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KEY MESSAGES

-Light lake effect activity along the coasts this morning into the early afternoon.

-Larger system brings widespread snow accumulations across all of northern lower and eastern upper Michigan later today through Sunday morning. Quick bout of lake effect snow on the backside of the system Sunday night through Monday.

-Additional snow chances return around midweek, with more lake effect snow chances beyond that.

SHORT TERM /THROUGH SUNDAY/

Issued at 331 AM EST Sat Nov 29 2025

Pattern Synopsis:

Bit of a transition period underway across the Great Lakes... with potent closed low delivering an impressive (and to a lesser extent, still ongoing) lake effect snow outburst is moving into Atlantic Canada, while a brief period of ridging builds into the region, courtesy of an oblong area of surface high pressure stretching from roughly Manitoba to the Tennessee Valley. Next item of business is quick to build into the region... as a pretty stellar northern stream shortwave digs from the northern Rockies into the Corn Belt region by daybreak. Lee cyclogenesis well underway at the surface, with surface low pressure currently festering over western Kansas set to draw in moisture from the Gulf, overlapping with an already chilly airmass in place over much of the northern CONUS. Result will be the eventual return of accumulating snowfall to the region as this surface low lifts from the mid Mississippi Valley into Michigan tonight into Sunday.

Forecast Details:

Weakening flow due to surface high pressure moving into the region is beginning to spell the demise from the ongoing lake effect snow regime... anticipating this activity to confine itself closer to the coast through the morning as land-lake breeze interactions continue to support some convection. Some additional light snow accumulations will be possible into early this afternoon along the immediate shorelines. As the aforementioned system builds into the region and antecedent south to southeasterly flow builds into the region, this activity will be forced north and west, with potential for snow showers to manifest across parts of Mackinac County, southeast Chippewa county, and the Whitefish Bay region. Accumulations again look to be rather light.

Now to the bigger story during the forecast period...

Strong isentropic lift ahead of the system will lead to most of the region being basically overcast by the afternoon despite the best efforts of surface high pressure. A combination of drier air through the profile from the surface high and a slowing system as it approaches Michigan (due to the heavy occlusion of the surface low with time) will lead to snowfall onset largely waiting until the late afternoon hours, but still anticipating the snowfall to commence from SW to NE late this afternoon into early tonight. Surface low pressure track will be from SW lower into the Saginaw Bay region and northern Lake Huron by Sunday afternoon. As such, system will be considerably vertically stacked with a slackening thermal gradient due to the occlusion. Those impressive snowfall amounts that look to materialize across Wisconsin, Illinois, and SW lower Michigan may struggle to do much more than leak into Saginaw Bay as the overall lift with the system weakens with time. Nonetheless... ample saturation and sufficient lift through the DGZ will lead to a widespread accumulating snowfall (and wetter snow too... ratios generally 9 - 12 to 1) across the region tonight before tapering into Sunday morning.

As far as where the heaviest snowfall is anticipated, there are three distinct areas to highlight. All snowfall ranges will be from an 18z / 2pm Saturday to 18z / 2pm Sunday range (24 hours).

The general expectation is that the swath of heaviest snow solely form the system will generally favor the Saginaw Bay region, given proximity to the system. Winter Storm Warnings have been hoisted for Gladwin, Arenac, Ogemaw, Iosco, and Alcona counties for potential to see up to 8 inches of snow by the time snowfall tapers Sunday. There are a couple mesoscale / lake elements to consider as well.

Strong SSE flow off the lakes will contribute to some enhancement across far northeast lower... specifically the region between Alpena and Rogers City (think US 23 along the lakeshore)... where a separate Winter Storm Warning has been hoisted for potential to see localized snowfall in excess of 8 inches. There is a bit of uncertainty with guidance among this feature, but more and more guidance is buying into the idea of this zone of lake enhancement actually moving ashore (some of the most aggressive models try to slam 15" of snow into this area, so there's your ceiling).

A third and final area to highlight is the eastern Mackinac / southeast Chippewa region, where that SSE flow will lead to another area of lake enhancement. Winter Storm Warnings have been hoisted for these two zones as well for potential to see localized accumulations in excess of 8", and much like northeast lower, with the most aggressive guidances putting a ceiling of 15" by Sunday afternoon.

All other areas will remain in Winter Weather Advisories for this forecast cycle due to widespread hazardous travel from reduced visibilities and snow covered / slippery roads. West of I-75 in eastern upper generally is set to see 3 to 5 inches of snow from this event. The rest of northern lower probably lands in the 4 to 6 inch range (perhaps 3 to 5 inches across the Grand Traverse Bay region, locally up to 7 inches across the higher terrain of interior northern lower).

In the wake of this system, gusty winds and lake effect snow builds into the region later Sunday afternoon and into Sunday night. For more details on this, see the discussion below (long term).

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 331 AM EST Sat Nov 29 2025

One thing that I will start this discussion off with is that this particular round of lake effect snow (Sunday - Monday) doesn't quite have the pazazz the Thanksgiving event showcased. Nonetheless, anticipating potential for additional accumulations on top of that system snow to materialize. Strong NNW flow cold advection leads to a window of snow showers reaching well inland for a brief period (perhaps on the order of 6 to 10 hours)... but a quick return of surface high pressure to the south will shift an initial NNW flow regime with strong winds to a lighter SW flow regime. As such, anticipating the focus of snows to shift around a bit through Monday, and thus limiting any single area from getting clobbered like the most recent event. Nonetheless, continuation of snow induced travel hazards anticipated across northwest lower and portions of eastern upper later Sunday into Sunday night... shifting to the Straits for Monday and into Tuesday. The more concerning of these two lake effect regimes will definitely be later Sunday into Sunday night as better moisture and strong winds will lead to intermittent periods of heavy snowfall rates overlapping gusty winds bringing blowing / drifting snow concerns.

The active pattern marches on as another northern stream system races through around midweek and delivers another brief shot of somewhat more widespread snow to the region. This appears to be a bit of a quick mover and looks moisture starved, so not anticipating heavy snowfall accumulations at this juncture. Additional lake effect snow chances continue in the wake of the midweek system as we remain near to below normal in the temperature department. So with all that, surely looks like an excellent start to the winter recreation season is underway as this pattern looks to continue its dominance into mid December, per longer term guidance.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1047 PM EST Fri Nov 28 2025

Lake effect clouds and some snow showers continue. Brief MVFR/IFR conditions possible at CIU overnight, and maybe just maybe PLN. Otherwise VFR to perhaps MVFR cigs overnight and Saturday morning. In the afternoon/evening, widespread snow returns to the area from the sw, with IFR cigs/vsbys.

Light nw winds this evening, becoming light se-erly Saturday.

APX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory from 7 PM this evening to 1 PM EST Sunday for MIZ016-017-022-023-029-086-087-095-097>099. Winter Storm Warning from 7 PM this evening to 1 PM EST Sunday for MIZ018-024-088-096. Winter Weather Advisory from 4 PM this afternoon to 1 PM EST Sunday for MIZ020-021-025>028-031>034. Winter Storm Warning from 4 PM this afternoon to 1 PM EST Sunday for MIZ030-035-036-041-042. MARINE...Gale Watch from Sunday afternoon through Sunday evening for LHZ345>349. Gale Watch from Sunday morning through Sunday evening for LMZ323-341-342-344>346. Small Craft Advisory from 4 PM this afternoon to 4 AM EST Monday for LSZ321-322.