Discrete storms developed initially ahead of a strong shortwave in moderate instability and shear. The initial storms produced large hail and several funnel clouds along with three short-lived tornadoes, one in Morton County, one in Stark, and one in Dunn County. There was no damage with the three tornadoes and so they were all rated EF0. Additional storm growth then occurred, forming into a small mesoscale convective system with large hail and strong wind gusts as the main threats. The largest hail was half-dollar size, and fell in both Hettinger and Dunn Counties. The strongest wind gusts of 75 mph occurred in Morton and Rolette counties.

Hail in DUNN, NORTH DAKOTA
From 31-MAY-18 13:00:00 to 31-MAY-18 13:03:00 (MST-7)
Location: MARSHALL
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: COOP Observer

Windows were broken by the hail.

Hail in STARK, NORTH DAKOTA
From 31-MAY-18 13:30:00 to 31-MAY-18 13:33:00 (MST-7)
Location: DICKINSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in STARK, NORTH DAKOTA
From 31-MAY-18 14:15:00 to 31-MAY-18 14:18:00 (MST-7)
Location: DICKINSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HETTINGER, NORTH DAKOTA
From 31-MAY-18 15:20:00 to 31-MAY-18 15:30:00 (MST-7)
Location: NEW ENGLAND
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm Wind in HETTINGER, NORTH DAKOTA
From 31-MAY-18 15:30:00 to 31-MAY-18 15:35:00 (MST-7)
Location: MOTT
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Public

A wind break was torn down and a roof was damaged.

Thunderstorm Wind in STARK, NORTH DAKOTA
From 31-MAY-18 16:06:00 to 31-MAY-18 16:10:00 (MST-7)
Location: LEFOR
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement estimated a thunderstorm wind gust of 60 mph.

Thunderstorm Wind in MORTON, NORTH DAKOTA
From 31-MAY-18 17:15:00 to 31-MAY-18 17:19:00 (CST-6)
Location: GLEN ULLIN
Magnitude: 65.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Hail in GRANT, NORTH DAKOTA
From 31-MAY-18 18:15:00 to 31-MAY-18 18:18:00 (MST-7)
Location: CARSON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Funnel Cloud in GRANT, NORTH DAKOTA
From 31-MAY-18 18:19:00 to 31-MAY-18 18:22:00 (MST-7)
Location: CARSON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A deputy sheriff located in Carson observed the funnel cloud and estimated it to be about three miles east of Carson.

Hail in HETTINGER, NORTH DAKOTA
From 31-MAY-18 18:29:00 to 31-MAY-18 18:32:00 (MST-7)
Location: MOTT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in HETTINGER, NORTH DAKOTA
From 31-MAY-18 18:31:00 to 31-MAY-18 18:34:00 (MST-7)
Location: MOTT
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in HETTINGER, NORTH DAKOTA
From 31-MAY-18 18:35:00 to 31-MAY-18 18:40:00 (MST-7)
Location: MOTT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MORTON, NORTH DAKOTA
From 31-MAY-18 19:36:00 to 31-MAY-18 19:39:00 (CST-6)
Location: FLASHER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public estimated a thunderstorm wind gust of 60 mph.

Hail in SIOUX, NORTH DAKOTA
From 31-MAY-18 21:20:00 to 31-MAY-18 21:23:00 (MST-7)
Location: SELFRIDGE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tornado in STARK, NORTH DAKOTA
From 31-MAY-18 15:19:00 to 31-MAY-18 15:24:00 (MST-7)
Location: RICHARDTON
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

The tornado occurred over rural locations south of Richardton. No damage occurred, therefore the tornado was rated EF0.

Thunderstorm Wind in DUNN, NORTH DAKOTA
From 31-MAY-18 13:00:00 to 31-MAY-18 13:03:00 (MST-7)
Location: MARSHALL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A COOP Observer estimated a thunderstorm wind gust of 60 mph.

Hail in GRANT, NORTH DAKOTA
From 31-MAY-18 19:09:00 to 31-MAY-18 19:12:00 (MST-7)
Location: NEW LEIPZIG
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Tornado in DUNN, NORTH DAKOTA
From 31-MAY-18 12:43:00 to 31-MAY-18 12:46:00 (MST-7)
Location: EMERSON
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

The tornado occurred over rural locations northwest of Hirschville. No damage occurred, therefore the tornado was rated EF0.

Tornado in MORTON, NORTH DAKOTA
From 31-MAY-18 17:15:00 to 31-MAY-18 17:17:00 (CST-6)
Location: GLEN ULLIN
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

The tornado occurred over rural locations north of Glen Ullin. No damage occurred, therefore the tornado was rated EF0.

Thunderstorm Wind in ROLETTE, NORTH DAKOTA
From 31-MAY-18 16:13:00 to 31-MAY-18 16:17:00 (CST-6)
Location: BELCOURT
Magnitude: 65.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

One semi-trailer was blown over and a spruce tree was uprooted.  Some tin from a pole barn style building also blew off.