A very unstable air mass, a potent low pressure trough, and supporting deep-layer shear combined to develop numerous severe thunderstorms.

Flash Flood in VALLEY, MONTANA
From 22-JUL-11 14:03:00 to 22-JUL-11 14:03:00 (MST-7)
Location: GLASGOW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Downtown BNSF underpass was flooded.  City storm drains were unable to handle the high volume of water flow.

Flash Flood in VALLEY, MONTANA
From 22-JUL-11 14:26:00 to 22-JUL-11 14:26:00 (MST-7)
Location: GLASGOW
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Standing water at a depth of one foot on US highway 2 in Glasgow.

Flash Flood in ROOSEVELT, MONTANA
From 22-JUL-11 15:45:00 to 22-JUL-11 15:45:00 (MST-7)
Location: POPLAR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Water depth up to 3 inches on city roads.

Flash Flood in MCCONE, MONTANA
From 22-JUL-11 17:00:00 to 22-JUL-11 17:00:00 (MST-7)
Location: VIDA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Water reported covering Mendenhall Road southwest of Wolf Point.

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:03:00 to 22-JUL-11 12:03:00 (MST-7)
Location: CONTENT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in VALLEY, MONTANA
From 22-JUL-11 13:43:00 to 22-JUL-11 13:43:00 (MST-7)
Location: GLASGOW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, MONTANA
From 22-JUL-11 13:46:00 to 22-JUL-11 13:46:00 (MST-7)
Location: GLASGOW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Quarter-sized hail stones fell at the Glasgow NWS Forecast Office.

Hail in VALLEY, MONTANA
From 22-JUL-11 13:59:00 to 22-JUL-11 13:59:00 (MST-7)
Location: DUCK CREEK
Magnitude: 2.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, MONTANA
From 22-JUL-11 14:04:00 to 22-JUL-11 14:04:00 (MST-7)
Location: NASHUA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in VALLEY, MONTANA
From 22-JUL-11 14:45:00 to 22-JUL-11 14:45:00 (MST-7)
Location: FRAZER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in MCCONE, MONTANA
From 22-JUL-11 14:46:00 to 22-JUL-11 14:46:00 (MST-7)
Location: BROCKWAY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, MONTANA
From 22-JUL-11 14:46:00 to 22-JUL-11 14:46:00 (MST-7)
Location: FRAZER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in VALLEY, MONTANA
From 22-JUL-11 14:46:00 to 22-JUL-11 14:46:00 (MST-7)
Location: LUSTRE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, MONTANA
From 22-JUL-11 15:00:00 to 22-JUL-11 15:00:00 (MST-7)
Location: NASHUA
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail still visible on the ground 4 hours after the event.  Some crop damage noted.

Hail in PRAIRIE, MONTANA
From 22-JUL-11 15:20:00 to 22-JUL-11 15:20:00 (MST-7)
Location: MC CLOUD
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Rain in VALLEY, MONTANA
From 22-JUL-11 14:05:00 to 22-JUL-11 14:05:00 (MST-7)
Location: GLASGOW
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Measured 1.55 inches of rain which fell in 25 minutes at the NWS Forecast Office in Glasgow.

Heavy Rain in VALLEY, MONTANA
From 22-JUL-11 14:15:00 to 22-JUL-11 14:15:00 (MST-7)
Location: GLASGOW
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Measured 2.12 inches of rain in less than one hour.

Thunderstorm Wind in VALLEY, MONTANA
From 22-JUL-11 14:30:00 to 22-JUL-11 14:30:00 (MST-7)
Location: DUCK CREEK
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Roof was damaged by high winds.

Thunderstorm Wind in MCCONE, MONTANA
From 22-JUL-11 14:46:00 to 22-JUL-11 14:46:00 (MST-7)
Location: BROCKWAY
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MCCONE, MONTANA
From 22-JUL-11 15:15:00 to 22-JUL-11 15:15:00 (MST-7)
Location: VIDA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement official estimated wind speeds around 60 mph.

Thunderstorm Wind in DAWSON, MONTANA
From 22-JUL-11 16:00:00 to 22-JUL-11 16:00:00 (MST-7)
Location: RICHEY
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter also measured 1.78 inches of rain.

