Marine Weather and Tide Forecast for Copper City, MI

DISCUSSION
Issued at 356 PM EST Fri Dec 12 2025

Synoptic setup across the CONUS this afternoon consists of a broad upper low still in the vicinity of the Maritime Provinces followed by weak ridging over the eastern Great Lakes Region and northeast U.S. This ridging is being broken down by a closed upper low elongated over Ontario. Its associated surface low and accompanying cold front will be the focus of the short term period across Upper Michigan. Farther west, a large ridge continues to build over the West Coast.

So far today, lake effect activity has been light on the radar mosaic. However, latest scans are now showing an uptick over western portions of the forecast area, which coincides well with enhanced q- vector divergence along the aforementioned cold front. Anticipate this enhancement to travel eastward across the U.P. this evening, increasing snow chances across Alger and Luce Counties with it. It is in the wake of this front that conditions will become especially dangerous tonight with 850 mb temperatures sinking into the -20 to -25 C range. This will set up a northwest wind lake effect event through the weekend. As a result, this could put snow totals between the lake effect and frontal passage in the 6 to 8 inch range across the Keweenaw and Alger/northern Schoolcraft/Luce Counties through tomorrow. As mentioned above, the dangerously cold 850 mb temperatures will equate to surface temperatures in the -5 to -10F range across much of the interior west and central U.P. tonight. This combined with 30-40 mph WNW winds will create blowing snow and hazardous travel. Therefore, Winter Weather Advisories remain in effect across the Keweenaw and eastern counties along with a Cold Weather Advisory over Gogebic and Iron Counties where windchill values will plummet to -25 to -20F. Daytime highs Saturday will not recover much, either, with readings only in the single digits above zero across much of the west and central interior U.P. and low teens over the east. Saturday night, expect another dangerously cold night, but temperatures will bottom out just above headline criteria.
Nonetheless, wind chills will still approach -10F over the west and central through Sunday morning.

Further out, after a brief lull late Sunday night, focus will turn to another weak shortwave progged for Monday/Monday night. But, snowfall totals don't look particularily high with additional amounts across the eastern counties in the 1 to 3 inch range. This disturbance will then be replaced by zonal flow through mid-week across the U.P. while the next system tracks across central Canada.
This setup will position the U.P. well for a warmup through Thursday as the forecast area falls in the warm sector of that system. Look for daytime highs from Tuesday through Thursday to top off above freezing for the first time in several weeks.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1224 AM EST Sat Dec 13 2025

IFR and LIFR conditions will continue at CMX and IWD through the TAF period. Lake effect snow showers and windy conditions are expected through tonight and Saturday. The combination of snow and blowing snow will result in reduced visibility, possibly to airport minimums at times for CMX. Very cold temperature profiles will keep snow flakes on the smaller size, further contributing to reduced visibility.

SAW will see mainly MVFR but a period of VFR is expected overnight as the cloud cover breaks. Lake effect snow showers could move into SAW Saturday evening but there is still uncertainty, added a mention with prob30.

MARINE
Issued at 356 PM EST Fri Dec 12 2025

Southwesterly winds will ramp up this afternoon and evening to 25 to 30 kts ahead of an approaching cold front, eventually becoming northwesterly and reaching gale criteria by Sat 00Z across the west- central portions of the lake and after Sat 06Z across the eastern half as well. Along with the frigid airmass will be a heavy freezing spray threat for the entire lake; therefore, both Gale and Heavy Freezing Spray Warnings remain in effect into Sunday morning. The exception will be west of the Keweenaw, where gales and the associated gale warning will drop off after Sat 06Z. The remaining gales will then fall below 20 kts across the east half of the lake as well early Sunday morning.

Further out, southwest winds will increase again to 25 to 30 kts Sunday night into Monday across much of the lake. Gale potential continues for west-central portions of the lake, but the models continue to struggle on the intensity of this event. So, this will continue to be monitored. Then after a lull from Monday evening into Tuesday morning, focus will quickly turn to a stronger event progged for Wednesday/Thursday. Gale potential is already in the 50-70% range for this event.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
Winter Weather Advisory until 7 AM EST this morning for MIZ001>003.

Winter Weather Advisory until 7 PM EST this evening for MIZ006- 007-085.

Cold Weather Advisory until 9 AM CST Saturday for MIZ009-010.

Lake Superior...
Heavy Freezing Spray Warning until 1 AM EST /midnight CST/ Sunday for LSZ162.

Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Sunday for LSZ240>244-263-264.

Gale Warning until 1 AM EST early this morning for LSZ242-243- 263.

Gale Warning until 7 AM EST Sunday for LSZ244>246-248>251- 264>267.

Heavy Freezing Spray Warning until 7 AM EST Sunday for LSZ245- 248>251-265>267.

Lake Michigan...
None.