612
FXUS63 KGRR 201146
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
646 AM EST Tue Jan 20 2026
.KEY MESSAGES...
- Gradually Improving Conditions Today
- Significant Lakeshore Snow Possible Wednesday Morning
- Episodic Lake Effect Snow Wednesday into Friday
- Rare and Potentially Near Record-Setting Cold This Weekend
&&
.DISCUSSION...
Issued at 316 AM EST Tue Jan 20 2026
- Gradually Improving Conditions Today
Current plan is to expire the Winter Storm Warning scheduled at 7
AM. Water vapor imagery indicates an approaching subtle upper PV
lobe that will likely reinvigorate LES a bit just prior to the
expiration time. The GRR WSR-88D VWP suggests inversion heights
still a respectable 6 kft AGL near the leading edge of the lake
plume. Visibilities at the lakeshore are well above a mile at this
time, but could see them dropping briefly as inversion heights
get a slight boost. Surface observations show the leading edge of
the lake modified plume just west of a South Bend to Kalamazoo
line. Flow is already quite confluent along this boundary and
there could be an FGEN-aided uptick in snow intensity for this
particular region in the next couple hours; if this overperforms,
we might have to consider a local extension of the warning.
Farther inland, had considered cancelling the winter weather
advisory early, but we are just now starting to some more
organization and inland penetration of LES bands compared to just
a couple hours ago so travel hazards will likely persist a bit
longer even away from the lake.
Regardless of the details, the overarching theme is that travel this
morning will not be fun, given slippery conditions in temperatures
that are cold enough to be largely impervious to conventional road
treatments. Conditions should gradually improve during the day
however.
- Significant Lakeshore Snow Possible Wednesday Morning
Models have been consistent showing an Alberta Clipper approaching
the western Great Lakes and inducing surface cyclogenesis over
south-central Lake Michigan. Not only will there be isentropic
ascent with this, but it also appears that FGEN will become quite
strong along the pre-existing land/lake baroclinic zone. As noted
previously, there is sensitivity to how the surface low sets up,
but it is quite plausible that lakeshore areas of Muskegon...
Ottawa...and perhaps Oceana Counties could see intense snowfall
prior to and during the Wednesday morning commute and totals in
excess of 6 inches are not out of the question. This is a
headline-worthy scenario, but would like to clean the slate of
current headlines first so this will likely become a day shift
decision point.
- Episodic Lake Effect Snow Wednesday into Friday
This period will be characterized by deep cyclonic flow with the
polar jet displaced to the south and a trend towards increasingly
cold 850 mb temperatures. Some model guidance also suggests that
Wednesday night could even feature significant inland penetration
of a dominant LES band in favorable laminar flow. Unfortunately,
the overarching theme of challenging travel conditions will
continue.
- Rare and Potentially Near Record-Setting Cold This Weekend
We still anticipate a powerful arctic front to pass through Thursday
night with manifestly colder temperatures beginning Friday. Highs
in the single digits are looking increasingly likely Friday and
Saturday. Minimum temperatures will be especially impressive
thanks to calm conditions with high pressure centered over the
area and a fresh snowpack. This could be a case where cold weather
advisories are warranted based on temperature alone.
Below normal temperatures are expected to continue into next work
week.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 646 AM EST Tue Jan 20 2026
Key change:
- introduced the next round of snow tonight after 06Z
There was a dominant convergent LES band earlier this morning that
extended east over the LAN terminal towards Pontiac. However, this
band is in the process of dissipating. Occasional IFR visibility
restrictions will occur at LAN as the band undulates over the
terminal before finally dissipating later today. Farther west, we
are seeing an uptick in LES at the AZO and BTL terminals that we
expected to yield occasional IFR visibility restrictions this
morning.
Winds are expected to become gusty areawide after 18Z but will not
be nearly as strong as yesterday. Some clearing will be possible
at the interior terminals this evening. Snow will move in
overnight and be most intense by the lakeshore, especially after
06Z Wednesday. IFR visibility restrictions in snow should be
commonplace by 12Z Wednesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Warning until 7 AM EST this morning for MIZ037-038-
043-044-050-056-057-064-065-071-072.
Cold Weather Advisory until 8 AM EST this morning for MIZ038>040.
Winter Weather Advisory until 7 AM EST this morning for MIZ058-
059-066-067-073-074.
MARINE...Heavy Freezing Spray Warning until 7 AM EST this morning for
LMZ844>849.
Small Craft Advisory until 7 AM EST Wednesday for LMZ844>849.
&&
$$
DISCUSSION...TJT
AVIATION...TJT
NWS GRR Office Area Forecast Discussion
