textproduct: Marquette

KEY MESSAGES

- Winter Weather Advisory remains in effect until the early afternoon for an additional 2-4 inches of snowfall in the eastern UP, associated with NW wind lake effect snow bands.

- Gale Warnings are in effect for much of Lake Superior for northwest winds up to 40 knots this morning and southwest gusts up to 40 knots tonight. Both rounds will be accompanied by moderate to heavy freezing spray and waves of 8+ ft.

- Colder than normal temperatures continue through the forecast. Expect wind chills below zero across much of the U.P. tonight.

DISCUSSION

Issued at 447 AM EST Thu Dec 4 2025

Early morning KMQT radar returns show light lake effect snow showers for Marquette County and west with several stronger NW-wind LES bands over Alger, Schoolcraft, and Luce Counties. Observations show that the temperatures across much of the interior UP have fallen to the single digits, with the current lowest temperature being reported in the Watson region of southern Marquette County at negative 3. Aloft, few longwave features are noted at 500mb over North America, with the dominant feature being a Hudson Bay closed low with a few shortwaves embedded within the peripheral flow. Elsewhere, a Rex Block is set up off the Pacific Coast, with the closed low being off the coast of Los Angeles and the Baja California, while the ridging is off the Pacific Northwest and British Columbia coast. As this blocking pattern is in no hurry to progress (especially as the number of longwave features downstream is low), the weather pattern over Upper Michigan will be dictated by the aforementioned embedded shortwaves within the flow around the Hudson Low and any shortwaves embedded in the northwesterly flow proceeding through the Canadian Rockies. Either shortwave mechanism is primed to deliver clipper-type low pressure systems, though given the diminutive size of the parent troughing features, these clippers will not be particularly strong. However, the cyclonic surface flow and shot of cool air over the warm Great Lakes that come with each clipper will mean that the more impactful weather this forecast period will be the post-system LES.

For today, CAMs show little change in the structure and location of LES bands until around 18Z today. As 850mb temps remain in the negative 20s C over a Lake Superior still around 5 C, thermodynamic support for the bands will remain healthy. Throughout today, as a surface high skirts to the south of the Great Lakes, ridging will bring dry air, falling inversion heights, and eventually will back the winds to be offshore this afternoon. Thus, while the Winter Weather Advisory has been extended to 18Z in the east (2-4 additional inches of accumulation expected), LES will definitely cease for at least some period this afternoon and evening in the east. As the winds shift out of the west to southwest, some LES will linger over the Keweenaw Peninsula, but accumulations should be 1" or less. Besides the precipitation, gusty NW winds will continue this morning in the east especially along Lake Superior as cold advection behind the low helping wind gusts of 35+ mph mix down to the surface. In conjunction with the falling snow, the wind will cause some lower visibility at times and snowdrifts over some roads, which could make travel difficult in some spots for the morning commute. While the winds will relax some as ridging moves over the UP this evening, not much temperature relief is expected with the typically warm southwest winds, as highs today are only forecast to be in the teens, and perhaps cooler in the interior west.

The next pair of floats in this parade of clipper lows/fronts comes tonight and Friday evening, both with surface lows around 1004 mb. Neither feature looks particularly impactful in terms of synoptic precipitation, though the lake effect snow portion may be more impactful. NAM soundings for Munising show a warm nose (note: not above freezing, so no precip type issues) that keeps much of the saturated profile warmer than the DGZ, so snow ratios might not be as high as what's been observed with the ongoing LES. Additionally, moisture itself might be a challenge as even the moist-biased NAM struggles to saturate much of the near-lake surface layers, likely due to the aforementioned ridging drying things out as well as the nature of NW flow being more continental (and thus, dry) compared to a more summery pattern or a CO Low pattern where there is a Gulf connection to provide moisture transport. All this to say, snow accumulations may be an inch here, a couple inches there, but chances of 4+ inches of snow in any given day are 20% or less within this pattern.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1215 AM EST Thu Dec 4 2025

Lake effect snow continues tonight, resulting in ceilings and reduced visibilities. Main impacts are expected at KCMX, which is likely to remain IFR or LIFR overnight due to showers and winds gusting near 30kts. Improvement to MVFR is expected Thursday morning. Winds shift to westerly and then southwesterly, which may help to refocus shower activity into KCMX by afternoon.

KIWD and KSAW could see MVFR conditions tonight, but confidence isn't as high, so prob30 groups were included. Conditions improve by morning to VFR at KIWD/KSAW as winds settle. Another wave of snow and gusty winds moves into Upper Michigan late Thursday, which may result in low level wind shear at KIWD and conditions trending toward MVFR after 0z.

MARINE

Issued at 447 AM EST Thu Dec 4 2025

Northwest gales fall below 35 kt in the east this morning, however, southwest winds ahead of the next Clipper Low will ramp up in the west this evening to gales of 35 kt, spreading across the rest of the lake up to 40 kt tonight. While heavy freezing spray is an ongoing threat with the first gale this morning, freezing spray rates will be more moderate with the gale this evening into Friday. Waves in the east will quickly fall from 12-15 ft to below 8 ft by this afternoon. In the west, waves quickly ramp up to 9-13 ft tonight. Friday, wind gusts fall to near 20 kt and waves fall to near 4 ft. Saturday morning, post-frontal northwest winds will ramp up to 30 kt, with chances of a brief 35 kt gale around 40 percent. The weather pattern into next week looks to continue with periodic Clipper Lows that will bring either increased southwest winds ahead of it and/or gusty northwest winds in its wake.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 1 PM EST this afternoon for MIZ006-007-085.

Lake Superior... Gale Warning from 4 PM EST /3 PM CST/ this afternoon to 4 AM EST /3 AM CST/ Friday for LSZ162-240>242-263.

Gale Warning until 7 AM EST this morning for LSZ243>248-264- 265.

Gale Warning from 7 PM this evening to 7 AM EST Friday for LSZ243>251-264>267.

Heavy Freezing Spray Warning until 7 AM EST this morning for LSZ244-263-264-266.

Gale Warning until 10 AM EST this morning for LSZ249>251-266- 267.

Lake Michigan... Gale Warning from 10 PM this evening to 7 AM EST Friday for LMZ221-248-250.