textproduct: Grand Rapids

KEY MESSAGES

- Periods of light snow late Friday and again Sunday

- Accumulating snow possible with systems mid to late week

DISCUSSION

Issued at 312 PM EST Thu Dec 4 2025

- Periods of light snow late Friday and again Sunday

As noted previously, we are looking at a brief window of lake effect flurries by the lakeshore this afternoon thanks to a thin layer of convective cloudiness in the DGZ. Surface observations and satellite indicate a land breeze induced convergence band that is slowly pushing offshore between Little Sable Point and Holland, which will similarly displace the area of flurries offshore.

No changes in expectations regarding the next system beginning later Friday and Friday night. The 04/12Z HRRR looks scary in terms of forecast reflectivity during this time, especially over Lake MI, but this is likely related to the HRRR's Thompson microphysics scheme that has a penchant for creating water-coated crystals. This yields large simulated reflectivity, but not necessarily large precipitation rates. Best accumulations still look to be over the northwest forecast area. Lake Michigan, being substantially warmer than the surrounding coastal areas, will be able to induce a thermal pressure trough that could enhance convergence along the eastern lakeshore, but even with this in play, we are dealing with limited moisture, sub-optimal crystal growth, and therefore modest accumulations.

Farther south, along and south of Grand Rapids, there is a signal for brief freezing drizzle Friday night towards midnight that, from a time of day/week perspective, may pose limited risks, but could still be sneaky in terms of causing slippery travel on overpasses and other exposed areas.

Our next accumulating snow episode arrives Sunday morning. This will be associated with somewhat more phasing between the northern and southern streams. However, it appears that the best PV forcing manages to bifurcate our area, meaning limited snowfall accumulations for much of southwest Lower MI, albeit a better chance for some snow along and south of I-96 compared to Friday night.

- Accumulating snow possible with systems mid to late week

As noted previously, we expect at least one potentially impactful system towards mid-week with a seasonably deep surface low expected to cross Lower MI around Wednesday. Any time a surface low is forecasted to cross directly over the forecast area, this often sets the stage for a potentially diverse and complex precipitation type forecast that is also highly susceptible to change based on the track of the surface low. This system is no exception and will be a chief focus for concern in the coming days.

There is a signal for yet another shortwave trough and round of winter precipitation towards the end of the work week - but all we can really say now is that the latter half of the week looks to be unsettled with perhaps a favoring of more lake effect by the weekend.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1221 PM EST Thu Dec 4 2025

VFR conditions will continue through Friday morning. Winds will shift southwest overnight with some gusts near Lake Michigan over 20 knots beginning late tonight. Areas of LLWS can be expected across parts of western Lower Michigan late tonight into Friday morning.

MARINE

Issued at 312 PM EST Thu Dec 4 2025

Have maintained the Gale warning and added a Small Craft Advisory for all remaining marine zones to the south that will last well into Saturday. It still looks like the Whitehall to Pentwater region immediately south of the Gale warning could see 2-3 hours of gale conditions tonight, but this is a pretty borderline situation and have therefore elected to leave things as is for now.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory from 10 PM this evening to 7 PM EST Saturday for LMZ844>848. Gale Warning from 10 PM this evening to 10 AM EST Friday for LMZ849.