962
FXUS63 KGRR 272038
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
338 PM EST Thu Nov 27 2025

.KEY MESSAGES...

- Lake Effect Snow Continues through Tonight

- Widespread Accumulating System Snow Expected Saturday into
  Sunday

&&

.DISCUSSION...
Issued at 337 PM EST Thu Nov 27 2025

- Lake Effect Snow Continues through Tonight

Our ongoing lake effect event has unfolded according to plan with
significant wind, snow totals that have been modest (4.8 inches at
White Cloud as of this morning) and slippery travel. Earlier
today we tapered the headlines a bit...downgrading the Warnings
to Advisories and ending some of the more inland counties. We are
currently getting the typical diurnal inland surge to the snow
showers due to horizontal roll convection, but we feel after dark
this will contract more towards the lakeshore or at least into
the western couple tiers of counties. The upper cyclonic axis is
pushing back southward this afternoon which is giving a boost to
the lake effect once again. When lake effect snow is occurring
within the cyclonic side of the upper jet it gets a synoptic scale
boost aiding both coverage and intensity usually. We have seen an
uptick in both this afternoon. BUFKIT overviews especially at
MBL, BIV, LWA and BEH show solid depth of moisture at least to
6,000 feet and higher up north to 10,000+ feet tonight. Lift
remains in the DGZ, so lake effect snow will continue unabated
into Friday morning. We are thinking another 1-2 in most spots
within the advisory with 2-4 inch amounts very possible. With
temperatures near of below freezing and trend down into the lower
20s tonight slippery travel will continue. Bottom line, holding
onto the Winter Weather Advisory through the night or 7am Friday.

- Widespread Accumulating System Snow Expected Saturday into
  Sunday

We have gone ahead and issued a Winter Storm Watch from Saturday
morning through Sunday morning. The snow looks to move in through
the course of Saturday morning reaching peak intensity Saturday
afternoon and especially Saturday evening. The scenario remains
consistent in that a Colorado low will move our direction on
Saturday with warm air advection snow breaking out well in advance
of it. The warm air advection/isentropic upglide snow is longer
lasting than most systems. Most lows of this type give us a 6-12
hour burst of waa snow with this being more 12-18 hours. The DGZ
is 5,000-8,000 feet deep which is solid and the lift is very deep
stretching from just off the deck through 20,000 feet. Flake size
will likely be larger with riming and accretion aiding snow
accumulations a bit. We feel 6+ inches will occur over much of the
forecast area, with the the exception being the U.S. 10 corridor
which may come in just below those totals. Right now the heaviest
swath looks to occur from our southwest CWA near Holland and South
Haven through Grand Rapids and Lansing towards Alma. In the
southwest areas near and south and west of GRR totals may exceed 8
inches. We have time to nail down amounts as this is starting out
in the 4th period and lasting into the 5th period. This will be a
widespread, shovel/plow worthy snow.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1255 PM EST Thu Nov 27 2025

West-northwest winds with lake effect snow showers continue into
tomorrow. Expecting snow showers to morph and at times loosely
organize into cells or bands, creating VFR variable IFR conditions
this afternoon into tonight. Ceilings will range between 1,500
and 4,000 feet. Visibility will dip into IFR locally within the
relatively heavier snow bands.

&&

.MARINE...
Issued at 337 PM EST Thu Nov 27 2025

Winds continue to gust to gale force up and down the shoreline
although the trend is definitely down. Our Gale Warning goes until
100am and we have decided to maintain that end time to allow the
evening shift some leeway in case the gales persist a bit longer.
We will need a Small Craft Advisory once we end the Gale Warning
and that will likely need to be carried into Friday evening.

To wrap up this past event...the Southern Lake Michigan Buoy
peaked at 13.5 feet (significant wave height). Significant wave
height correlates to the highest 1/3 of waves rolling through the
buoy. So higher waves existed within the spectrum of what was
occurring out there. In westerly flow we likely had higher waves
in our nearshore waters given 40 more miles of fetch downwind of
the buoy. With our nearshore buoys out for the season we do not
know exactly what the waves peaked at but in the 14-20 foot range
is likely.

In terms of wind, the highest gusts were 63 mph at Big Sable
Point and the Grand Haven Light, 62 mph at the Saugatuck Pier, 61
mph at the St. Joe Pier and 60 at the Muskegon Pier.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 AM EST Friday for MIZ037>039-
     043>045-050-056-064-065-071>073.
     Winter Storm Watch from Saturday morning through Sunday morning
     for MIZ043>046-050>052-056>059-064>067-071>074.
MARINE...Gale Warning until 1 AM EST Friday for LMZ844>849.

&&

$$

DISCUSSION...Duke
AVIATION...CAS
MARINE...Duke