A line of thunderstorms over central North Dakota flared up late in the morning of the 10th, and then tracked into northeast North Dakota and northwest Minnesota through the day. These storms initially formed near a stationary front, which stretched from Winnipeg, Manitoba, Canada, to near Bismarck, ND. By noon CST, the front had progressed to a Langdon (ND) to Devils Lake (ND) line. The airmass ahead of the front was hot and humid (at noon CST), with Jamestown (ND) at 86F and Crookston (MN) at 88F. During the early afternoon, an outflow boundary formed over western Grand Forks County and tracked to the east, eventually reaching a Roseau (MN) to Crookston (MN) to Jamestown (ND) line by late afternoon. These storms also had rich moisture up through 850mb and support from the low level jet.

Thunderstorm Wind in NELSON, NORTH DAKOTA
From 10-AUG-07 13:40:00 to 10-AUG-07 13:40:00 (CST-6)
Location: TOLNA
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees were uprooted at Stump Lake Park. One tree limb fell through the roof of the kitchen/cafe at Stump Lake Park. Other trees fell on recreational vehicles in the park.

Thunderstorm Wind in NELSON, NORTH DAKOTA
From 10-AUG-07 14:12:00 to 10-AUG-07 14:12:00 (CST-6)
Location: PETERSBURG
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Large branches were torn down and several houses lost shingles between the communities of Niagara and Petersburg.

Hail in BENSON, NORTH DAKOTA
From 10-AUG-07 11:00:00 to 10-AUG-07 11:00:00 (CST-6)
Location: HESPER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in EDDY, NORTH DAKOTA
From 10-AUG-07 13:00:00 to 10-AUG-07 13:00:00 (CST-6)
Location: SHEYENNE
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A wooden grain bin was pushed off its foundation and several trees were blown down or snapped off. A very old and abandoned barn nearby was also blown down.

Thunderstorm Wind in NELSON, NORTH DAKOTA
From 10-AUG-07 13:26:00 to 10-AUG-07 13:26:00 (CST-6)
Location: TOLNA
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Several large tree limbs were broken off trees in Tolna and in shelterbelts north of town. Shingles were ripped off a barn and tin was blown off a farm shed.

Hail in BENSON, NORTH DAKOTA
From 10-AUG-07 13:20:00 to 10-AUG-07 13:20:00 (CST-6)
Location: FT TOTTEN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in GRAND FORKS, NORTH DAKOTA
From 10-AUG-07 14:25:00 to 10-AUG-07 14:25:00 (CST-6)
Location: LARIMORE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Tree damage was reported from the gusty winds.

Hail in BENSON, NORTH DAKOTA
From 10-AUG-07 13:15:00 to 10-AUG-07 13:15:00 (CST-6)
Location: TOKIO
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A few large hailstones fell with very strong winds. Some small tree branches were also broken down.

Thunderstorm Wind in GRAND FORKS, NORTH DAKOTA
From 10-AUG-07 15:09:00 to 10-AUG-07 15:14:00 (CST-6)
Location: BOLACK
Magnitude: 55.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The wind gusts were measured by a North Dakota DOT RWIS sensor on Interstate 29 at mile point 145.

Tornado in BENSON, NORTH DAKOTA
From 10-AUG-07 13:18:00 to 10-AUG-07 13:20:00 (CST-6)
Location: TOKIO
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This tornado touched down on Black Tiger Bay (in Benson County), about 9 miles southwest of Crary, and tracked about one mile northeast. At this point, it crossed into the open water of Devils Lake, which is in Ramsey County. The tornado continued about another half mile into Ramsey County, giving the tornado a total path length of 1.5 miles over water.

Tornado in RAMSEY, NORTH DAKOTA
From 10-AUG-07 13:20:00 to 10-AUG-07 13:21:00 (CST-6)
Location: CRARY
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This tornado originated 4 miles north-northeast of Tokio in Benson County at 1318 CST. The tornado crossed from Black Tiger Bay in Benson County and continued into the open waters of Devils Lake in Ramsey County (to about 7.5 miles southwest of Crary by 1321 CST). The tornado was viewed by campers at the south end of Black Tiger Bay. Total path length was about 1.5 miles, with about 0.5 miles of the tornado occurring in Ramsey County.

Tornado in NELSON, NORTH DAKOTA
From 10-AUG-07 13:30:00 to 10-AUG-07 13:40:00 (CST-6)
Location: TOLNA
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado tracked intermittently for nearly 4 miles, before ending near Stump Lake Park. A North Dakota Atmospheric Resource Board observer reported seeing a waterspout on southwest Stump Lake. Numerous trees were blown down or uprooted along the path and in Stump Lake Park. At a farm site, one old barn was shifted off its foundation and peeled open. A small shed was destroyed at another farm. Peak winds were estimated at 100 mph.

Hail in BENSON, NORTH DAKOTA
From 10-AUG-07 10:40:00 to 10-AUG-07 10:40:00 (CST-6)
Location: MADDOCK RICES ARPT
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in BENSON, NORTH DAKOTA
From 10-AUG-07 11:40:00 to 10-AUG-07 11:40:00 (CST-6)
Location: FILLMORE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in NELSON, NORTH DAKOTA
From 10-AUG-07 13:55:00 to 10-AUG-07 13:55:00 (CST-6)
Location: MICHIGAN CITY
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A swather was overturned in a field.