textproduct: Marquette

KEY MESSAGES

- Confidence continues to increase on an impactful winter weather event late Tuesday into Thanksgiving. Chances of 12 inches or more of snow are over 90 percent across the western UP by Thanksgiving.

- Wind gusts of 25-35 mph are expected Wednesday, with some gusts to 45 mph or more possible over the Keweenaw. The combination of wind and moderate to heavy snowfall could make holiday travel very difficult to near impossible at times.

- Gales up to 45 kt are expected (70-90%) on Lake Superior Tuesday night through Thursday, with a 30-40% chance for Storm-force gusts. Wave heights of 12-18 ft are expected, with some spots near the tip of the Keweenaw and between Marquette and Grand Marais seeing up to 16-19 ft waves.

DISCUSSION

Issued at 324 AM EST Mon Nov 24 2025

Some mid-level clouds are hanging out over the Upper Peninsula early this morning as sfc ridging gives way to a lower-level troughing pattern today. However, with model soundings showing a robust dry layer below 8 kft, no precipitation is expected to hit the ground today; if anything does, expect only light drizzle at the utter most. If you've got any last minute fall projects that need to be done, today is the day to do it as the weather looks to be pleasant, with highs once again creeping up into the 40s to potentially even lower 50s as south to southwesterly winds blow throughout the day.

The quiet part of the forecast period ends this evening as two shortwave lows, one moving through the Northern Plains and another lifting through the Southern Plains, phase with one another over the Upper Mississippi Valley on Tuesday. As this occurs, light rain begins to creep into the southern half of the U.P. tonight, with rainfall picking up slightly and overspreading the rest of Upper Michigan Tuesday. Overall, not much rainfall is expected tonight through Tuesday as the shortwaves are not expected to be synoptically deep; thus, synoptic-scale forcing associated with the warm frontal ascent will be somewhat limited and keep things on the lighter side. That being said, the NBM ensemble suggests that anywhere in the U.P. has a 40 to 70% chance of seeing at least a quarter inch of precipitation between tonight and Tuesday evening, which would produce at least a wetting rainfall across portions of the Upper Peninsula.

The 'headliner' so-to-speak for this forecast period is the snowfall, which is expected to start accumulating over the western U.P. Tuesday evening as temperatures finally cool to and below freezing. However, as the phasing of the lows occur Tuesday over the Upper Mississippi Valley, improving synoptic-scale forcing over the western U.P. could induce dynamic cooling within the profile, causing the rain to switch over to snowfall earlier in the day; snowfall could start accumulating as early as early Tuesday afternoon (see the 00z NAM3km and GFS for examples). However, confidence on this happening is still rather low at this time, as this will still be during the daylight hours and could be affected by the timing and track of the phasing shortwave lows. However, confidence on the transition over to snowfall over the western U.P. increases Tuesday evening as the now-almost-completely phased low starts to deepen. With warm air advection continuing to pump Gulf moisture into the low pressure system Tuesday night and Wednesday over the central and eastern U.P., current guidance has a potential TROWAL developing over the Keweenaw and western U.P. Tuesday night into Wednesday as cold air north and behind the low moves over the western third of our CWA, with the cold air advection progressing eastwards with time Tuesday night through Wednesday as the low lifts towards Canada. As the TROWAL looks to generally remain settled over the Keweenaw and west Tuesday night into Wednesday, expect several hours of moderate to heavy accumulating snowfall. In addition, expect the winds to increase with time Tuesday night through Wednesday across all of Upper MI, creating a blowing snow threat too, especially as the snowfall transitions to lake enhanced and eventually pure lake effect Wednesday into Wednesday night. The high snowfall rates and lower visibilities due to the blowing snow potential could make travel very difficult to downright dangerous at times, especially over the western U.P. and the Keweenaw where the greatest snowfall amounts are expected; up to 12 inches of snowfall is almost guaranteed across the western U.P. between Tuesday night and Thursday morning according to the NBM (90+% chance). Therefore, a Winter Storm Watch has been hoisted up for Gogebic, Ontonagon, Houghton, Baraga, and Keweenaw counties to account for the potentially significant snowfall and dangerous travel conditions.

