A cold front moving through a warm and unstable airmass produced a line of strong to severe thunderstorms across much of Lake Superior from late evening on the 1st into the early morning of the 2nd.

Marine Thunderstorm Wind in BLACK RIVER TO ONTONAGON MI, LAKE SUPERIOR
From 01-JUL-11 21:50:00 to 01-JUL-11 21:55:00 (EST-5)
Location: ONTONAGON LIGHT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A measured gust recorded by the Ontonagon GLOS site.

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 01-JUL-11 21:50:00 to 01-JUL-11 21:55:00 (EST-5)
Location: ONTONAGON
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A measured gust recorded by the Ontonagon GLOS site.

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 01-JUL-11 22:10:00 to 01-JUL-11 22:15:00 (EST-5)
Location: UPPER ENTRANCE PORTAGE CANAL
Magnitude: 38.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Wind gust measured by the spotter in Freda.

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 01-JUL-11 22:30:00 to 01-JUL-11 22:35:00 (EST-5)
Location: UPPER ENTRANCE PORTAGE CANAL
Magnitude: 39.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Portage Canal GLOS site.

Marine Thunderstorm Wind in UPPER ENTRANCE OF PORTAGE CANAL TO MANITOU ISLAND MI 5NM OFFSHORE TO US/CANADIAN BORDER, LAKE SUPERIOR
From 01-JUL-11 22:30:00 to 01-JUL-11 22:35:00 (EST-5)
Location: UPPER ENTRANCE PORTAGE CANAL
Magnitude: 39.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Portage Canal GLOS site.

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 01-JUL-11 23:00:00 to 01-JUL-11 23:05:00 (EST-5)
Location: ROCK OF AGES LIGHT
Magnitude: 36.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

Gust measured by the Rock of Ages C-MAN station.

Marine Thunderstorm Wind in UPPER ENTRANCE OF PORTAGE CANAL TO MANITOU ISLAND MI 5NM OFFSHORE TO US/CANADIAN BORDER, LAKE SUPERIOR
From 01-JUL-11 22:54:00 to 01-JUL-11 22:59:00 (EST-5)
Location: PASSAGE ISLAND LIGHT
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

Gust measured by the Passage Island C-MAN station.

Marine Thunderstorm Wind in MANITOU ISLAND TO MARQUETTE MI BEYOND 5NM FROM SHORE, LAKE SUPERIOR
From 01-JUL-11 22:47:00 to 01-JUL-11 22:52:00 (EST-5)
Location: MANITOU ISLAND
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

The Keweenaw County Sheriff reported around 40 trees uprooted or snapped off just west of Copper Harbor.  The trees ranged in diameter from 6 to 18 inches.

Marine Thunderstorm Wind in POINT ISABELLE TO LOWER ENTRANCE OF PORTAGE CANAL MI, LAKE SUPERIOR
From 01-JUL-11 22:45:00 to 01-JUL-11 22:50:00 (EST-5)
Location: TRAVERSE BAY
Magnitude: 35.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Grand Traverse Bay GLOS site.

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 01-JUL-11 23:29:00 to 01-JUL-11 23:34:00 (EST-5)
Location: STANNARD ROCK LIGHT
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

Gust measured at the Stannard Rock C-MAN site.

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 01-JUL-11 23:14:00 to 01-JUL-11 23:24:00 (EST-5)
Location: MARQUETTE
Magnitude: 35.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Several 40 mph gusts measured at the Big Bay GLOS site.

Marine Thunderstorm Wind in GRAND MARAIS TO WHITEFISH POINT MI, LAKE SUPERIOR
From 02-JUL-11 01:10:00 to 02-JUL-11 01:15:00 (EST-5)
Location: GRAND MARAIS LIGHT
Magnitude: 37.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Grand Marais GLOS site.

Marine Thunderstorm Wind in GRAND MARAIS MI TO WHITEFISH POINT MI 5NM OFFSHORE TO THE US/CANADIAN BORDER, LAKE SUPERIOR
From 02-JUL-11 01:10:00 to 02-JUL-11 01:15:00 (EST-5)
Location: GRAND MARAIS
Magnitude: 37.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Grand Marais GLOS site.

Marine Thunderstorm Wind in UPPER ENTRANCE OF PORTAGE CANAL TO MANITOU ISLAND MI 5NM OFFSHORE TO US/CANADIAN BORDER, LAKE SUPERIOR
From 01-JUL-11 22:47:00 to 01-JUL-11 22:52:00 (EST-5)
Location: COPPER HARBOR
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The Keweenaw County Sheriff reported around 40 trees uprooted or snapped off just west of Copper Harbor.  The trees ranged in diameter from 6 to 18 inches.

Marine Thunderstorm Wind in EAGLE RIVER TO MANITOU ISLAND MI, LAKE SUPERIOR
From 01-JUL-11 22:47:00 to 01-JUL-11 22:52:00 (EST-5)
Location: COPPER HARBOR
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The Keweenaw County Sheriff reported around 40 trees uprooted or snapped off just west of Copper Harbor.  The trees ranged in diameter from 6 to 18 inches.

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 01-JUL-11 22:02:00 to 01-JUL-11 22:07:00 (EST-5)
Location: ROCK OF AGES LIGHT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: C-MAN Station

Gust measured at Rock of Ages C-MAN station.

Marine Thunderstorm Wind in POINT ISABELLE TO LOWER ENTRANCE OF PORTAGE CANAL MI, LAKE SUPERIOR
From 01-JUL-11 22:47:00 to 01-JUL-11 22:52:00 (EST-5)
Location: POINT ISABELLE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The Keweenaw County Sheriff reported numerous trees down in around 40 trees uprooted or snapped off just west of Copper Harbor.  The trees ranged in diameter from 6 to 18 inches.  Portions of Calumet also sustained tree and some roof damage 10-15 minutes earlier.

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 02-JUL-11 01:10:00 to 02-JUL-11 01:15:00 (EST-5)
Location: GRAND MARAIS
Magnitude: 37.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Gust measured by the Grand Marais GLOS site.