A line of severe thunderstorms developed over southeast Montana on the evening of August 30th, and continued to track across western and central North Dakota. These thunderstorms reached the Devils Lake region just after midnight, producing strong wind gusts and large hail. The storms eventually tracked into northeast North Dakota and the far northwest corner of Minnesota. This was a perfect elevated thunderstorm scenario, with the storms being fed by the low level jet. The greatest core of damage occurred from Grafton (ND) to Donaldson (MN), where strong straight line winds were measured by several mesonet wind sensors.

Thunderstorm Wind in BENSON, NORTH DAKOTA
From 01-SEP-11 00:05:00 to 01-SEP-11 00:05:00 (CST-6)
Location: MADDOCK
Magnitude: 52.00 EG
Reported by: Public

A large tree branch was blown down.

Hail in TOWNER, NORTH DAKOTA
From 01-SEP-11 00:30:00 to 01-SEP-11 00:30:00 (CST-6)
Location: ROCKLAKE
Magnitude: 1.00 
Reported by: Public

The hail was a mixture of nickel to quarter size.

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:15:00 to 01-SEP-11 01:15:00 (CST-6)
Location: ADAMS
Magnitude: 91.00 EG
Reported by: Fire Department/Rescue

A shed was destroyed and two grain bins were blown off slab. Power poles were also blown down. Peak winds were estimated at 105 mph.

Thunderstorm Wind in RAMSEY, NORTH DAKOTA
From 01-SEP-11 00:45:00 to 01-SEP-11 00:45:00 (CST-6)
Location: ST JOE
Magnitude: 52.00 EG
Reported by: Public

The strong wind gusts occurred west of Hampden.

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:39:00 to 01-SEP-11 01:39:00 (CST-6)
Location: AUBURN
Magnitude: 56.00 EG
Reported by: NWS Storm Survey

Several large tree branches and tree limbs were snapped off in shelterbelts along U. S. Highway 81.

Thunderstorm Wind in PEMBINA, NORTH DAKOTA
From 01-SEP-11 01:40:00 to 01-SEP-11 01:40:00 (CST-6)
Location: ST THOMAS ARPT
Magnitude: 56.00 EG
Reported by: NWS Storm Survey

Several large tree branches were broken down in shelterbelts along North Dakota highway 66.

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:42:00 to 01-SEP-11 01:42:00 (CST-6)
Location: GRAFTON
Magnitude: 78.00 EG
Reported by: Emergency Manager

Extensive damage occurred in Grafton. More than 50 large trees were blown down, including some 60 to 70 foot tall evergreens. Five houses and multiple vehicles were damaged by falling trees. One trailer house had substantial damage from a tree falling on it. The elevator in town was damaged, commercial buildings had metal siding blown off, and five or six utility poles were blown down. Several speed limit signs were bent over. Peak winds were estimated at 90 mph.

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:44:00 to 01-SEP-11 01:44:00 (CST-6)
Location: GRAFTON ARPT
Magnitude: 56.00 MG
Reported by: AWOS

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:39:00 to 01-SEP-11 01:39:00 (CST-6)
Location: AUBURN
Magnitude: 56.00 EG
Reported by: NWS Storm Survey

Several large tree branches and tree limbs were snapped off in shelterbelts along U. S. Highway 81.

Thunderstorm Wind in WALSH, NORTH DAKOTA
From 01-SEP-11 01:53:00 to 01-SEP-11 01:53:00 (CST-6)
Location: HERRICK
Magnitude: 78.00 EG
Reported by: Emergency Manager

Several large cottonwood trees and evergreens were snapped or uprooted in a farmyard. A metal flag pole was bent and shingles were tossed about.