textproduct: Grand Rapids

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 /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1155 AM EST Mon Dec 1 2025

Notable Changes to Forecast: Added TEMPO LIFR at MKG for a few hours this evening with high confidence of a heavy snow band shifting across the terminal.

Worst conditions through the forecast period will be at MKG where radar shows a heavy lake effect snow band is developing in the vicinity of the terminal. IFR and possibly LIFR conditions are expected for several hours with this band as it persists. Otherwise, conditions deteriorate after 00z as widespread light snow spreads over the terminals leading to MVFR/IFR conditions at the terminals that will last through the rest of the TAF period. Look for predominantly southerly winds aob 10 knots through the TAF period.

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.