159
FXUS63 KGRR 090845
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
345 AM EST Tue Dec 9 2025

.KEY MESSAGES...

- Quick Round of Snow, Freezing Drizzle Possible This Morning

- Another Round of Snow and Rain Tonight into Wednesday

- Reinforcing short of Arctic Air and Snow Showers Fri-Sun

&&

.DISCUSSION...
Issued at 338 AM EST Tue Dec 9 2025

- Quick Round of Snow, Freezing Drizzle Possible This Morning

A quick round of snow will move through this morning bringing around
an inch of snow for most of the area with 2 to 5 inches north of
Grand Haven with the highest amounts north of Muskegon. As snow
tapers off freezing drizzle/light rain could develop between 8am-
1pm. This is due to moisture profile flirting with -8C temperatures.
One factor that could help is dry air toward the surface with breezy
winds. Soundings are not persistent in keeping the low levels
saturated, however the NAM is more aggressive. If freezing
drizzle/light rain develops it will be along and south of the I-96
corridor and bring with it a light glaze of ice creating slick
conditions.

- Another Round of Snow and Rain Tonight into Wednesday

A brief break in wintry weather is expected this afternoon but it
will be short lived as another clipper system swings through the
region tonight into Wednesday. This low will be stronger as seen
in the 250mb upper level divergence and warming temperatures along
with strong warm air advection near the surface with the low
level jet. Positive vorticity advection moves in around 10pm
along with the better moisture. Precipitation is expected to start
out as snow, but strong warm air advection on the south side of
the low is expected to transition the snow to rain. We`ll need to
monitor surface temperatures to see if a brief period of freezing
rain will occur. How far north the rain spreads will depend on the
overall low track. Additionally the track will also impact
snowfall amounts. A slight shift of 50 miles can make a huge
difference in this set up. At this time there is higher confidence
in snowfall amounts of 4 inches or more along and north of the
M-20 corridor with probabilities in the 60 to 90 percent range.
Therefore have issued a Winter Weather Advisory from Oceana to
Isabella County and northward for tonight into Wednesday
afternoon. The 25th to 75th percentile highlight amounts of 3 to 7
inches in this area. If the low tracks further south the advisory
may need to be extended southward. Any rain is expected to
transition back to snow Wednesday morning with snow showers
continuing into the afternoon.

Winds will be quite breezy with this system with gusts from the
southwest around 30 mph expanding from south to north overnight
into Wednesday morning then shifting to the northwest behind the
low late Wednesday morning into the afternoon. This will aid in
reducing visibilities with the snowfall. The northwest flow off of
the lake will also keep some snow shower in the area Wednesday
afternoon and night, however moisture is limited so not expected
much in the way of additional accumulations.

- Reinforcing short of Arctic Air and Snow Showers Fri-Sun

The coldest air of the season so far is showing up in some of the
ensemble guidance over the weekend as another reinforcing clipper
system may impact Michigan by Friday, bringing 850mb temperatures
behind it into the -15C to -20C range Saturday and Sunday. This
would yield high temperatures mainly in the teens to around 20F away
from the lake. Upper low formation around or just north of Lake
Superior is a possibility, with some vort maxes pivoting over the
region which would help with synoptic lift and lake enhanced
snowfall to areas along and west of US 131. This snow will likely be
quite powdery and finer grain. Almost all ECE ensemble members show
accumulating snow for the lakeshore region this weekend.

There are a few interesting takeaways from a global teleconnections
standpoint this month. The weak La Nina pattern continues, and the
Madden Julian Oscillation just moved out of a strong Phase 7 and
decent strength Phase 8, which correlate to colder than normal
temperatures across the northern U.S. Additionally, as we ended
November and moved into December, a sudden stratospheric warming
event occurred which is most easily tracked via a weakening and
reversal of winds at 10mb across 60N latitude. The winds did not
really reverse as they do during major SSW events, but still this
had the effect of weakening the polar vortex and shifting it off the
pole. While we haven`t gotten the full brunt of the polar vortex
here in Michigan, it likely has played some sort of role in
modifying the tropospheric weather pattern across our broader
region. All this to say is that one of the coldest starts to
December on record (top 10 for all climate sites through the first
week) is attributable to some of these factors.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1057 PM EST Mon Dec 8 2025

Recent surface obs indicate widespread VFR conditions across the
terminals. However, radar over Wisconsin shows light snow moving
east. Expect VFR to quickly fall to IFR once the light snow
develops, first at MKG/GRR around 06z and then at LAN/JXN shortly
after 12z. A few hours of FZDZ is possible mixed with light snow
after 12z before the precipitation from west to east early
afternoon.

A few hours of LLWS is anticipated at the I-94 terminals this
morning.

Another round of snow and/or mixed rain/snow is expected after 00z
tonight as the next system moves through.

&&

.MARINE...
Issued at 338 AM EST Tue Dec 9 2025

Gales will taper off after sunrise with Small Craft Advisory
conditions continuing through the day. Strong southwest winds then
move in tonight into Wednesday bringing another period of gales.
Winds will shift to the northwest Wednesday afternoon as the strong
low pressure system shifts east. Wave heights during this time are
expected to be in the 7 to 12 foot range. Gales subside Wednesday
evening with Small Craft Advisory conditions likely through at least
Thursday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 4 PM EST this afternoon for MIZ037-
     043.
     Winter Weather Advisory from 10 PM this evening to 4 PM EST
     Wednesday for MIZ037>040-043>046.
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.
     Gale Warning from 7 AM to 7 PM EST Wednesday for LMZ848-849.
     Gale Warning until 7 AM EST this morning for LMZ849.
     Small Craft Advisory from 7 AM this morning to 7 AM EST
     Wednesday for LMZ849.

&&

$$

DISCUSSION...Hoving/RAH
AVIATION...04
MARINE...RAH