Marine Weather and Tide Forecast for Copper Harbor, MI

DISCUSSION
Issued at 302 AM EST Sat Feb 28 2026

Early morning RAP analysis and GOES water vapor imagery place the UP underneath a shortwave trough embedded in a broader troughing pattern across the Upper Midwest and central Canada. The strong clipper system now at 985 mb over the southern tip of James Bay extends a cold front down into northern Lower MI. CAA and pressure rises continue to support blustery conditions over the east and near Lake Superior through this morning, but frequent gusts exceeding 45 mph outside the east are no longer expected. These gusts drop off around 4 am EST this morning as the strong LLJ quickly departs; maintained the wind headlines as inherited. With 850mb temps lowering to between -19C to -23C, coldest over northeastern Lake Superior, LES over the northwest wind snowbelts sets up.
Thermodynamic profiles leave much to desire, so accumulation today and tonight are anticipated to be on the low side with limited if any impacts. Forecast amounts include a dusting to 2 inches in the west and up to 4 inches over the east by 7 AM EST Sunday morning.
Also today, a weak disturbance tracks to the south, possibly grazing the south with a light dusting to as high as 1 inch (15-24% chance).
Highs today and Sunday will be seasonably cold in the teens to low 20s; overnight lows in the single digits mainly below 0 are expected. Cold headlines are not anticipated given light winds. LES primarily becomes confined to the east on Sunday as high pressure becomes centered over the UP. Low level convergence over the east could offset the drier air and increasing anticyclonic flow, but confidence is low at this point and minor impacts would be isolated.

Zonal flow sets up for next week with systems mainly only grazing the UP the first half. More widespread PoPs, albeit still on the low side (20-40%), set up for the later half of the week as deeper waves and stronger surface lows begin to move into the Upper Midwest.
Particular focus is on the end of the work week when a CO low lifts through. There is plenty of spread yet in the ensemble guidance regarding track, but the 0Z deterministic guidance and the EPS favor a track further to the north. This places the UP largely in the warm sector throughout the event, leaning P-type toward rain. Given the uncertainty yet, a wintry mix is still possible. The pattern next week favors a warm up (65-75% chance for above normal temps per the latest CPC 6-10 day outlook), with highs once again returning to the 40s for many. Lows initially in the upper teens to 20s early next week push near freezing Wednesday/Thursday nights.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
Issued at 642 AM EST Sat Feb 28 2026

MVFR conditions are expected today, becoming VFR tonight. Gusty winds will diminish this morning as a low pressure moves east, away from the U.P. with high pressure building in from the west. Onshore flow will continue to bring lake effect clouds into the area but dry air in the low levels will limit the potential for snow showers, with only a few flurries expected. High pressure will be centered over northern MN by Sunday morning with light winds over the area and clouds scattering out, resulting in VFR conditions.

MARINE
Issued at 302 AM EST Sat Feb 28 2026

Northwest gales of 35-45 kts over the east half quickly diminish this morning as the strong low level jet departs and high pressure builds in from the northwest. Downgraded the east to a Gale Warning through 7 AM EST and canceled the west Gale Warning early. Winds over the west fall below 20 kts by this afternoon with winds around 20-25 kts in the east into the evening. Winds over the east fall below 20 kts tonight, with lakewide winds below 20 kts through Sunday night. As a result, heavy freezing spray diminishes from west to east today. Trimmed up the end time for the eastern zones Heavy Freezing Spray Warning, otherwise maintained those hazards as inherited.

Southerly winds increase on Monday to 20-30 kts ahead of a surface trough Monday night. There is a 15-30% chance for gales to 35 kts over the east and near Isle Royale Monday afternoon and evening.
Winds become northerly and fall below 20 kts Tuesday morning.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ this morning for LSZ162.

Heavy Freezing Spray Warning until 10 AM EST /9 AM CST/ this morning for LSZ240>242-263.

Heavy Freezing Spray Warning until 1 PM EST this afternoon for LSZ243-244-264.

Heavy Freezing Spray Warning until 4 PM EST this afternoon for LSZ245>248-265.

Heavy Freezing Spray Warning until 10 PM EST this evening for LSZ249>251-266-267.

Gale Warning until 7 AM EST this morning for LSZ249>251-266- 267.

Lake Michigan...
None.