176
FXUS63 KGRR 252320
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
620 PM EST Tue Nov 25 2025

.KEY MESSAGES...

- Lake Effect Snow Event Wednesday through Thursday Night

- Strong Winds Expected

- Another Snow Event Over the Weekend

&&

.DISCUSSION...
Issued at 336 PM EST Tue Nov 25 2025

- Lake Effect Snow Event Wednesday through Thursday Night

All eyes with this forecast are on the lake effect snow event that
begins Wednesday morning and persists into Friday morning. The
worst conditions will occur Wednesday afternoon and Wednesday
night. We are looking for two distinct areas of higher snowfall,
namely our northwest forecast area up along and near U.S. 10 and
in the southwest (south of GRR down to I-94). We are looking at
3-8 or 4-8 inch totals in our northwest 6 counties (Mason, Lake,
Osceola, Oceana, Newaygo and Mecosta). Totals in the southwest
will be more in the 3-6 or 3-7 inch range. Totals in between these
two areas including Muskegon, Ottawa and Kent Counties will be
more in the 2-4 or 2-5 inch range. Bottom line we have Winter
Storm Warnings in the northwest and southwest corners of the CWA
and a Winter Weather Advisory in most other areas. The counties
that do not have a winter headline include Gratiot, Clinton and
Ingham Counties.

As for the details, all necessary ingredients are in place but
some are not as off the charts as others. For the ingredients that
are in place that will help conditions...we will have plenty of
instability to work with as delta T`s will be near 20 increasing
into the lower 20s C with time. Synoptic scale lift will be
present as well as a strong shortwave plows into the region
tonight will upper cyclonic flow persisting through Thursday
night. Upper cyclonic flow (which supports synoptic scale vertical
motion) peels away to the east Thursday night. It is the synoptic
scale lift that boosts most lake effect events into the high
category of amounts and impacts. Moisture is in place, but it is
not overly impressive in the 850-700mb layer which takes lake
effect events into another category. So, this event has plenty
going for it, but the depth of moisture could be a bit better
especially Thursday into Thursday night.

- Strong Winds Expected Which Lead to Impacts

Strong winds with this system push marginal snow amounts into the
warning category in the areas where we issued for. Winds will gust
Wednesday into Wednesday night into the 45 to 60 mph range across
the entire area. We have issued a High Wind Warning for the
lakeshore counties and a Wind Advisory inland. Gusts of around 60
mph can be expected towards the shore and 55 mph inland in spots.
These winds combined with falling snow and falling temperatures
will make for travel impacts in one of the busiest travel times of
the year. People traveling Wednesday afternoon into Wednesday
night across Western Lower Michigan need to know that travel
conditions will be poor given the strong winds and falling snow
which will limit visibility. Air temperatures fall below freezing
Wednesday night which will make slippery conditions increase.
Thankfully salt will be able to mitigate this event as we will be
above 25F for the most part into Thanksgiving evening.
Thanksgiving night however we fall into the lower 20s in many
areas. Power outages are certainly possible given the magnitude of
the wind, but thankfully most leaves are off the trees now which
will limit surface area and drag.

Again, we are concerned about the period of heaviest snow that
happens to line up with the strongest winds. Wednesday afternoon
and evening will likely see occasional whiteout conditions in the
heaviest snow bands. Given we have not had much winter weather yet
this year, this event will be have a bit more impact as folks
remember winter driving skills.

- Another Snow Event Over the Weekend

Surface low pressure develops in the lee of the Rockies in
Colorado Friday night and tracks through the Great Lakes from
Saturday into Sunday. At this point it looks like another 3-6
inches of snow is possible. Both the operational GFS and ECMWF are
showing amounts to this magnitude. Given the cold air in place the
precipitation looks to be all snow. More on this system after we
work through some of the first. Suffice it to say, winter is here
and it looks to stay for awhile.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 620 PM EST Tue Nov 25 2025

Prevailing IFR/LIFR with low ceilings and drizzle/mist early
tonight, some temporary breaks into MVFR possible. Cold front with
rain showers sweeps through from west to east between 06 and 12
Z. May be a brief break into MVFR behind the cold front for part
of Wed morning, but rain/snow mix changing to snow during the day
Wed will then carry likely IFR for much of the area. Increasingly
strong wind gusts from the southwest Wed morning become more from
the W then WNW later in the day.

&&

.MARINE...
Issued at 336 PM EST Tue Nov 25 2025

We have upgraded the Storm Watch to a Storm Warning from Wednesday
into Wednesday night. We have maintained the Gale Warning on the
front side of the Storm Warning late tonight.

Deep low pressure (around 992mb) will move through the Northern
Great Lakes tonight into Wednesday night which will push a cold
front through Lake Michigan tonight. Surface high pressure in the
plains to around 1030mb will create a 50mb pressure difference
across our region which is a significant pressure gradient. Winds
will ramp up behind the front quickly moving from gales to storm
force in a short amount of time Wednesday morning. The worst of the
conditions will occur Wednesday afternoon and evening when 50-55
knots are forecast in the mixed layer up and down our shoreline.
Given cold air advection and winds of this magnitude waves will
build rapidly and reach levels that are fairly rare. Waves of 14-20
feet are likely up and down the shoreline. Waves in excess of 20
feet are possible, especially south of Muskegon.

To keep things simple we got rid of the Gale Warning on the back end
of the Storm Warning. A Gale Warning will be needed on Thursday, but
we can downgrade into that once the more high priority storm ends.

We are not concerned about lakeshore flooding at this point given
water levels are 4+ feet below our advisory criteria. We do not get
into trouble until around 582.5 feet on Lake Michigan and this
afternoon we are hovering around 578 feet. We will likely rise a
couple of feet given the magnitude of the wind, but 4+ feet will be
difficult. We will be monitoring.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...High Wind Warning from 7 AM Wednesday to 7 AM EST Thursday for
     MIZ037-043-050-056-064-071.
     Winter Storm Warning from 7 AM Wednesday to 7 PM EST Thursday
     for MIZ037>039-043>045-064-065-071>073.
     Wind Advisory from 7 AM Wednesday to 7 AM EST Thursday for
     MIZ038>040-044>046-051-052-057>059-065>067-072>074.
     Winter Weather Advisory from 7 AM Wednesday to 7 PM EST Thursday
     for MIZ040-046-050-051-056>058-066-074.
MARINE...Gale Warning from 1 AM to 7 AM EST Wednesday for LMZ844>849.
     Storm Warning from 7 AM Wednesday to 1 AM EST Thursday for
     LMZ844>849.

&&

$$

DISCUSSION...Duke
AVIATION...CAS
MARINE...Duke