease in winds through the first half of the overnight hours. Low pressure of 992 mb will develop near the Ontario-Manitoba border late tonight, deepening to near 988 mb as it approaches the Ontario-Quebec border Tuesday evening. Development and progression of the low will result in increasing west-southwest winds across Lake Michigan early Tuesday morning through Tuesday afternoon. Gusts between 25-30 knots are possible, though gales are not expected at this time.

An Arctic cold front will quickly move south across Lake Michigan late Tuesday night through early Wednesday morning, bringing a gusty north wind shift over the waters. Gale force gusts are anticipated from the late morning hours through early evening, with highest gusts over the southern two thirds of the open waters. A Gale Watch has been issued between 3 AM and 9 PM CST Wednesday over northern Lake Michigan, and between 6 AM CST Wednesday and 12 AM CST Thursday over southern Lake Michigan. Will continue to monitor trends & determine the need for Gale Warnings over the next 12-24 hours. Areas of light to moderate freezing spray will accompany the passing front Wednesday morning through Wednesday evening.

Winds and waves remain below advisory thresholds this afternoon, and will continue to remain below advisory levels through tonight. West- southwest winds will increase ahead of developing low pressure in Ontario on Tuesday. Gusts will likely exceed Small Craft Advisory thresholds during the morning and afternoon hours, with a small decrease anticipated during the evening and first half of the overnight. A cold front will quickly move down Lake Michigan late Tuesday night through Wednesday morning, bringing a gusty northerly wind shift through Wednesday morning. Gales are expected during this time frame. To account for the general increase from Small Craft Advisory to likely gale conditions Tuesday into Wednesday, have thus issued a Small Craft Advisory between 6 AM Tuesday and 6 AM CST Wednesday, with a Gale Watch going into effect between 6 AM CST Wednesday and 12 AM CST Thursday. Will continue to monitor trends & determine the need for Gale Warnings over the next 12-24 hours. Areas of light to moderate freezing spray are expected behind the departing cold front Wednesday morning through early Wednesday evening.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...6 AM Tuesday to 6 AM Wednesday.

Gale Watch...LMZ080-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671- LMZ673-LMZ675-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876- LMZ878...6 AM Wednesday to midnight Thursday.

Gale Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567- LMZ868...3 AM Wednesday to 9 PM Wednesday.