243
FXUS63 KGRR 011656
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1156 AM EST Mon Dec 1 2025

.KEY MESSAGES...

- Heavy snow north of Grand Haven today/tonight

- Light snow south of I-96 tonight

- Light snow Wednesday, then cold

- Chance of snow next weekend

&&

.DISCUSSION...
Issued at 316 AM EST Mon Dec 1 2025

- Heavy snow north of Grand Haven today/tonight

A winter storm warning is in effect from Ottawa county north this
afternoon and tonight for the potential of heavy snow. An
approaching upper trough will turn boundary layer winds to the
southwest today. Coupled with deep moisture and h8 temperatures
around -11c, an excellent setup for heavy lake effect snow is
developing. Bufkit omega profiles indicate strong lift
intersecting the dgz this afternoon and tonight. Using 850 mb
omega fields as a proxy for lake band location, the prime target
for heavy snow looks to be from Muskegon north into southern
Oceana county this afternoon and moving north into southwest Mason
county tonight. The potential for 6-12 inches of snow exists in
Muskegon and Oceana counties and 4-8 inches in Mason county. We
also issued a winter weather advisory for Lake, Newaygo, and
Ottawa counties for 3-7 inches of snow. Highest amounts will occur
in western Lake, western Newaygo, and northwest Ottawa counties.

Snowfall surrounding the advisory counties will be
minimal...around an inch or so.

Once the trough axis comes through late tonight, the lake bands
will break apart and try to reorient to the northwest-southeast.
However, much drier air will be moving across the lake and lift
will be waning due to differential anticyclonic vorticity
advection (DAVA).

- Light snow south of I-96 tonight

The same trough that will be promulgating the heavy lake effect
snow over the northwest lake shore tonight will also produce light
synoptic snow south of I-96. An inch of snow is possible along the
I-96 corridor and 1-2 inches along I-94 as the trough moves
through. Compared to what we just had yesterday, this isn`t much.
However, 1-2 inches overnight ahead of the morning commute could
make for some slippery travel, so keep that in mind as you plan
your day Tuesday.

- Light snow Wednesday, then cold

A strong cold front will drop south from Canada Wednesday. Models
show a band of light snow accompanying the front. QPF around a
tenth of an inch will result in 1-3 inches of light snow. H8
temperatures drop from -5c Wednesday to -19c by Thursday morning
setting the stage for a cold Thursday and Friday. Highs both days
will only reach the lower to mid 20s, except along the lake shore
where onshore winds may keep temperatures closer to 30.

The high (lake delta t/s in the mid 20s) instability over the lake
won`t be fully realized in the form of lake effect snow due to the
very dry air moving in behind the front.

- Chance of snow next weekend

Another cold front/short wave combination will arrive Friday
night. A 30-50 percent chance of light snow is anticipated with
this system. Most of the ECMWF ensemble members produce snow, but
not all and those that do only paint around a half inch. What the
cold front will do, however, is keep highs well below normal in
the mid 20s.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1155 AM EST Mon Dec 1 2025

Notable Changes to Forecast: Added TEMPO LIFR at MKG for a few
hours this evening with high confidence of a heavy snow band
shifting across the terminal.

Worst conditions through the forecast period will be at MKG where
radar shows a heavy lake effect snow band is developing in the
vicinity of the terminal. IFR and possibly LIFR conditions are
expected for several hours with this band as it persists.
Otherwise, conditions deteriorate after 00z as widespread light
snow spreads over the terminals leading to MVFR/IFR conditions at
the terminals that will last through the rest of the TAF period.
Look for predominantly southerly winds aob 10 knots through the
TAF period.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Warning until 7 AM EST Tuesday for MIZ037-043-050.
     Winter Weather Advisory until 7 AM EST Tuesday for MIZ038-044-
     056.
MARINE...None.

&&

$$

DISCUSSION...04
AVIATION...Thomas