A disturbance moving through a warm and unstable air mass produced strong thunderstorms over Lake Superior from the evening of the 4th into the morning of the 5th.

Marine Thunderstorm Wind in MARQUETTE TO MUNISING MI, LAKE SUPERIOR
From 05-JUL-12 04:17:00 to 05-JUL-12 04:25:00 (EST-5)
Location: AU TRAIN
Magnitude: 39.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind gust was measured at the Au Train RWIS site.

Marine Thunderstorm Wind in SAXON HARBOR WI TO BLACK RIVER MI, LAKE SUPERIOR
From 04-JUL-12 17:27:00 to 04-JUL-12 17:30:00 (EST-5)
Location: SAXON HARBOR WI
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Saxon Harbor observing station measured wind gusts to 41 mph.

Marine Thunderstorm Wind in ONTONAGON TO UPPER ENTRANCE OF PORTAGE CANAL MI, LAKE SUPERIOR
From 04-JUL-12 18:50:00 to 04-JUL-12 18:55:00 (EST-5)
Location: KEWEENAW UPR ENT LT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Portage Canal observing site measured wind gusts to 42 mph.

Marine Thunderstorm Wind in HURON ISLANDS TO MARQUETTE MI, LAKE SUPERIOR
From 04-JUL-12 19:40:00 to 04-JUL-12 19:43:00 (EST-5)
Location: BIG BAY POINT LIGHT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The Big Bay observing station measured 41 mph wind gusts.

Marine Thunderstorm Wind in ONTONAGON TO UPPER ENTRANCE OF PORTAGE CANAL MI, LAKE SUPERIOR
From 04-JUL-12 18:15:00 to 04-JUL-12 18:20:00 (EST-5)
Location: BEACON HILL
Magnitude: 49.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gust measured by the Freda observer.

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 04-JUL-12 20:05:00 to 04-JUL-12 20:10:00 (EST-5)
Location: STANNARD ROCK LIGHT
Magnitude: 42.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

Maximum wind gust measured at Stannard Rock.

Marine Thunderstorm Wind in HURON ISLANDS TO MARQUETTE MI, LAKE SUPERIOR
From 05-JUL-12 03:42:00 to 05-JUL-12 03:46:00 (EST-5)
Location: MARQUETTE LIGHTHOUSE
Magnitude: 40.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Coast Guard

Maximum wind gust measured at the Marquette Coast Guard station.

Marine Thunderstorm Wind in MARQUETTE TO MUNISING MI, LAKE SUPERIOR
From 05-JUL-12 03:42:00 to 05-JUL-12 03:46:00 (EST-5)
Location: MARQUETTE LIGHTHOUSE
Magnitude: 40.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Coast Guard

Wind gust measured at the Marquette Coast Guard station.

Marine Thunderstorm Wind in MARQUETTE TO MUNISING MI, LAKE SUPERIOR
From 05-JUL-12 03:45:00 to 05-JUL-12 04:00:00 (EST-5)
Location: SHOT POINT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind gust was measured by the Harvey RWIS site along the Lake Superior shore.

Marine Thunderstorm Wind in BLACK RIVER TO ONTONAGON MI, LAKE SUPERIOR
From 04-JUL-12 16:30:00 to 04-JUL-12 18:15:00 (EST-5)
Location: GULL POINT
Magnitude: 35.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The observer east of Silver City measured occasional 40 mph wind gusts along the Lake Superior shore.

Marine Thunderstorm Wind in BLACK RIVER TO ONTONAGON MI, LAKE SUPERIOR
From 04-JUL-12 17:50:00 to 04-JUL-12 17:55:00 (EST-5)
Location: GULL POINT
Magnitude: 35.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Buoy

Peak wind gust measured at the western Lake Superior buoy 45006.