textproduct: Grand Rapids

KEY MESSAGES

- Lake Effect Snow Continues Early this morning

- Widespread Accumulating System Snow Expected Saturday into Sunday

DISCUSSION

Issued at 356 AM EST Fri Nov 28 2025

- Lake Effect Snow Continues Early this morning

The ongoing lake effect continues to dwindle. However bands of heavier snow and reduced visibilities persist based on webcams, observations and latest radar. Have trimmed the area back through the north and counties west of US 131. Will continue the advisory for Muskegon county southward along the lakeshore. Latest bufkit soundings show the DGZ contracts after 7 AM. So while the northwesterly flow continue through mid morning, any snow bands will become light. So early morning commute along the lakeshore could still be affected.

- Widespread Accumulating System Snow Expected Saturday into Sunday

Will continue to hang on the winter storm watch this morning. There remains some question on timing and intensity. The snow should move in through the course of Saturday morning reaching peak intensity Saturday afternoon and especially Saturday evening.

The Surface to mid level low still expected to form through Eastern colorado as the upper level wave descends the mountains. It's interesting to note that the 850mb level through central and Western Colorado is literally in the dirt. Terrain rules then show as the low treks eastward it will pass through the great plains and make a northeasterly turn across southern lower Michigan.

The surface east to southeasterly flow on Saturday will bring warm air advection snow out ahead of the low. Warm air advection is a relative term. 850mb temps over the area should be in the -10 to -15C range. The system will have about -7C at 850mb air attached to it. That shift should create an isentropic upglide that will form moisture aloft a create a long and deep Dendritic growth zone. There remains some questions on snow to liquid ratios (SLR's). Expect some shifting of the SLR's as the system moves through. The first portion will be closer to normal, around 13 to 1. From mid to late Saturday evening, ratios could switch to around 15 to 16 to 1. That would allow for larger flakes and larger accumulations. Still thinking 6+ inches will occur over much of the forecast area, with the the exception being the U.S. 10 corridor which may come in just below those totals. Right now the heaviest swath looks to occur from our southwest CWA near Holland and South Haven through Grand Rapids and Lansing towards Alma. In the southwest areas near and south and west of GRR totals may exceed 8 inches. We still have time to nail down amounts so as stated before, will hang onto the watch for now.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 620 AM EST Fri Nov 28 2025

Intermittent lake effect bands continue this morning. The bands will continue to weaken as the morning continues. Periods of MVFR cigs and vsbys remain possible through 18Z. Drier air will filter in which will allow VFR conditions to dominate the rest of today and tonight.

MARINE

Issued at 337 AM EST Fri Nov 28 2025

Winds and waves continue to diminish this morning and any isolated gales will fade and conditions dangerous to small craft will persist today.

Previous Discussion: To wrap up this past event...the Southern Lake Michigan Buoy peaked at 13.5 feet (significant wave height). Significant wave height correlates to the highest 1/3 of waves rolling through the buoy. So higher waves existed within the spectrum of what was occurring out there. In westerly flow we likely had higher waves in our nearshore waters given 40 more miles of fetch downwind of the buoy. With our nearshore buoys out for the season we do not know exactly what the waves peaked at but in the 14-20 foot range is likely.

In terms of wind, the highest gusts were 63 mph at Big Sable Point and the Grand Haven Light, 62 mph at the Saugatuck Pier, 61 mph at the St. Joe Pier and 60 at the Muskegon Pier.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Winter Storm Watch from Saturday morning through Sunday morning for MIZ043>046-050>052-056>059-064>067-071>074. Winter Weather Advisory until 7 AM EST this morning for MIZ050- 056-064-071-072. MARINE...Small Craft Advisory until 9 PM EST this evening for LMZ844>849.