Warm, moist air from the southeast interacted with a low pressure system from the Pacific Northwest to generate multiple strong and severe thunderstorms which were focused mainly near the system's cold front as it passed through northeast Montana.

Thunderstorm Wind in GARFIELD, MONTANA
From 21-MAY-16 16:49:00 to 21-MAY-16 16:49:00 (MST-7)
Location: JORDAN
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Jordan Airport ASOS site recorded 64 mph wind gusts.

Hail in PHILLIPS, MONTANA
From 21-MAY-16 17:15:00 to 21-MAY-16 17:15:00 (MST-7)
Location: SUN PRAIRIE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported mostly nickel and pea sized hail with some as large as quarters. Strong winds also reported.

Hail in PHILLIPS, MONTANA
From 21-MAY-16 17:22:00 to 21-MAY-16 17:22:00 (MST-7)
Location: HARB
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported mostly small hail mixed with a few ping pong ball sized hailstones.

Hail in GARFIELD, MONTANA
From 21-MAY-16 17:24:00 to 21-MAY-16 17:24:00 (MST-7)
Location: JORDAN AIRPORT (KJDN)
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported golf ball sized hail.

Thunderstorm Wind in GARFIELD, MONTANA
From 21-MAY-16 16:30:00 to 21-MAY-16 16:30:00 (MST-7)
Location: JORDAN
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported estimated 70-80 mph wind gusts.

Hail in GARFIELD, MONTANA
From 21-MAY-16 15:30:00 to 21-MAY-16 16:00:00 (MST-7)
Location: SAND SPGS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported quarter sized hail for this 30 minute period.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:35:00 to 21-MAY-16 17:35:00 (MST-7)
Location: HINSDALE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public estimated 60 mph wind gusts with heavy rain and visibility less than 50 feet.

Hail in VALLEY, MONTANA
From 21-MAY-16 17:35:00 to 21-MAY-16 17:35:00 (MST-7)
Location: HINSDALE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported quarter sized hail.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:35:00 to 21-MAY-16 17:35:00 (MST-7)
Location: HINSDALE
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported a tin roof torn off a building and tree branches downed.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:38:00 to 21-MAY-16 17:38:00 (MST-7)
Location: GLASGOW
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Glasgow Airport ASOS measured a 58 mph wind gust.

Hail in VALLEY, MONTANA
From 21-MAY-16 17:38:00 to 21-MAY-16 17:38:00 (MST-7)
Location: HINSDALE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported nickel sized hail.

Hail in VALLEY, MONTANA
From 21-MAY-16 17:45:00 to 21-MAY-16 17:45:00 (MST-7)
Location: HINSDALE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained Spotter reported half dollar sized hail.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:45:00 to 21-MAY-16 17:45:00 (MST-7)
Location: HINSDALE
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported a 20-foot section of roof blown off a shed.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:45:00 to 21-MAY-16 17:45:00 (MST-7)
Location: HINSDALE
Magnitude: 78.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter estimated wind gusts of 80-90 mph.

Hail in VALLEY, MONTANA
From 21-MAY-16 17:58:00 to 21-MAY-16 17:58:00 (MST-7)
Location: PARK GROVE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public estimated ping pong ball sized hail near the confluence of the Milk and Missouri Rivers.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 18:05:00 to 21-MAY-16 18:05:00 (MST-7)
Location: THOENY
Magnitude: 72.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Bluff Creek RAWS site measure an 83 mph wind gust.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 18:07:00 to 21-MAY-16 18:07:00 (MST-7)
Location: FRAZER
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An NWS employee reported wind gusts up to 65 mph.

Thunderstorm Wind in GARFIELD, MONTANA
From 21-MAY-16 18:10:00 to 21-MAY-16 18:10:00 (MST-7)
Location: COHAGEN
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 50 to 60 mph wind gusts.

Hail in GARFIELD, MONTANA
From 21-MAY-16 17:05:00 to 21-MAY-16 17:05:00 (MST-7)
Location: JORDAN AIRPORT (KJDN)
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported golf ball sized hail and windows broken out of the west side of a ranch home.

Hail in MCCONE, MONTANA
From 21-MAY-16 18:07:00 to 21-MAY-16 18:07:00 (MST-7)
Location: FT PECK LAKE HANDAR
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An NWS employee reported quarter sized hail near Signal Hill.

Thunderstorm Wind in GARFIELD, MONTANA
From 21-MAY-16 17:05:00 to 21-MAY-16 17:05:00 (MST-7)
Location: JORDAN AIRPORT (KJDN)
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported 70 mph wind gusts.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:38:00 to 21-MAY-16 17:38:00 (MST-7)
Location: HINSDALE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 60 mph wind gusts.

Thunderstorm Wind in VALLEY, MONTANA
From 21-MAY-16 17:30:00 to 21-MAY-16 17:30:00 (MST-7)
Location: GLASGOW INTL AIRPORT (KGGW)
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported a cedar wood swing set lifted up and tipped over by strong thunderstorm wind gusts.