421
FXUS63 KGRR 010439
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1139 PM EST Sun Nov 30 2025

.KEY MESSAGES...

- Potential for a narrow high impact snow band late Mon/Mon night

- Periodic snow chances with below average temperatures this week

&&

.DISCUSSION...
Issued at 305 PM EST Sun Nov 30 2025

- Potential for a narrow high impact snow band late Mon/Mon night

We will be holding on the the lingering Winter Weather Advisory for
the lakeshore and Kalamazoo County through the 7 pm expiration time.

We will be issuing a Winter Storm Watch for Oceana, Muskegon, and
Ottawa counties for Monday afternoon and Night for a potentially
impactful narrow heavy band of snow.

Lake effect snow showers in the advisory area has remained
formidable as expected with visibilities under the snow showers
dropping to below a mile at times. They have been a bit heavier in
the area of a noticeable sfc trough dropping down the lakeshore, and
near South Haven as of 1930z. We remain under cyclonic flow aloft
lingering in the wake of last night`s system, and an additional
short wave is heading toward the area in the next few hours.

We will see the jet core lift NE of the area, and see inversion
heights drop significantly. A nice upper ridge will be heading
toward the area, and a corresponding sfc ridge will move over the
area tonight, bringing light winds and some partial clearing away
from the lakeshore. There may be a few snow showers right along the
lake, but a likely developing land breeze with the fresh snow pack
and light winds combined with the lake should push the snow showers
mainly offshore.

The land breeze could be the basis for some localized high impact
snow showers by Monday afternoon for portions of the lakeshore. The
light wind regime and land breeze over the lake is likely to produce
a convergence band over the east side of the lake. These light wind
scenarios will sometimes produce meso-lows, which the hi-res models
are showing happening late tonight and Monday morning.

We then see this convergent band lift north along the lakeshore as a
southerly component develops with the ridge building east, and with
lower pressures over the warmer lake. This will bring some lake
effect snow showers back in over the lakeshore by late morning, most
likely somewhere between Holland and Pentwater where the lakeshore
juts out into the lake a bit given a flow from the SSW. Nothing too
heavy through noon.

After noon however, we will see the approach of another stronger
short wave from the west. We will see a good deal of mid-upper level
moisture stream in over the area. This moisture aloft will help to
seed the ongoing lake effect band. This moisture, combined with
plenty of remaining instability (delta t`s of mid to upper teens C),
and fairly strong forcing and rising inversion heights has the
potential to produce a very strong narrow band of heavy snow showers
beginning late Monday afternoon, and peaking during the late evening
and overnight hours Monday night.

There is a very good clue of this happening with just about all of
the hi-res data, and even the lower res synoptic models. One could
even say there is even some good agreement that somewhere between
Holland and Pentwater could see a foot plus of snow in a localized
manner. Where exactly this happens, and how much falls remains
uncertain with a mesoscale feature that hasn`t even developed yet.
This band has the potential to drop 1-3 inches/hour for a few
hours at any one location if it comes to fruition.

To give this event some attention, but not be irresponsible with
potential snow amounts, a Winter Storm Watch seems like the best way
to go right now, and to try to hammer home there is some localized
potential. As run to run consistency may continue, and solutions
hone in on the exact evolution and placement of this, a warning is
likely to be issued.

Elsewhere away from this band and any lake enhancement, most
locations will see an inch or two at most from this wave before it
ends Tuesday morning.

- Periodic snow chances with below average temperatures this week

The upper level pattern characterized by broad troughing, and the
flow from the NW will continue to dominate through the next week.
This will ensure that the region sees temperatures remain below
average for the most part, along with unsettled weather in the form
of periodic snow showers.

Right now, it looks like much of Tuesday should be quiet as ridging
builds in behind the departing system for Monday/Monday night. Even
lake effect should be fairly quiet with temperatures aloft modifying
along with inversion heights dropping with the ridge approaching.

The next chance of snow showers will increase on Wednesday as the
next short wave drops in from the NW. This will bring snow showers
then into Wednesday night, before they taper off as a stronger
Canadian ridge builds overhead by Thursday.

This pattern will generally repeat with systems coming in somewhere
around Friday night/Saturday, and Saturday night/Sunday. The timing
with these later systems is very much likely to change on any
differences that happen with the previous systems.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1138 PM EST Sun Nov 30 2025

VFR conditions will prevail through Monday morning then snow will
spread across Lower Michigan from the southwest in the afternoon.
Conditions will drop quickly to IFR, especially at MKG where
intense lake effect snow could bring several hours of IFR and LIFR
conditions. IFR conditions will prevail from 00Z to 06Z at most
places in light to moderate snow.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Watch from Monday afternoon through Tuesday morning
     for MIZ043-050-056.
MARINE...Small Craft Advisory until midnight EST tonight for LMZ844>849.

&&

$$

DISCUSSION...NJJ
AVIATION...Ostuno