Marine Weather and Tide Forecast for Pentwater, MI

DISCUSSION
Issued at 306 AM EST Sat Nov 29 2025

- Heavy snow today and tonight

A widespread moderate to heavy snow event is about to unfold across the region. Winter storm warning have been issued for all but the northern row of counties where a winter weather advisory is in effect. No changes to the headlines expected.

Surface obs indicate the Colorado low is now over southwest Kansas. Radar shows a leading edge of showers/storms from southwest Missouri south into Texas. From mid Missouri northward, the precipitation is snow and the leading edge is crossing Illinois. We'll see snow spread into the southwest cwa this morning and move across the cwa by early afternoon.

This storm has a lot going for it and confidence remains high we'll see widespread 6-10 inches of snow with locally higher amounts. As is frequently the case with Colorado lows, they draw up moisture from the Gulf as they move northeast toward the Great Lakes. This time, however, there's so much cold air already in place, we won't see a changeover to rain and then back to snow; this storm will be all snow and a fairly long duration at that. A strong short wave will also aid in lift this afternoon/tonight as it moves across northern Illinois.

This system will have a long duration of strong isentropic lift that will keep the lower atmosphere saturated. The trowal passes over the heart of the cwa this evening which is when we should see the heaviest snowfall. The GFS, HRRR, NamNest, and RAP all show 7-10 inches of snow for GRR, 9-12 near Kalamazoo and 6-8 near Lansing by Sunday morning.

Bufkit profiles reveal a large dgz with lift throughout giving credence to the idea of heavier snowfall.

Initially, northeast winds 10 to 20 mph with gusts to 25 mph today will become northwesterly at 15 to 30 mph Sunday. Drifting across north-south roads Sunday could become and issue. This is a storm that will produce travel impacts, even after the snow diminishes Sunday morning.

Once the surface low passes by Sunday morning and boundary layer winds become northwesterly, lake effect snow will develop and impact mainly the southwest cwa through Sunday afternoon.

- Cold next week with snow chances

ECMWF ensembles show highs in the mid to upper 20s for much of the next week, which is several degrees below normal. Monday night and Wednesday night we could see more snow as a couple of upper troughs swing through the Great Lakes; additional accumulations possible.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 108 PM EST Sat Nov 29 2025

Low pressure is centered in South Central Iowa as we approach 18z. Widespread snow is occurring to the east of the low across Iowa, Wisconsin and Illinois. The eastern edge of the snow has pushed through all of Southwest Lower Michigan with all 6 TAF sites in the area now snowing.

Conditions will continue to deteriorate as we work through the remainder of the afternoon and into the evening hours. Regional radar loops show a surging large band of heavy snow encompassing much of Northern Indiana and Northern Illinois stretching back into Iowa. This band of snow will surge into the TAF sites this afternoon and remain parked over the area during the evening hours and into tonight. The heaviest snow at the bulk of the TAF sites will fall between 22z and 07z. Snowfall rates of 0.50" to 1.00" per hour are anticipated during that time frame. Conditions have reached IFR at most TAF sites with a trend towards LIFR and VLIFR as we work into the evening.

Conditions will try to improve late in the TAF period between 12z and 18z as the system snow will be exiting to the east. We should improve to MVFR during this time.

MARINE
Issued at 306 AM EST Sat Nov 29 2025

We issued a small craft advisory for this morning through Sunday morning and a gale watch Sunday morning through Sunday evening.
Strong low pressure moving through the region will cause the pressure gradient to tighten, especially on the back side as it moves away and high pressure moves in.

GRR WATCHES/WARNINGS/ADVISORIES
MI...Winter Weather Advisory until 10 AM EST Sunday for MIZ037>040.
Winter Storm Warning until 10 AM EST Sunday for MIZ043>046- 050>052-056>059-064>067-071>074.
MARINE...Small Craft Advisory until 10 AM EST Sunday for LMZ844>849.
Gale Watch from Sunday morning through Sunday evening for LMZ844>849.