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KEY MESSAGES

- Localized Lake effect snow showers near northern Lake Michigan and Whitefish Bay coastal areas tonight thru early Friday morning

- Widespread light to moderate (locally heavy) snow moves in from the west Friday night, transitioning NW lake effect snow early Saturday. Cold temperatures linger this weekend

- Robust lake effect snow is possible late Saturday into Sunday for typical snowbelt locations

- Temperatures could warm to above freezing mid week next week

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 153 PM EST Thu Dec 11 2025

Current satellite is depicting a large scale PNA pattern over North America today, hinting at the pattern change to come. Under the upper closed low exiting, some lake effect snow showers are continuing over parts of NW lower (near and southeast of Grand Traverse Bay are the most robust showers). North winds are ushering in drier air and will continue to shift the focus of heaviest lake effect to the west. At the same time, the strength of the bands will continue to weaken over the early afternoon hours today. Initial reports of 1 to 4 inches has been seen, with local reports up to 7" (areas where the heavier bands have trained last night and this morning).

Tonight: Although the surface airmass will be on the move, the colder and drier condtions will be over northern MI tonight, which leads to most of northeast lower dipping down to single digits (wouldn't be surprised to see a few sites less than 0F). Some cloud cover will likely linger over northwest lower, however surface temperatures should still dip into the teens with this cooler airmass. Winds will become light near the surface, with light LL NW/W flow (~850mb). This environment has the potential to result in some mesoscale snow showers along the coast of northern Lk MI and near Whitefish Bay. A land breeze will likely form over the warmer lake waters for Lk MI, and drainage flow should establish an area of LL convergence over Whitefish bay.

Uncertainties: At this time, it is difficult to pin down exactly where a heavier LES shower or two will be over northern Lk MI, as small scale interactions will be driving the convective initiation. Totals could amount to a few (1-4) inches in localized areas. There is slightly better confidence in snow showers forming over Whitefish Bay and moving towards the SOO late tonight into Friday morning due to the Canadian shield being cloud free tonight. Two things are preventing an advisory issuance this afternoon; the first is the extreme variability in the location of heaviest accumulations. These showers will likely be transient in a weak synoptic forcing regime and under light LL winds. This yields a higher likelihood in the snow amounts spreading over a larger area (keeping near the coastal areas/adjacent areas tho). The second is the environment; many of the CAM soundings show profiles with a near surface inversion, dry air at the top of the DGZ (leading to shallow DGZ depths), and the omega maximized just below the DGZ. These profiles result in lower SLRs, and even the possibility of brief freezing drizzle instead of snow for some spots (not the best snow production soundings).

Friday: Winds will turn southwest early Friday morning, moving in any snow showers that stayed over the waters inland. This results in light snow & clouds tomorrow morning for coastal NW lower. Winds won't strengthen until later Friday as surface gradients increase. As southwest winds strengthen, lake effect/enhanced snow will be seen over parts of Mackinac, Chippewa, and Emmet counties. Winds shift overnight to west, then northwest. This will push moderate to heavy snow showers inland over northern lower for Friday night. Initial thoughts for snow accumulations late Friday and Friday night are generally 2 to 4 inches with locally higher amounts up to 6 inches. This could change as more CAMs come in.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 153 PM EST Thu Dec 11 2025

A closed low slides down the northwesterly jet over the central plains, towards MI early Saturday. This will introduce some synoptic help and colder LL temperatures to aid in continuing NW lake effect snow showers through much of the weekend. More robust snow showers will be seen over eastern upper Saturday due to some lake aggregate troughing in response to a very cold LL airmass moving in. A burst of intensity will be seen over much of the forecast area late Saturday into Sunday as the upper low swings through.

Cold temperatures will be around this weekend due to the colder airmass in place. Overnight temperatures will drop where skies can clear (typical cold spots of NE lower).

Next Week: Although upper ridging will likely not reach northern MI next week, zonal flow and southerly LL/surface winds will. Temperatures will warm to near freezing, reaching freezing and/or above by mid week. Some hints at precipitation chances indicate that mixed precip and/or rain could be seen, however it is too early to nail that down for sure.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1129 AM EST Thu Dec 11 2025

Bouncing between VFR and MVFR courtesy of passing snow showers through the afternoon. Anticipating MVFR generally during snow showers and marginal MVFR to IFR outside snow showers. Potential for lower CIGs and VSBYs in any snow showers. Much of this activity should taper this afternoon... with just NW lower sites and CIU clinging to snow shower chances tonight into tomorrow.

APX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory until 4 PM EST this afternoon for MIZ021-026-027-033-034. MARINE...Small Craft Advisory until 4 PM EST this afternoon for LMZ323- 341-342-344>346.