684
FXUS63 KGRR 291809
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
109 PM EST Sat Nov 29 2025

.KEY MESSAGES...

- Heavy snow today and tonight

- Cold next week with snow chances

&&

.DISCUSSION...
Issued at 306 AM EST Sat Nov 29 2025

- Heavy snow today and tonight

A widespread moderate to heavy snow event is about to unfold
across the region. Winter storm warning have been issued for all
but the northern row of counties where a winter weather advisory
is in effect. No changes to the headlines expected.

Surface obs indicate the Colorado low is now over southwest
Kansas. Radar shows a leading edge of showers/storms from
southwest Missouri south into Texas. From mid Missouri northward,
the precipitation is snow and the leading edge is crossing
Illinois. We`ll see snow spread into the southwest cwa this
morning and move across the cwa by early afternoon.

This storm has a lot going for it and confidence remains high
we`ll see widespread 6-10 inches of snow with locally higher
amounts. As is frequently the case with Colorado lows, they draw
up moisture from the Gulf as they move northeast toward the Great
Lakes. This time, however, there`s so much cold air already in
place, we won`t see a changeover to rain and then back to snow;
this storm will be all snow and a fairly long duration at that. A
strong short wave will also aid in lift this afternoon/tonight as
it moves across northern Illinois.

This system will have a long duration of strong isentropic lift
that will keep the lower atmosphere saturated. The trowal passes
over the heart of the cwa this evening which is when we should see
the heaviest snowfall. The GFS, HRRR, NamNest, and RAP all show
7-10 inches of snow for GRR, 9-12 near Kalamazoo and 6-8 near
Lansing by Sunday morning.

Bufkit profiles reveal a large dgz with lift throughout giving
credence to the idea of heavier snowfall.

Initially, northeast winds 10 to 20 mph with gusts to 25 mph today
will become northwesterly at 15 to 30 mph Sunday. Drifting across
north-south roads Sunday could become and issue. This is a storm
that will produce travel impacts, even after the snow diminishes
Sunday morning.

Once the surface low passes by Sunday morning and boundary layer
winds become northwesterly, lake effect snow will develop and
impact mainly the southwest cwa through Sunday afternoon.

- Cold next week with snow chances

ECMWF ensembles show highs in the mid to upper 20s for much of
the next week, which is several degrees below normal. Monday night
and Wednesday night we could see more snow as a couple of upper
troughs swing through the Great Lakes; additional accumulations
possible.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 108 PM EST Sat Nov 29 2025

Low pressure is centered in South Central Iowa as we approach
18z. Widespread snow is occurring to the east of the low across
Iowa, Wisconsin and Illinois. The eastern edge of the snow has
pushed through all of Southwest Lower Michigan with all 6 TAF
sites in the area now snowing.

Conditions will continue to deteriorate as we work through the
remainder of the afternoon and into the evening hours. Regional
radar loops show a surging large band of heavy snow encompassing
much of Northern Indiana and Northern Illinois stretching back
into Iowa. This band of snow will surge into the TAF sites this
afternoon and remain parked over the area during the evening hours
and into tonight. The heaviest snow at the bulk of the TAF sites
will fall between 22z and 07z. Snowfall rates of 0.50" to 1.00"
per hour are anticipated during that time frame. Conditions have
reached IFR at most TAF sites with a trend towards LIFR and VLIFR
as we work into the evening.

Conditions will try to improve late in the TAF period between 12z
and 18z as the system snow will be exiting to the east. We should
improve to MVFR during this time.

&&

.MARINE...
Issued at 306 AM EST Sat Nov 29 2025

We issued a small craft advisory for this morning through Sunday
morning and a gale watch Sunday morning through Sunday evening.
Strong low pressure moving through the region will cause the
pressure gradient to tighten, especially on the back side as it
moves away and high pressure moves in.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 10 AM EST Sunday for MIZ037>040.
     Winter Storm Warning until 10 AM EST Sunday for MIZ043>046-
     050>052-056>059-064>067-071>074.
MARINE...Small Craft Advisory until 10 AM EST Sunday for LMZ844>849.
     Gale Watch from Sunday morning through Sunday evening for
     LMZ844>849.

&&

$$

DISCUSSION...04
AVIATION...Duke
MARINE...04