An upper trough moved into the Western United States, helping to develop an intense surface low pressure system. This low moved into the northern Plains with intense wrap around cold air, wind and snow. The hardest hit areas were zones close to the North Dakota border.

High Wind in CENTRAL AND SOUTHERN VALLEY, MONTANA
From 30-APR-11 01:00:00 to 30-APR-11 17:08:00 (MST-7)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

At 1244 MST, King Coulee RAWS reported a measured wind gust of 58 mph, At 1506 MST, Nashua reported sustained winds over 45 mph with sustained winds over 40 mph since 1155 MST.

High Wind in GARFIELD, MONTANA
From 30-APR-11 02:00:00 to 30-APR-11 17:08:00 (MST-7)
Magnitude: 36.00 MS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Hillside DOT sensor had sustained winds of over 40 mph with peak gusts near 60 mph. The Jordan ASOS had sustained winds over 40 mph with frequent gusts over 50 mph.

Blizzard in SHERIDAN, MONTANA
From 30-APR-11 00:00:00 to 30-APR-11 13:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Plentywood reported sustained winds between 35 and 50 mph with a gust to 61 mph while the Crosby, ND RAWS reported a gust to 78 mph. Whiteout conditions were reported by Law Enforcement on Highway 5. Electricity was lost in Wesby with winds estimated to peak at 80 mph. This created drifts to 6 feet deep, uprooted a 300 foot tall pine tree (with a 15 to 20 inch diameter trunk) and rotated a stop sign.

High Wind in WESTERN ROOSEVELT, MONTANA
From 29-APR-11 23:00:00 to 30-APR-11 17:08:00 (MST-7)
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

McDonald's DOT sensor had sustained winds from 45 to 65 mph. The Wolf Point ASOS only reported winds between 35 to 50 mph.

Blizzard in WIBAUX, MONTANA
From 30-APR-11 00:00:00 to 30-APR-11 18:11:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Beaver Hill RAWS reported winds sustained above 40 mph with a gust to 64 mph. Blizzard conditions were reported by the Emergency Manager with trucks sliding off of I-94 and stuck in ditches on Highway 7 along with plows. 4 to 5 foot drifts were common. 12 inches of new snow were reported near Carlyle.

High Wind in PRAIRIE, MONTANA
From 30-APR-11 02:00:00 to 30-APR-11 17:07:00 (MST-7)
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winds at Fallon were sustained over 35 mph with a peak gust of 67 mph. A gust to 61 mph were reported at Big Sheep RAWS.

Blizzard in DAWSON, MONTANA
From 30-APR-11 01:00:00 to 30-APR-11 18:11:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

The Glendive AWOS reported several hours of sustained winds above 40 mph through 1600 MST with a gust to 67 mph. Lindsay Divide had similar winds with a gust to 59 mph. A small amount of snow fell too with the most being reported (2) at 2 miles west of Bloomfield. Blizzard conditions were reported over most of the county. Power was lost at 0235 MST in the Lindsay area.

Blizzard in RICHLAND, MONTANA
From 30-APR-11 03:00:00 to 30-APR-11 17:11:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winds were sustained at 35 to 45 mph with gusts to 60 mph for several hours. A peak gust of 75 mph was reported at the Sioux Pass DOT station. Snow amounts ranged from 2 to 8 inches, which contributed to the blizzard conditions. Power lines and trees were knocked down by the heavy/wet snow and damaging winds.

Blizzard in EASTERN ROOSEVELT, MONTANA
From 30-APR-11 00:00:00 to 30-APR-11 17:11:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Poplar RAWS reported sustained winds of 40 mph while the DOT sensor at the state line reported a gust to 75 mph before power was lost at 0430 MST April 30th. Visibility of only 10 feet and drifts of 3 to 4 feet helped cause vehicles from Bainville to the North Dakota state line get stuck or slide off of U.S. Highway 2. County Emergency Manager reported that the wind and snow combined knocked out power to an estimated 1500 customers in Eastern Roosevelt and Sheridan Counties. Also on April 30th, a box car from a freight train grabbed low hanging power lines and power poles and dragged them along, ripping up fences.

High Wind in DANIELS, MONTANA
From 29-APR-11 23:00:00 to 30-APR-11 17:08:00 (MST-7)
Magnitude: 39.00 MS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

At 0200 MST, Rockglen Saskatchewan reported several hours with winds sustained over 30 mph and frequent gusts over 45 mph. A Ham Radio operator/weather spotter had sustained winds in the 40s with gusts over 50 mph a few times from 0200 to 1400 MST.