265
FXUS63 KGRR 281744
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1244 PM EST Fri Nov 28 2025

.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 /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1244 PM EST Fri Nov 28 2025

Key changes:
- removed short term vsby restrictions per earlier expectations
- added MVFR vsbys/cigs most terminals chiefly after 12Z Saturday

Forecast expectations have not changed substantially since the
12Z package this morning. Radar indicates lake effect snow
continuing to subside with one dominant band perhaps affecting BTL
with brief MVFR visibility restrictions prior to 20Z.

Confidence for VFR conditions areawide are reasonably high after
20Z today and lasting into the 02-04Z timeframe. Gusty winds will
become light and variable starting around 00Z and lasting much of
the overnight hours as a north-south oriented surface pressure
ridge moves east across Lower MI. We will then see a gradual west
to east deterioration in conditions during the day Saturday.


&&

.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.
MARINE...Small Craft Advisory until 9 PM EST this evening for LMZ844>849.

&&

$$

DISCUSSION...Ceru
AVIATION...TJT
MARINE...Duke