MICHIGAN — The Great Lakes are flexing their early-winter muscle today as a powerful Arctic blast sweeps across Lake Superior, triggering dangerous conditions for mariners from Isle Royale to Marquette. Waves are already building, winds are strengthening, and by late afternoon, gusts up to 40 knots and waves near 14 feet are expected.
According to the National Weather Service in Marquette, a Gale Warning is in effect from 7 a.m. today until 7 a.m. Thursday, alongside a Heavy Freezing Spray Warning from 7 p.m. tonight through early Thursday morning. Forecasters warn that freezing spray will accumulate at rates exceeding two centimeters per hour, quickly coating decks, masts, and mechanical systems with thick ice.
The warning covers waters from Saxon Harbor, WI, east to Grand Marais, MI, and north to the U.S.–Canadian border, including Isle Royale National Park. Mariners are advised to remain in port or seek safe harbor, as the combination of gale-force winds, freezing spray, and large waves could capsize small craft or render vessels inoperable.
“Operating in heavy freezing spray is hazardous,” the NWS warned, noting that ice accretion could cause catastrophic loss of stability. Even experienced operators may find navigation difficult due to poor visibility and ice buildup on instruments.
By Thursday morning, winds will gradually ease as high pressure builds in, but bitter cold will linger — another reminder that December’s maritime season on Superior leaves no margin for error.
