792
FXUS63 KGRR 040831
AFDGRR
Area Forecast Discussion National Weather Service Grand Rapids MI
330 AM EST Thu Dec 4 2025
.KEY MESSAGES...
- Periods of light snow possible late Friday into Sunday
- Accumulating snow possible with systems Tuesday and Wednesday
&&
.DISCUSSION...
Issued at 330 AM EST Thu Dec 4 2025
- Periods of light snow possible late Friday into Sunday
The last of the light snow associated with the front that came
through yesterday is just about to exit the forecast area as of 330
am this morning. The low level flow will remain from the NW today,
with 850 mb temps down in the negative mid teens C. There is plenty
of over lake instability, however building subsidence will push
inversion heights down. This will result in a small layer of
moisture in the DGZ, which should produce nothing more than
flurries/very light snow showers with trace accumulation.
Our next system will be affecting the forecast area beginning later
Friday and Friday night. The responsible feature for this round of
precipitation is a short wave that is currently over British
Columbia. As has been the pattern for the last few days, this short
wave or clipper system embedded in the NW flow aloft will bring
light precipitation.
This system itself will be moisture starved as it moves over the
area. SW flow ahead of the system will add some moisture and
instability from Lake Michigan to potentially produce a couple of
inches of snow focused on the NW corner of the area. Elsewhere
inland, we are looking at accumulations up to an inch.
After a brief break for most of Saturday after the system moves out
early, the next short wave in the series will dive down Sunday
morning and clip the area. This short wave looks to phase with
another wave coming from the Rockies to bring more light snow to the
area. Amounts with this setup look similar to the Fri/Fri night
event with limited moisture available once again.
- Accumulating snow possible with systems Tuesday and Wednesday
We see a mostly dry period come about Monday as a fairly strong sfc
ridge and confluent flow aloft provide stronger subsidence over the
area. Can`t rule out a few flurries near the lakeshore with 850 mb
temps in the negative mid teens C again. The subsidence will really
limit the degree of saturation of the DGZ to limit snow shower
potential.
We are watching the potential for a couple of impactful systems that
could affect the area on Tuesday and Wednesday. The upper air
pattern looks to amplify a bit as a stronger ridge builds of the
eastern Pacific and Western U.S.. Instead of the rather flat upper
flow from the NW, a couple of stronger short waves will dive SE over
the region.
These short waves will be quick hitting, but will pack a punch. The
first one will have cold enough air for Lake Michigan to potentially
enhance it a bit. The second short wave is forecast to be a tad
further south, but will have some warmer air to work with. There is
enough warmer air that we could see some rain mix in over the far
southern portion of our forecast area.
Timing of these waves/frontal systems 6-7 days out is problematic,
especially in a fast flow like we have. We have an idea though of
some potentially impactful weather that we can fine tune as we get
closer to that period.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1140 PM EST Wed Dec 3 2025
As prefrontal moisture moves eastward, post frontal northwesterly
flow filters in. Light snow at LAN are the vestiges of this warm
front.
Strong northwesterly flow is moving over Western Michigan with
northwest winds at BIV, GRR, MKG, AZO and BTL. That northwest flow
will overtake JXN and LAN by 09Z. MVFR vsbys are possible in light
snow through 10Z. MVFR cigs are possible through 15Z with improving
conditions after.
&&
.MARINE...
Issued at 330 AM EST Thu Dec 4 2025
We have decided to hoist a Gale Warning for the northern marine zone
for late tonight through Friday morning.
A Small Craft Advisory remains in effect through 7 pm this evening
for the entire nearshore. This is associated with the cold air
moving in behind the front that moved through yesterday. Winds will
taper off today, and waves may actually drop off early enough that
the Advisory may be able to be cancelled early.
After a brief break in the wind with a sfc ridge moving by the area,
winds will ramp up tonight ahead of the next system moving toward
the area. The strongest winds will be across the north. There is
some potential that the Gale may be needed for another zone or two,
but the confidence is not there yet.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for
LMZ844>849.
Gale Warning from 10 PM this evening to 10 AM EST Friday for
LMZ849.
&&
$$
DISCUSSION...NJJ
AVIATION...Maczko/Ceru
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
