970
FXUS63 KGRR 071129
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
629 AM EST Sun Dec 7 2025

.KEY MESSAGES...

- Light snow event tapers off today

- Light snow Mon night/Early Tue; Mixed Precipitation Wed

- Another system Friday with reinforcement of colder air next weekend

&&

.DISCUSSION...
Issued at 327 AM EST Sun Dec 7 2025

- Light snow event tapers off today

The next part of the ongoing clipper train is arriving here this
morning on time with light snow spreading across the area. This
light snow is out ahead of the next short wave of the series
currently over MN. In addition, we have coupled jet forcing from a
departing jet streak over the UP and Eastern Ontario, and the upper
jet streak coming in on the backside of the wave over MN. The
forcing from the jet coupling will be tapering off this morning.
This will help to diminish the snow intensity and amounts compared
to areas to our WSW where the advisories and warnings are in place.

We are looking at higher end amounts being 2-3 inches across the
southern half of the forecast area, with less further north and
inland. The snow will come to a fairly quick end this morning as the
MN wave moves through by 18z this afternoon. A few light lake effect
snow showers may linger over the NW corner of the area this
afternoon as nrly flow will bring some snow showers to Big and
Little Sable Points, and downwind from Grand Traverse Bay. These
will be transient, with little additional accumulations.

- Light snow Mon night/Early Tue; Mixed Precipitation Wed

We will see a little longer relative break in between systems from
this afternoon through Monday compared to the last couple of short
breaks. We do see a short wave that comes through Monday afternoon,
but the bulk of this forcing goes south of the area, and broader
scale upper ridging results in sfc ridging remaining in place, and
will limit precipitation during the day.

Not far behind the Monday afternoon short wave will be another short
wave that is currently offshore of British Columbia that will
approach the area Monday night. This one will be a more direct hit
than the Mon wave. Even though it is a direct hit, it will once
again be moisture starved. Much of the area will see an inch or two
of snow accumulation. The best snow will fall once again across the
NW corner of the forecast area toward Ludington. This is due to
enhancement of moisture and instability coming in off of Lake
Michigan with the flow from the SW with the sfc low over Lake
Superior. An advisory for the NW corner of the area is not out of
the question for Mon night/Tue morning.

We see a break in the snow Tuesday afternoon, with additional
precipitation developing quickly Tuesday evening. This wave has been
well advertised to be a bit stronger by all of the model data over
the past few days. This is the result of the upper flow buckling a
bit, and the jet streak being a bit stronger, around 145 knots
feeding this wave.

What is interesting, and a bit counter-intuitive, is the low will be
a bit further south that the Monday night system. However, the
strength of the low will draw warmer air ahead of it, and change
some of the snow to rain south of the low track late Tuesday night
into early Wednesday afternoon, before it goes back to snow as
colder air comes in later Wednesday behind the system.

Just north of the sfc low, a band of better snow is expected to
fall, on the order of likely a general 3-5 inches or so. The track
of the low has been fluctuating a little bit by 20-40 miles, which
makes a big difference in this case. We expect this to continue,
but  the trend over the last 24 hours for it to go a little further
north across Central Lower.

A break bout of lake effect will be possible behind the Wed system
as the flow aloft will remain cyclonic for a bit along with a shot
of colder temperatures. This looks like right now to be more of a
flow from the NNW, favoring mainly the lakeshore counties.

- Another system Friday with reinforcement of colder air next weekend

The train of short waves only continues late in the week too, as yet
another more potent short wave takes aim on the area on Friday. It
will be another system with limited deep moisture with no good
moisture source being tapped, but the lakes helping things out a
bit. Then, another reinforcing shot of colder air comes in with 850
mb temperatures dropping to the negative mid teens C. This will get
the lake effect machine going again then going into next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 628 AM EST Sun Dec 7 2025

Light snow is ongoing at all of the terminals as of press time for
the 12z forecasts. We are likely at the peak of the event as of
1130z, with snow expected to steadily taper off and conditions to
gradually improve after 13z or so from NW to SE. Low clouds around
2500 ft are likely to hold on for a few hours, along with a few
light snow showers. We will see all of the terminals trend to VFR
no later than late this afternoon. Skies should then clear with
the low level flow turning offshore overnight.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 10 AM this morning to 11 PM EST this
     evening for LMZ844>849.

&&

$$

DISCUSSION...NJJ
AVIATION...NJJ