Severe thunderstorms moved from southeast Saskatchewan into northeast Montana, and then into northwest North Dakota where the environment was rich in low level moisture with enhanced deep and low level shear. Initially, supercell thunderstorms produced very large hail up to the size of tennis balls over Williams County before transitioning to a hail and wind threat with reported wind gusts around 62 mph as the storms approached McKenzie County. A mix of severe wind and hail occurred in McKenzie County before a tornado developed along a line of strong wind just to the west of a large recreational vehicle, camper, and mobile home park on the southwest side of Watford City. About 135 people were displaced from their homes. One fatality occurred and 28 people were injured, about 13 of them seriously. Based on the damage the tornado was rated EF2 and from that winds were estimated to have been around 127 mph. The tornado passed through the park causing extensive and severe damage to over 100 recreational vehicles, campers, and single wide manufactured homes. Power poles were snapped and other non-occupied buildings were damaged and some destroyed, including a well-built pole barn. Many vehicles were damaged, some totaled.

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 20:15:00 to 09-JUL-18 20:18:00 (CST-6)
Location: GRENORA
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 20:15:00 to 09-JUL-18 20:16:00 (CST-6)
Location: GRENORA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Funnel Cloud in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 21:15:00 to 09-JUL-18 21:17:00 (CST-6)
Location: (ISN)SLOULIN FLD WIL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 21:25:00 to 09-JUL-18 21:28:00 (CST-6)
Location: (ISN)SLOULIN FLD WIL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 21:38:00 to 09-JUL-18 21:41:00 (CST-6)
Location: SPRING BROOK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 21:40:00 to 09-JUL-18 21:47:00 (CST-6)
Location: BONETRAILL
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A window was broken on the north side of a house. That allowed wind and water into the home.

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 21:50:00 to 09-JUL-18 21:54:00 (CST-6)
Location: BONETRAILL
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 22:26:00 to 09-JUL-18 22:28:00 (CST-6)
Location: WILLISTON
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 22:30:00 to 09-JUL-18 22:32:00 (CST-6)
Location: (ISN)SLOULIN FLD WIL
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MCKENZIE, NORTH DAKOTA
From 09-JUL-18 22:30:00 to 09-JUL-18 22:33:00 (MST-7)
Location: ALEXANDER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 22:31:00 to 09-JUL-18 22:34:00 (CST-6)
Location: (ISN)SLOULIN FLD WIL
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in MCKENZIE, NORTH DAKOTA
From 09-JUL-18 22:34:00 to 09-JUL-18 22:36:00 (MST-7)
Location: ARNEGARD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law Enforcement estimated 60 mph thunderstorm wind gusts.

Hail in WILLIAMS, NORTH DAKOTA
From 09-JUL-18 22:48:00 to 09-JUL-18 22:51:00 (CST-6)
Location: WILLISTON
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in MCKENZIE, NORTH DAKOTA
From 09-JUL-18 22:55:00 to 09-JUL-18 22:58:00 (MST-7)
Location: WATFORD CITY
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm Wind in MCLEAN, NORTH DAKOTA
From 10-JUL-18 01:43:00 to 10-JUL-18 01:46:00 (CST-6)
Location: GARRISON
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Tornado in MCKENZIE, NORTH DAKOTA
From 09-JUL-18 22:45:00 to 09-JUL-18 22:48:00 (MST-7)
Location: WATFORD CITY
Tornado F-scale: EF2
Property damage: 3.50M
Crop damage: 0.00K
Reported by: NWS Storm Survey

About 135 people were displaced from their homes. One fatality occurred and 28 people were injured, about 13 of them seriously. Based on the damage the tornado was rated EF2 and from that winds were estimated to have been around 127 mph.
This tornado developed just to the west of a large recreational vehicle, camper, and mobile home park on the southwest side of Watford City. The tornado passed through the park causing extensive and severe damage to over 100 recreational vehicles, campers, and single wide manufactured homes. Power poles were snapped and other non-occupied buildings were damaged and some destroyed, including a well-built pole barn. Many vehicles were damaged, some totaled.