textproduct: Marquette

KEY MESSAGES

- Moderate to heavy lake effect snowfall and areas of blowing snow continue over the northwest wind snowbelts tonight into Sunday. See the latest Winter Weather Message for additional information.

- Northwest gales and heavy freezing spray are expected on Lake Superior into early Sunday.

- Below normal temperatures continue this weekend before a warm up above freezing next week.

DISCUSSION

Issued at 422 PM EST Sat Dec 13 2025

Afternoon GOES water vapor imagery and RAP analysis have the closed low centered just northeast of Lake Superior with the weakening surface low to the northeast over Quebec. With cold 850mb temps of - 23C to -27C descending across the region and Lake Superior surface temps holding around 4C, delta-Ts will be more than sufficient for moderate to heavy LES showers. Inversion heights initially between 5- 7 kft (higher in the east) are also supportive, but the best moisture is above the DGZ which is located near or at the surface. This alongside stronger winds gusting up to 35 mph near Lake Superior is not ideal for snow growth processes, and because of its resulting fine grain-like structure, will be more prone to drifting and blowing. As the closed low settles southeast into Sunday, winds shift more northerly and shower coverage increases. Up to an additional 4 inches of snow is possible in the western spine of the UP with highest amounts expected south of Houghton and in the higher terrain. 3-8 inches is expected over the east with localized amounts approaching a foot in Alger and northern Schoolcraft, particularly east of Munising (around and north of M-94). North central areas are expected to see an additional 0.5 to 3 inches of snow. Mostly maintained Winter Weather Advisories as is, however extended Alger and northern Schoolcraft through 10 AM EST for lingering moderate to heavy snowfall during the morning hours.

Otherwise temps bottom out this evening, mostly in the single digits above and below 0 with some low teens near eastern Lake Superior. Wind chills will flirt with -25F interior west early on, but widespread Cold Weather Advisory criteria is not expected. Temps and windchills will improve overnight as high pressure builds in and warm air advection begins aloft. This high pressure continues to dry out the profile, weaken delta-Ts with WAA, and lower inversion heights, diminishing LES on Sunday. Winds shift southeast through the day, lifting any lingering LES out over the lake. Up to an additional 3 inches of snow is expected over the east by Sunday evening. Highs on Sunday will be in the teens to mid 20s, warmest east.

After this weekend, expect a pattern shift from below to above normal temps. A shortwave and weak clipper system looks to move north of the Great Lakes on Monday, supported by the left exit region of a 115 kt jet. While lift is present, thermodynamic profiles are unimpressive. Trailing light LES is also briefly anticipated on the backside of this system. Up to 3 inches of snow is likely with this round, highest amounts in the northeast with parts of the interior west and south central likely staying dry (75% chance).

Once the rex block over the Pacific breaks down, widespread temps return above freezing for the first time in weeks. With winds out of the southwest ahead of the next clipper system, some downslope areas may push into the 40s on Tuesday. While the cold front of the Clipper could bring light lake effect back over northwest wind snow belts Tuesday night, not much, if any measurable snowfall, is expected. Model soundings do indicate a low chance (25%) for drizzle or freezing drizzle mixing in late Tuesday afternoon into Tuesday night over the east.

A strong clipper system is projected to track across the Upper Great Lakes late next week. Will continue to monitor for potential winter impacts, however gusty winds up to 30-40 mph are possible (30-50% chance). In the wake of this system, near normal temps are forecast.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 632 PM EST Sat Dec 13 2025

Lake effect snow showers and gusty WNW winds will continue to produce IFR to LIFR conditions at KIWD and KCMX through this evening. Showers will be a little more sporadic at KSAW, with prevailing VFR eventually trending down to MVFR 03-06z as showers move in and out of the terminal. Expect a gradual improving trend across the west overnight as snow begins to diminish in intensity 03- 09z Sun, with predominant IFR conditions trending towards MVFR 12- 18z and eventually to VFR near the end of the TAF period.

MARINE

Issued at 422 PM EST Sat Dec 13 2025

Anomalously cold Arctic air descending over Lake Superior into this evening will allow strong northwesterly winds 20-30 kts to mix down to the lake surface. Gale force gusts up to 40 kts are expected over the east this evening into tonight, keeping moderate to heavy freezing spray going across the open waters. As the winds veer more northerly tonight, expect an increase in the winds slightly over the north central and eastern lake this evening before ridging moving in on Sunday calms things down and brings an end to the freezing spray by Sunday afternoon. Winds are expected to settle to 20 kts or less by late Sunday afternoon, although with a Clipper looking to move just north of the lake late Sunday night into Monday, chances for southwesterly gales increase to around 30-50% (highest over the west). Opted to hold off on a Gale Watch as timing is brief and exact placement is not as certain. Expect winds to weaken, falling back below 20 kts by Monday night in the wake of the low as a weak ridge briefly extends overhead. Ahead of and immediately behind the low, some moderate freezing spray is expected.

As a deepening Clipper low traverses through Canadian Prairies and northern Ontario Tuesday, expect the winds to pick up from the southwest with time, with gales up to 40 kts possible by Tuesday afternoon (30-60% chance). After another ridge slackens the winds across the lake to 20 kts or less by Wednesday afternoon, an anomalously vigorous and deepening Clipper low moving across the Upper Great Lakes looks to potentially bring high-end gales across the lake on Thursday (20-40% chance of 45+ kt). This likely would bring another round of moderate to heavy freezing spray across the lake.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 1 AM EST /midnight CST/ Sunday for MIZ001>003-009.

Winter Weather Advisory until 10 AM EST Sunday for MIZ006-085.

Winter Weather Advisory until 7 AM EST Sunday for MIZ007.

Lake Superior... Heavy Freezing Spray Warning until 1 AM EST /midnight CST/ Sunday for LSZ162.

Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Sunday for LSZ240>245-248>251-263>267.

Gale Warning until 7 AM EST Sunday for LSZ244>246-248>251- 264>267.

Lake Michigan... None.