Thunderstorm Wind in PRAIRIE, MONTANA
From 22-JUL-11 16:11:00 to 22-JUL-11 16:11:00 (MST-7)
Location: TERRY
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in DAWSON, MONTANA
From 22-JUL-11 16:12:00 to 22-JUL-11 16:12:00 (MST-7)
Location: GLENDIVE
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in DAWSON, MONTANA
From 22-JUL-11 16:12:00 to 22-JUL-11 16:12:00 (MST-7)
Location: BLOOMFIELD
Magnitude: 65.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DAWSON, MONTANA
From 22-JUL-11 16:55:00 to 22-JUL-11 16:55:00 (MST-7)
Location: GLENDIVE
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in WIBAUX, MONTANA
From 22-JUL-11 17:26:00 to 22-JUL-11 17:26:00 (MST-7)
Location: WIBAUX
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported an estimated 75 mph wind speed.

Thunderstorm Wind in WIBAUX, MONTANA
From 22-JUL-11 17:30:00 to 22-JUL-11 17:30:00 (MST-7)
Location: WIBAUX
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Trees knocked over from estimated 75 mph wind gusts.

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:00:00 to 22-JUL-11 12:00:00 (MST-7)
Location: MALTA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:00:00 to 22-JUL-11 12:00:00 (MST-7)
Location: MALTA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:03:00 to 22-JUL-11 12:03:00 (MST-7)
Location: MALTA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:03:00 to 22-JUL-11 12:03:00 (MST-7)
Location: MALTA
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:10:00 to 22-JUL-11 12:10:00 (MST-7)
Location: MALTA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:10:00 to 22-JUL-11 12:10:00 (MST-7)
Location: MALTA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:10:00 to 22-JUL-11 12:10:00 (MST-7)
Location: MALTA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:15:00 to 22-JUL-11 12:15:00 (MST-7)
Location: MALTA
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SHAVE Project

Hail in VALLEY, MONTANA
From 22-JUL-11 14:00:00 to 22-JUL-11 14:10:00 (MST-7)
Location: DUCK CREEK
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail lasted for 10 minutes, and totally covered the ground.  Also, a 1/2 of rain fell.

Hail in MCCONE, MONTANA
From 22-JUL-11 14:10:00 to 22-JUL-11 14:15:00 (MST-7)
Location: FT PECK LAKE HANDAR
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in PHILLIPS, MONTANA
From 22-JUL-11 12:15:00 to 22-JUL-11 12:15:00 (MST-7)
Location: MALTA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MCCONE, MONTANA
From 22-JUL-11 15:46:00 to 22-JUL-11 15:46:00 (MST-7)
Location: BROCKWAY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DAWSON, MONTANA
From 22-JUL-11 16:40:00 to 22-JUL-11 16:40:00 (MST-7)
Location: GLENDIVE
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Lots of damage to trees and branches in the area.  Also received a quarter inch of rain.

Thunderstorm Wind in VALLEY, MONTANA
From 22-JUL-11 13:38:00 to 22-JUL-11 13:45:00 (MST-7)
Location: GLASGOW
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm winds moved several round hay bales over 100 yards, part of the way being uphill.  Baseball size hail also fell.

Thunderstorm Wind in PRAIRIE, MONTANA
From 22-JUL-11 16:12:00 to 22-JUL-11 16:12:00 (MST-7)
Location: TERRY
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A semi-truck at mile marker 157 on the interstate was blown over.  The trailer was empty. DES confirmed it was straight line winds.

Hail in VALLEY, MONTANA
From 22-JUL-11 13:42:00 to 22-JUL-11 13:42:00 (MST-7)
Location: GLASGOW
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Mainly dime-sized to quarter-sized hail stones fell at the Glasgow NWS Forecast Office mixed with some half-dollar-sized stones.

Hail in VALLEY, MONTANA
From 22-JUL-11 14:05:00 to 22-JUL-11 14:05:00 (MST-7)
Location: NASHUA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in VALLEY, MONTANA
From 22-JUL-11 13:38:00 to 22-JUL-11 13:45:00 (MST-7)
Location: GLASGOW
Magnitude: 2.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Baseball size hail shattered windows on the north and west sides of homes and buildings.