As the low begins to lift away towards northern Quebec later Wednesday, expect the transition over to lake enhanced snowfall across the rest of the U.P. from west to east as the TROWAL slowly starts to slide eastward with the low. While some snowfall could be seen in the south central areas, expect accumulations to limited to a couple of inches as the more impactful snowfall falls closer to (and just uphill from) Lake Superior. With the lake waters being at around 5 to 6 C before this event, the stronger winds off of the lake may bring the warmer air over the waters to the immediate nearshore, limiting snowfall amounts in areas like Ontonagon, Copper Harbor, Baraga/L'Anse, Marquette/Harvey, and Munising proper (not up in the hills). However, with the strongest winds expected near the lakeshore, expect the greatest blowing snow impacts to be seen in and around these areas (like M-28 from Marquette to Munising) once the snow starts to stick. Given the strong winds, even as we transition to pure lake effect snow from the northwest wind snow belts late Wednesday into Wednesday night/Thursday, expect the snow ratios to not be too much higher than 10:1; thinking they will range from the lower to mid teens as snowflakes have a higher chance of fracturing in the high winds. Nevertheless, some spots may see higher snow ratios of 20+:1 at times as the inversion heights within some of the lake effect bands could get up to 10 kft or greater(!), with forcing maximized in the DGZ. While the chance is not high, thinking the NBM is correct to produce a 10% chance for thundersnow over the eastern lake Wednesday night given that some small amounts of MUCAPE are being seen within the model guidance. Thus, while they look to miss out on the TROWAL over the western U.P. Tuesday night, the northwest wind snow belts as well as northern Marquette County could see moderate to heavy lake enhanced to lake effect snowfall at times Wednesday into Thursday; don't be surprised if additional Winter Weather Headlines are issued for these areas in the future.

Northwest lake effect snowfall continues across the region through the Thanksgiving holiday into Friday and potentially even Saturday too. While the lake effect snowfall and blowing snow is expected to not be as bad on Thanksgiving as it will be Tuesday night through Wednesday, we could still see some moderate to occasionally heavy lake effect snow bands over the northwest wind snow belts from time to time on Thursday, with blowing snow occasionally reducing visibilities further along and near the Lake Superior shoreline. As the troughing and cold core aloft weaken over us late this week, expect the lake effect snowfall over the northwest wind snow belts to lighten up, potentially even ending over the west half by late Friday. Given the larger fetch, however, it looks like lake effect snow will continue over the east at the very least until this weekend.

The colder than normal temperatures look to continue across the area into early next week as polar air plunges towards the Desert Southwest. While predictability is low at this time, we may see a shortwave or two bring accumulating snowfall back across the area sometime late this weekend and/or early next week as Gulf air tries to push northwards against the polar air.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1234 PM EST Mon Nov 24 2025

VFR conditions and mostly light winds are expected at all sites today. Tonight, lowering cloud bases with eventual ceilings at MVFR are expected as a system lifts abundant moisture into the area. By morning, all sites are expected to be IFR with rain moving into KIWD and possible KSAW. KSAW could dip to LIFR and a prob30 group was included. Although not included in the TAF, low ceilings and visibilities will continue through the day Tuesday.

MARINE

Issued at 340 AM EST Mon Nov 24 2025

As weak troughing moves over the Upper Great Lakes today, expect the south to southwest winds of 20 to 25 knots over the western and eastern lake to continue until late this afternoon, with gusts up to 30 knots possible over the far eastern lake late this morning. While we can expect a short reprieve in the winds this evening, expect the winds to begin picking back up over the western half of the lake starting Tuesday as two shortwave lows, one moving over the Northern Plains and the other lifting from the Southern Plains, phase with one another over the Upper Mississippi Valley. This will cause winds to increase from the northeast throughout the day, eventually bringing northeast gales up to 35 knots to the western lake by Tuesday evening. As the nearly-phased low continues towards Lake Superior Tuesday night, expect the winds to slowly become more northerly with time as the gales increase to 45 knots; a few storm- force gusts up to 48 knots, while not expected could be seen from time to time (30 to 40% chance according to the NBM). In addition, waves will begin to swell to 12 to 16 ft across the western half of the lake. As the low moves through Lake Superior on Wednesday and continues to deepen as it heads towards northern Quebec, expect the winds to slowly continue backing to the northwest with time, with wave heights increasing to 14 to 19 feet over the north central and eastern lake behind the low. As cold air advection continues to cycle in from the northwest Wednesday night through Thanksgiving, we could see some light freezing spray develop across the lake as gales of 35 to 45 knots slowly weaken with time from west to east, eventually ending late Thursday night. As weak high pressure ridging moves overhead late this week into this weekend, expect the winds to die down to 20 knots or less again.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Storm Watch from Tuesday evening through Thursday morning for MIZ001>004-009-084.

Lake Superior... Gale Watch from Tuesday evening through Thursday morning for LSZ162-240>242-263.

Gale Watch from Tuesday evening through Thursday evening for LSZ243-244-264.

Gale Watch from late Tuesday night through Thursday evening for LSZ245>248-265.

Gale Watch from Wednesday morning through late Thursday night for LSZ249-250.

Gale Watch from Wednesday afternoon through late Thursday night for LSZ251-267.

Gale Watch from late Tuesday night through late Thursday night for LSZ266.

Lake Michigan... Gale Watch from Wednesday afternoon through Thursday afternoon for LMZ221-248-250.