A surface low deepened over southeastern Montana which led to moisture increasing over the Dakotas. Strong instability developed in conjunction with enhanced deep layer shear. Initial storms developed as a short wave slid into the area in the afternoon, with storms continuing well into the evening as a low level jet strengthened over the region.  One notable complex of supercell thunderstorms moved through southwest into far south central North Dakota in the evening producing a swath of damage from strong winds estimated as high as 95 mph. Electric Cooperatives in western North Dakota reported in excess of 60 poles damaged, along with transmission lines. Damage was around $1.5 million.

Hail in MCKENZIE, NORTH DAKOTA
From 20-JUL-17 13:50:00 to 20-JUL-17 13:52:00 (MST-7)
Location: RAWSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MCKENZIE, NORTH DAKOTA
From 20-JUL-17 13:54:00 to 20-JUL-17 13:56:00 (MST-7)
Location: RAWSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MCKENZIE, NORTH DAKOTA
From 20-JUL-17 14:19:00 to 20-JUL-17 14:22:00 (MST-7)
Location: WATFORD CITY
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MCKENZIE, NORTH DAKOTA
From 20-JUL-17 14:24:00 to 20-JUL-17 14:27:00 (MST-7)
Location: WATFORD CITY
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in SLOPE, NORTH DAKOTA
From 20-JUL-17 14:30:00 to 20-JUL-17 14:35:00 (MST-7)
Location: AMIDON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in SLOPE, NORTH DAKOTA
From 20-JUL-17 14:47:00 to 20-JUL-17 14:52:00 (MST-7)
Location: AMIDON
Magnitude: 80.00 EG
Property damage: 400.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A hopper style grain bin was destroyed at a ranch. Electrical poles in the area were snapped.

Hail in SLOPE, NORTH DAKOTA
From 20-JUL-17 15:05:00 to 20-JUL-17 15:09:00 (MST-7)
Location: AMIDON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DUNN, NORTH DAKOTA
From 20-JUL-17 15:23:00 to 20-JUL-17 15:32:00 (MST-7)
Location: HALLIDAY
Magnitude: 80.00 EG
Property damage: 275.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Multiple power poles were snapped in and around the community of Halliday.

Thunderstorm Wind in SLOPE, NORTH DAKOTA
From 20-JUL-17 15:26:00 to 20-JUL-17 15:32:00 (MST-7)
Location: AMIDON
Magnitude: 70.00 EG
Property damage: 90.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Two outbuildings on a farm were toppled. Windows on the home were broken.

Hail in STARK, NORTH DAKOTA
From 20-JUL-17 15:26:00 to 20-JUL-17 15:29:00 (MST-7)
Location: DICKINSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in SLOPE, NORTH DAKOTA
From 20-JUL-17 15:34:00 to 20-JUL-17 15:40:00 (MST-7)
Location: AMIDON
Magnitude: 70.00 EG
Property damage: 80.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A barn collapsed at a ranch, and animals were trapped inside.

Thunderstorm Wind in BOWMAN, NORTH DAKOTA
From 20-JUL-17 15:34:00 to 20-JUL-17 15:41:00 (MST-7)
Location: RHAME
Magnitude: 78.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A barn was destroyed with the debris completely removed from the original site.

Hail in DUNN, NORTH DAKOTA
From 20-JUL-17 15:34:00 to 20-JUL-17 15:39:00 (MST-7)
Location: HALLIDAY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in BOWMAN, NORTH DAKOTA
From 20-JUL-17 15:39:00 to 20-JUL-17 15:44:00 (MST-7)
Location: RHAME
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A motorcycle was knocked over and a flag was torn up.

Hail in STARK, NORTH DAKOTA
From 20-JUL-17 15:42:00 to 20-JUL-17 15:45:00 (MST-7)
Location: DICKINSON
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

Thunderstorm Wind in SLOPE, NORTH DAKOTA
From 20-JUL-17 16:07:00 to 20-JUL-17 16:12:00 (MST-7)
Location: AMIDON
Magnitude: 70.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Four grain grain bins were damaged by the thunderstorm winds.

Thunderstorm Wind in BOWMAN, NORTH DAKOTA
From 20-JUL-17 16:07:00 to 20-JUL-17 16:12:00 (MST-7)
Location: GRIFFIN
Magnitude: 80.00 EG
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Power lines were down near Griffin.

Thunderstorm Wind in BOWMAN, NORTH DAKOTA
From 20-JUL-17 16:20:00 to 20-JUL-17 16:24:00 (MST-7)
Location: BUFFALO SPGS
Magnitude: 63.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in ADAMS, NORTH DAKOTA
From 20-JUL-17 16:53:00 to 20-JUL-17 16:55:00 (MST-7)
Location: HETTINGER ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in GRANT, NORTH DAKOTA
From 20-JUL-17 17:30:00 to 20-JUL-17 17:33:00 (MST-7)
Location: NEW LEIPZIG
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated 60 mph thunderstorm wind gusts.

Thunderstorm Wind in GRANT, NORTH DAKOTA
From 20-JUL-17 17:35:00 to 20-JUL-17 17:42:00 (MST-7)
Location: ELGIN
Magnitude: 65.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Shingles were blown off about one-quarter of a roof on a home. Some plywood was also stripped from the roof. Multiple branches were down around the city of Elgin.