885
FXUS63 KGRR 092026
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
326 PM EST Tue Dec 9 2025

.KEY MESSAGES...

- Clipper Brings Snow/Mix Tonight and Wednesday

- Snow Chances Late Week

- Weekend Arctic Blast

&&

.DISCUSSION...
Issued at 258 PM EST Tue Dec 9 2025

- Clipper Brings Snow/Mix Tonight and Wednesday

The Winter Weather Advisory for tonight and Wednesday was
expanded south to the I-96 corridor to account for a slight
southward shift of the track of the surface low and its resulting
increase in snow totals and potential for icing of surfaces for
several hours in this area.

Current radar and obs upstream show an area of light to moderate
snow across Minnesota and Wisconsin along an axis of mid-level
frontogenetical forcing. This area is forecast to move into Lower
Michigan and intensify this evening, aided by the left exit
region of a jet core as a shortwave trough consolidates with a
pair of upper lows across SE Canada.

The hi-res models show mesoscale banded precip with the potential
for snowfall rates of inch an hour between 10 PM and 3 AM. This
should result in 3 to 5 inches of snow across the northern zones
by Wednesday afternoon. Snow will mix with rain around 3 AM along
I-96 and south, with 2 to 4 inches total across I-96 and lesser
amounts south, possibly an inch or two along I-94.

Icing of untreated roads, especially dirt roads, could be a
problem tonight into Wednesday morning along the I-96 corridor as
air temperatures just above freezing may not be warm enough to
overcome the residual cold of pavement and soil after several days
of arctic air.

The surface low moves east in the afternoon with a trailing area
of mid-lvel f-gen and a weak trowal feature providing enough lift
to add another inch of snow before ending. Cyclonic flow and cold
advection strengthens in the afternoon with temperatures falling
below freezing again. Light lake effect snow showers possible, but
limited by inversion heights around 5 kft.

- Snow Chances Late Week

Longwave pattern continues to feature the arctic drape across the
northern Rockies to the NE CONUS, with fast moving shortwave
troughs minoring out as they zip east-southeast. We will have the
chance for light snow on Friday and Saturday as an arctic front
and polar jet axis influence weather across the Great Lakes. Wind
chill temperatures could approach 10 below zero over the weekend.

- Weekend Arctic Blast

A vast area of arctic air pooling across northwest Canada surges
southeast by the weekend, with a lobe of the polar vortex reaching
northern Lower Michigan by Sunday. 850 MB temperatures plunge
below -20C and should result in high temperatures being confined
to the teens on both Saturday and Sunday, with lake effect
"diamond dust" as the DGZ is near the surface.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1259 AM EST Tue Dec 9 2025

MVFR dominates the pattern this afternoon with gust southeasterly
winds. Winds have gusted upwards of 33kts. Expect this gusty winds
to continue with a lull in the winds between 22Z to 03Z.

Snow is still expected to move in from the southwest between 00Z
to 03Z tonight with a transition to a rain/snow mix to rain along
and south of the I-96 corridor into Wednesday morning. Freezing
rain remains possible during the transitions. Snow is expected
again early Wednesday morning with a transition from rain to snow.
IFR cigs are expected after 00Z with ceilings improving slowly
tomorrow.

Ceilings will improves from the Northwest to southeast behind the
front late tomorrow morning, early afternoon. Vsbys will remain
MVFR and lower with periods of IFR vsbys possible with Fog/mist
due to the rain/snow transition around 14Z Wednesday. LLWS is
expected after 07Z until around 12Z due to the approaching front
at GRR, AZO, BTL, LAN and JXN.

&&

.MARINE...
Issued at 258 PM EST Tue Dec 9 2025

No changes to the SCA or Gale Warning. Southwest gales expected
tonight into Wednesday. Winds will shift to the northwest
Wednesday afternoon with wave heights 7 to 12 feet. Gales subside
Wednesday evening with Small Craft Advisory conditions likely
through at least Thursday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from 10 PM this evening to 4 PM EST
     Wednesday for MIZ037>040-043>046-050>052-056>059.
MARINE...Small Craft Advisory until midnight EST tonight for LMZ844>847.
     Gale Warning from midnight tonight to 7 PM EST Wednesday for
     LMZ844>847.
     Small Craft Advisory until 7 AM EST Wednesday for LMZ848-849.
     Gale Warning from 7 AM to 7 PM EST Wednesday for LMZ848-849.

&&

$$

DISCUSSION...Ostuno
AVIATION...Ceru
MARINE...Ostuno