Forcing and instability ahead of a low pressure system moving across the region spawned strong to severe thunderstorms and isolated waterspouts over portions of Lake Superior during the afternoon of the 5th.

Marine Thunderstorm Wind in MANITOU ISLAND TO MARQUETTE MI AND W OF GRAND MARAIS MI TO US/CANADIAN BORDER BEYOND 5NM OF SHORE, LAKE SUPERIOR
From 05-OCT-23 14:40:00 to 05-OCT-23 14:50:00 (EST-5)
Location: STANNARD ROCK LIGHT
Magnitude: 68.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

The Stannard Rock Light C-MAN station recorded a thunderstorm wind gust of 78 mph on the afternoon of the 5th.  Given the instability over the lake waters, there was speculation that a waterspout may have formed from the thunderstorm, possibly causing the strong gusty winds, but there was no way to officially confirm this.

Waterspout in SAXON HARBOR WI TO UPPER ENTRANCE OF PORTAGE CANAL MI 5NM OFFSHORE TO US/CANADIAN BORDER INC ISLE ROYAL NP, LAKE SUPERIOR
From 05-OCT-23 13:20:00 to 05-OCT-23 13:25:00 (EST-5)
Location: OUTER ISLAND LIGHT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mariner

The American Spirit bulk carrier observed two waterspouts approximately 30 miles north-northwest of Porcupine Mountains State Park over the open waters of Lake Superior.  Information was relayed from the Duluth Port Meteorological Officer and time and location of the report was estimated from radar.

Marine Thunderstorm Wind in POINT ISABELLE TO LOWER ENTRANCE OF PORTAGE CANAL MI, LAKE SUPERIOR
From 05-OCT-23 15:25:00 to 05-OCT-23 15:35:00 (EST-5)
Location: KEWEENAW LOWER ENTRANCE LIGHT
Magnitude: 42.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mariner

The State of Michigan vessel reported a max thunderstorm wind gust to 48 mph in Keweenaw Bay.

Marine Thunderstorm Wind in EAGLE RIVER TO MANITOU ISLAND MI, LAKE SUPERIOR
From 05-OCT-23 15:55:00 to 05-OCT-23 16:05:00 (EST-5)
Location: COPPER HARBOR
Magnitude: 47.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Copper Harbor ASOS measured a thunderstorm wind gust to 54 mph.

Marine Thunderstorm Wind in SAXON HARBOR WI TO UPPER ENTRANCE OF PORTAGE CANAL MI 5NM OFFSHORE TO US/CANADIAN BORDER INC ISLE ROYAL NP, LAKE SUPERIOR
From 05-OCT-23 14:40:00 to 05-OCT-23 14:50:00 (EST-5)
Location: ROCK OF AGES LIGHT
Magnitude: 48.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

The Rock of Ages Light C-MAN station measured a peak thunderstorm wind gust of 55 mph.

Marine Thunderstorm Wind in UPPER ENTRANCE OF PORTAGE CANAL TO MANITOU ISLAND MI 5NM OFFSHORE TO US/CANADIAN BORDER, LAKE SUPERIOR
From 05-OCT-23 15:45:00 to 05-OCT-23 15:55:00 (EST-5)
Location: PASSAGE ISLAND LIGHT
Magnitude: 55.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

The Passage Island Light C-MAN station measured a peak thunderstorm wind gust of 63 mph.

Marine Thunderstorm Wind in MANITOU ISLAND TO MARQUETTE MI AND W OF GRAND MARAIS MI TO US/CANADIAN BORDER BEYOND 5NM OF SHORE, LAKE SUPERIOR
From 05-OCT-23 16:55:00 to 05-OCT-23 17:05:00 (EST-5)
Location: STANNARD ROCK LIGHT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

The Stannard Rock Light C-MAN station measured a peak thunderstorm wind gust of 41 mph.