During the early evening of September 1st, a line of thunderstorms formed between Stump Lake, in Nelson County, and Pembina, in Cavalier County. However, one cell on the far southern end of the line quickly became the strongest storm, and it would hold together as the storm tracked to the south-southeast, through Griggs, Steele, and Cass counties, before weakening. This cell produced several weak tornadoes, funnel clouds, and large hail.

Tornado in NELSON, NORTH DAKOTA
From 01-SEP-17 16:30:00 to 01-SEP-17 16:31:00 (CST-6)
Location: TOLNA
Tornado F-scale: EF0
Reported by: Trained Spotter

A brief tornado touchdown with water swirl was noted over the north end of Stump Lake. As the tornado lifted, the funnel continued to track to the east. Peak winds were estimated at 70 mph.

Tornado in NELSON, NORTH DAKOTA
From 01-SEP-17 16:38:00 to 01-SEP-17 16:54:00 (CST-6)
Location: TOLNA
Tornado F-scale: EF0
Reported by: Trained Spotter

This tornado touched down just east of Stump Lake and tracked to the east. Photos showed a persistent rope tornado with intermittent dust swirls. Peak winds were estimated at 80 mph.

Funnel Cloud in GRIGGS, NORTH DAKOTA
From 01-SEP-17 18:15:00 to 01-SEP-17 18:15:00 (CST-6)
Location: COOPERSTOWN
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A funnel cloud was observed just west of the Steele County line in far southeast Romness Township.

Hail in STEELE, NORTH DAKOTA
From 01-SEP-17 18:25:00 to 01-SEP-17 18:25:00 (CST-6)
Location: FINLEY
Magnitude: 1.75 
Reported by: Public

Large hail fell with very heavy rain. Some of the hailstones were the size of golf balls.

Thunderstorm Wind in STEELE, NORTH DAKOTA
From 01-SEP-17 18:30:00 to 01-SEP-17 18:30:00 (CST-6)
Location: PICKERT
Magnitude: 56.00 EG
Reported by: Trained Spotter

Several four to eight inch diameter tree branches were snapped in a farmstead shelterbelt near county road 25, north of highway 200, in west central Greenview Township.

Thunderstorm Wind in STEELE, NORTH DAKOTA
From 01-SEP-17 18:50:00 to 01-SEP-17 18:50:00 (CST-6)
Location: HOPE
Magnitude: 52.00 EG
Reported by: Trained Spotter

Strong wind gusts were associated with the rear flank shelf cloud. Some dime to nickel sized hail fell as well.

Thunderstorm Wind in STEELE, NORTH DAKOTA
From 01-SEP-17 18:55:00 to 01-SEP-17 18:55:00 (CST-6)
Location: HOPE
Magnitude: 52.00 EG
Reported by: NWS Storm Survey

Large tree branches were blown down around the town of Hope. One poplar tree was snapped at the golf course.

Funnel Cloud in STEELE, NORTH DAKOTA
From 01-SEP-17 19:01:00 to 01-SEP-17 19:01:00 (CST-6)
Location: HOPE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A persistent wall cloud with a brief funnel cloud were observed. The wall cloud was nearly rain wrapped.

Hail in NELSON, NORTH DAKOTA
From 01-SEP-17 16:59:00 to 01-SEP-17 16:59:00 (CST-6)
Location: MC VILLE ARPT
Magnitude: 1.00 
Reported by: Public

Heavy rain was reported with a few dime to quarter sized hail.

Hail in NELSON, NORTH DAKOTA
From 01-SEP-17 17:25:00 to 01-SEP-17 17:25:00 (CST-6)
Location: KLOTEN
Magnitude: 1.25 
Reported by: Public

A few half dollar sized hailstones fell just north of highway 15, in northwest Lee Township.

Hail in GRIGGS, NORTH DAKOTA
From 01-SEP-17 17:56:00 to 01-SEP-17 17:56:00 (CST-6)
Location: JESSIE
Magnitude: 1.50 
Reported by: Public

Occasional nickel to ping pong ball sized hail fell in very heavy rain across southeast Lenora Township.

Thunderstorm Wind in CASS, NORTH DAKOTA
From 01-SEP-17 19:15:00 to 01-SEP-17 19:15:00 (CST-6)
Location: WALDEN
Magnitude: 52.00 EG
Reported by: NWS Storm Survey

A few large tree branches were blown down in shelterbelts. Corn and bean fields were flattened in spots across northwest Rochester and northeast Ellsbury townships.

Tornado in GRIGGS, NORTH DAKOTA
From 01-SEP-17 18:16:00 to 01-SEP-17 18:22:00 (CST-6)
Location: COOPERSTOWN
Tornado F-scale: EF0
Property damage: 1.00K
Crop damage: 2.00K
Reported by: NWS Storm Survey

This tornado tracked intermittently for about two miles across a portion of the Sheyenne River Valley. Large tree branches were broken down in various shelterbelts and groves along the path, mainly along the valley edge. Peak winds were estimated at 75 mph.