textproduct: Marquette

KEY MESSAGES

- Lake effect snow showers will continue today, focusing into the Keweenaw Peninsula. Snowfall may increase in intensity in and north of Houghton beginning near today's afternoon commuting period and tonight. Winter Weather Advisories were extended through Wednesday morning.

- Very cold conditions and elevated winds will create wind chills of -20 to -35F to the area this morning. A Cold Weather Advisory into this morning.

- Coldest air of the season will create a period of below zero temperatures from Thursday night through at least Saturday morning across most of Upper Michigan. Temperatures below -15F and wind chills near -35F are likely (50-70% chance).

DISCUSSION

Issued at 204 AM EST Tue Jan 20 2026

Broad long wave trough stretching south from Hudson Bay has allowed a cold airmass to settle over the area tonight. This airmass is supporting 3 hazards across Upper Michigan: first are surface temperatures below zero for most of the region and even below -10F in parts of the interior west half; second, the cold air combined with lingering elevated pressure gradient forces are creating dangerously cold wind chills. Latest wind chill calculation at KIWD is -28F and KESC is -30F; and third, the cold air being atop a mostly ice free Lake Superior is supporting enough moisture flux and instability to support lake effect snow showers across the west, Keweenaw Peninsula and eastern Upper Michigan, with a dominate banding structure observed moving into KCMX and eastward into eastern Alger/Luce counties, aided by land breeze coming off the Michigamme Highlands. The cold air is allowing for very fine flakes, which in addition to notable accumulations, are creating very low visibility due to their susceptibility to blow in the wind. As the night progresses, these 3 hazards will continue and inherited Winter Storm Warnings in Alger/Luce, Winter Weather Advisories in Gogebic, Ontonagon, Northern Houghton, and Keweenaw counties, and forecast area-wide cold weather advisories are on track.

Today, daytime temperatures will warm into the single digits above zero for most of the region, with a few spots by Lake Superior climbing to near 10F. Winds will weaken some, but elevated winds of 20+ mph in the Keweenaw Peninsula and by Lake Superior are expected to persist. While we will warm above Cold Weather Advisory criteria, hazardous conditions from the cold will persist through the day given that wind chills below -10F will continue into at least the mid-afternoon hours for most of the forecast area. Winds will remain mostly westerly in the Keweenaw and westerly to southwesterly elsewhere, supporting convergent snow banding structures lifting north through Ontonagon County this morning into Houghton County and showers in Alger/Luce lifting offshore by afternoon. Latest CAMS suggest the band increase in intensity near that PM commuting period in Houghton proper before lifting north of Houghton this evening. Given the continued blowing snow risk from elevated winds and an additional 4 to 6 inches through Wednesday morning from Houghton to Copper Harbor, opted to extend the inherited Winter Weather Advisories in the Keweenaw to 12z Wednesday. Will let the other headlines expire at 12z as originally planned.

To the south this evening, a weak wave will press through Wisconsin while another clipper drops into the Upper Great Lakes. The system to the south will maintain the better forcing south of the forecast area, but can't rule out light snow spreading north into the south- central Wednesday morning. Should this occur accumulations should amount to less than half an inch. The incoming clipper looks to support a deepening surface low over Lake Superior by Wednesday afternoon, enhancing lake effect and dominate banding structures, perhaps allowing meso lows for form. By Wednesday night, the surface low pulls away and surface troughing lingers westward across Lake Superior, supporting continued lake effect snow showers into the traditional lake effect snow belts. While this occurs, very cold air will wrap around into the Upper Great Lakes while a strong pressure gradient reestablishes itself. The airmass building in will be the coldest one of the season so far, on the order of -30 to -35C at 850mb. The increasing pressure gradient will also support winds near 10 mph in many locations, with gusts climbing to 20-30 mph Wednesday night into Thursday, allowing wind chills to fall to -15 to -20F in the interior west. Highs on Thursday will only peak near zero in the interior west, and low to mid single digits above zero elsewhere. Beginning Thursday night, overnight lows of -10 to -25F are expected for a majority of the forecast area, with highs Friday ranging from - 10F to near zero. The cold will continue into Saturday when we see the first chance of potentially warming above zero maybe on Saturday. Cold Weather Advisories look certain for most if not all the forecast area, with potential for Extreme Cold Weather Warnings.

While the forecast pattern of northwest flow aloft persists thereafter, timing of shortwaves is uncertain. At this point, guidance suggests lake effect in the Keweenaw and in eastern Upper Michigan may ease sometime Saturday as high pressure over Wisconsin builds into the region before potentially returning Sunday into Monday.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 601 AM EST Tue Jan 20 2026

As the winds become progressively more westerly and eventually southwesterly today and tonight, expect generally VFR conditions over SAW and IWD over the next 24 hours. However, with lake effect snowfall and BLSN continuing over CMX, expect the low MVFR cigs and IFR to LIFR vis to continue, especially this afternoon as the lake effect band begins to intensify. However, as the band moves further north with time this evening into the overnight hours, expect CMX to improve.

Could see some MVFR cigs for an hour or two at IWD this morning. However, with satellite imagery showing clear skies overhead and winds already becoming more southwesterly, don't think that this is likely (30% or less chance to occur). Could also see a return to MVFR conditions at IWD late tonight too, but uncertain on these chances as it will depend on how two disturbances interact with one another this evening.

MARINE

Issued at 204 AM EST Tue Jan 20 2026

Winds near 30 knots from the west or southwest are expected to continue today and tonight, with the strongest winds, potentially with some gale force gusts across the east. These lighten to near or below 20kts by Wednesday morning. Another elevated wind period returns Wednesday night, persisting into at least Saturday morning. Gales can't be ruled out, especially Thursday when overlake instability peaks from the incoming very cold airmass.

The risk for heavy freezing spray will continue today and tonight due to the cold air over the area and the elevated winds. Conditions improve Wednesday under the light winds, but return Wednesday night and continue into at least Saturday morning.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Cold Weather Advisory until 9 AM EST this morning for MIZ001- 003.

Winter Weather Advisory until 7 AM EST Wednesday for MIZ001- 003.

Winter Weather Advisory until 7 AM EST /6 AM CST/ this morning for MIZ002-009.

Cold Weather Advisory until 10 AM EST /9 AM CST/ this morning for MIZ002-011>013-084.

Cold Weather Advisory until 11 AM EST /10 AM CST/ this morning for MIZ004>007-009-010-014-085.

Winter Storm Warning until 7 AM EST this morning for MIZ006- 007-085.

Lake Superior... Heavy Freezing Spray Warning until 10 PM EST /9 PM CST/ this evening for LSZ240>244-263-264.

Heavy Freezing Spray Warning until 1 AM EST Wednesday for LSZ245>250-265-266.

Heavy Freezing Spray Warning until 7 AM EST Wednesday for LSZ251-267.

Lake Michigan... None.