773
FXUS63 KGRR 292325
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
625 PM EST Mon Dec 29 2025
.KEY MESSAGES...
- Snow Showers and Wind Decrease Through Tonight
- Two Rounds of Light Snow Tuesday and Wednesday
- Turning Quieter for the Weekend
&&
.DISCUSSION...
Issued at 314 PM EST Mon Dec 29 2025
- Snow Showers and Wind Decrease Through Tonight
Snow shower coverage has migrated closer to the lakeshore
this afternoon as the surface low peels away from the region and
1000-700 mb RH and omegas decrease inland while still being
present west of US 131. That said, the strong boundary layer winds
continue to blow bands of snow well inland. Without the synoptic
boost via deeper moisture and lift, purely lake effect snow
showers will be steadiest along the lakeshore counties though the
intensity of the bands will be decreasing. Although consideration
was given to cancellation of inland headlines and a downgrade to
Advisory along the lakeshore, the continuation of snow showers and
blowing snow for a few hours leads to holding course on the
headlines in spite of a lack of heavy accumulations given such
strong winds.
Compensating for lower accumulation rates this evening will be
winds continuing to gust in the 35 to 45 mph range for most areas,
leading to blowing snow in open areas and thus some travel
impacts continuing into the early evening before improving.
Overall, additional snowfall of 1" or less is expected in the
Advisory area and 2" or less in the Warning through 7pm. With the
transient nature of the daytime and early evening bands, expect
variability in accumulations and visibility.
Peak wind gusts today have eclipsed 60 mph at some of our coastal
observing sites, while inland gusts have been 40-50 mph just about
everywhere. The worst of the winds will be in our rear view
mirror as they should decline into the 30-40 mph range by sunset
and then 15-30 mph after that. In terms of snowfall accumulations,
reports this morning indicated 1"-4" mainly along and west of US
131. Additional afternoon and evening accumulations will bring
storm total amounts into the 3"-7" range along/west of US 131 with
some higher amounts possible along the lakeshore.
- Two Rounds of Light Snow Tuesday and Wednesday
There are a couple of midweek systems that will bring some
accumulating snow to most of the region, especially near and west of
US 131. The 18z Tuesday to 06z Wednesday time frame is the first
period of interest. A weak 500 mb shortwave (Canadian Clipper) moves
through Tuesday afternoon with solid 1000-700 mb RH and modest 925-
850mb omegas but very limited lift within the actual DGZ. QPF from
high res CAMs is indicating 0.10"-0.20" along the lakeshore and
0.05"-0.10" inland. With SLRs of 15:1 to 17:1, this should yield
light accums of 1"-3" near and west of US 131 (locally over 3"
across Mason and Oceana Counties) and generally 1" or less east of
there.
The second system moves in New Year`s Eve from late morning into
late night. This system is stronger at 500 mb and hence there is
better synoptic lift moving over the lake, but also there is better
lift within the DGZ. Model QPF looks similar though the highest
amounts are favored near and south of a MKG-GRR-BTL line. Generally
another 1"-3" is forecast in this region with some spots locally
higher mainly across Allegan and Van Buren Counties.
By New Year`s Day, colder temperatures move in with highs ranging
from the upper teens to low 20s. Some light snow showers or flurries
are possible.
- Turning Quieter for the Weekend
Not much in the way of precipitation is currently forecast for the
weekend as upper heights build and temperatures rise a bit into the
upper 20s to low 30s. ENS/GEFS/CMC guidance is all indicating some
500mb troughing trying to develop by the end of the weekend into
early next week, but whether this will be deep enough and cold
enough to support lake effect snow is unclear at this time.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 622 PM EST Mon Dec 29 2025
Lake effect snow continues across the terminals. As the wind
gradually decreases this evening, visibilities will improve.
Ingredients will remain in place to produce lake effect snow
showers through the period, although, warming boundary layer
temperatures and falling inversion heights will result in the
lower visibilities retreating closer to MKG/AZO and perhaps GRR.
Another clipper will move over the region Tuesday and is reflected
in the TAFs via IFR vsbys in -shsn Tuesday afternoon.
&&
.MARINE...
Issued at 313 PM EST Mon Dec 29 2025
Have downgraded the Storm Warning to a Gale Warning through 06z
Tuesday. Wind gusts have slowly been coming down over the
nearshore waters as observed at some of our coastal observation
sites. Wave heights will continue to be impressive with 12 to 15
feet possible into tonight. A couple of light snow producing
systems moving in Tuesday and Wednesday could generate waves of 6
to 10 feet potentially.
&&
.HYDROLOGY...
Issued at 313 PM EST Mon Dec 29 2025
Unusually heavy rain for late December impacted the region
yesterday with 1"-2" near and south of I-96, and this is leading
to river rises across southern Lower Michigan. Most notable is the
Sycamore Creek at Holt which is forecast to come close to flood
stage tonight and thus some minor flooding impacts are possible in
the general vicinity. Elsewhere, rises on rivers such as the
Grand River at Ionia, Maple River at Maple Rapids, Looking Glass
River at Eagle, Thornapple River at Hastings, and the Portage
River at Vicksburg will likely see rises above banks but hold
below flood stage. Exercise caution near rivers as they will be
running much higher than normal following recent rainfall.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Warning until midnight EST tonight for MIZ037>040-
043-044-050-056-064-071-072.
Winter Weather Advisory until midnight EST tonight for MIZ045-
051-057-058-065-066-073.
Wind Advisory until 7 PM EST this evening for MIZ046-052-059-067-
074.
MARINE...Gale Warning until 1 AM EST Tuesday for LMZ844>849.
&&
$$
DISCUSSION...Hoving
AVIATION...04
MARINE...Hoving
HYDROLOGY...Hoving
NWS GRR Office Area Forecast Discussion
