075
FXUS63 KGRR 012325
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
625 PM EST Mon Dec 1 2025

.KEY MESSAGES...

- Localized heavy lake enhanced snow continues

- Light snow tonight /mainly south/

- Below normal temps with additional snow chances rest of week

&&

.DISCUSSION...
Issued at 310 PM EST Mon Dec 1 2025

- Localized heavy lake enhanced snow continues

Localized heavy lake enhanced snow continues this afternoon from
Grand Haven north to near Muskegon. This snow event has been
reasonably well handled /at least thus far/ by high resolution
models. It is being driven by a persist low level convergent zone,
coupled with respectable over-water instability /featuring water
temps near +9C and 850 mb temps around -10C/. WSW-ENE oriented
snow band is drifting northeast as boundary layer winds become
S-SW. Snow will likely increase further in the coming hours as
mid-upper moisture streams in overhead. Though most of the
synoptic snow from this energy aloft will remain south of MKG and
vicinity, the lake enhanced snow should increase due to seeder-
feeder processes.

High resolution guidance - including HREF/HRRR/NAM - suggest
convergent zone will drift slowly northward tonight...likely exiting
Ottawa county by early evening and then impacting Oceana/Muskegon
and eventually Mason counties /though confidence is dwindling that
Mason county will receive big impacts/. Made a late decision to put
Ottawa county back into the Winter Storm Warning, given ongoing
heavy snow in Grand Haven and how slow the snow has been to drift
north. With focused lift within the dendritic growth zone,
guidance supports 70-80% chance of exceeding 8 inches near the
coast /particularly Muskegon and Oceana counties/. Typical of lake
induced snow, spatial variability will be great and if band
becomes stationary, local accumulations could *greatly* exceed 8
inches.

- Light snow tonight /mainly south/

Mid level impulse over the Central Plains late this afternoon
will race across the Ohio Valley to mid Atlantic states by early
Tuesday. Associated snowfall will spread into the Ohio Valley and
lower Great Lakes late this afternoon and tonight, and impact much
of the GRR forecast area. Limited forcing should preclude much
more than 1-2 inches... mainly south /and away from Lake Michigan/.
This light snow will end by daybreak Tuesday.

- Below normal temps with additional snow chances rest of week

As winds turn NW on Tuesday behind tonight`s system, lingering snow
showers along the lake shore should quickly diminish and push
inland. Little additional accumulation expected.

The remainder of the work week and into next weekend will feature
clipper like systems moving rapidly eastsoutheast out of Canada
and across the Great Lakes region. These features may provide
additional bouts of snow and/or lake enhanced snow, as well as
reinforcing pushes of colder air. The first system will pass about
Wednesday, and bring /sharply colder air/ for Thursday, when
highs will only be around 20F -- easily some of the coldest air
of the season thus far. Another system will impact the region
about Saturday. High temperatures Wednesday through next weekend will
generally be in the 20s to lower 30s, some 10-15F below normal
for the first week of December.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 625 PM EST Mon Dec 1 2025

For MKG... A band of heavy snow is leading to LIFR/VLIFR visbys
and will persist for the next few hours. Then, the band shifts
north of the terminal supporting conditions improving to IFR. The
best moisture begins to pull away after 12z leading to conditions
improving to MVFR, with snow winding down in the early in the
afternoon. MVFR ceilings will persist until the end of the TAF
period.


For AZO, BTL, GRR, JXN, and LAN... Conditions will deteriorate
over the next several hours as light snow moves in with widespread
IFR by 02-03z. This comes with the caveat that the speed for the
low-levels to saturate Snow continues until around 08-09z before
pulling away leaving IFR ceilings and MVFR fog across the
terminals. It will take until early afternoon for conditions to
improve to the point where ceilings can climb to MVFR.

&&

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

&&

$$

DISCUSSION...Smith
AVIATION...Thomas