A large and slow moving Pacific low pressure system with abundant moisture moved across the central Rocky Mountain region.

Winter Weather in UPPER YAMPA RIVER BASIN, COLORADO
From 11-MAY-11 03:00:00 to 11-MAY-11 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 3 to 7 inches were measured at locations covering at least half of the area.  Locally higher amounts included 12 inches at Oak Creek.

Winter Weather in ELKHEAD AND PARK MOUNTAINS, COLORADO
From 10-MAY-11 23:00:00 to 12-MAY-11 01:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 5 to 12 inches were measured across the area.

Winter Storm in SOUTHWESTERN SAN JUAN MOUNTAINS, COLORADO
From 10-MAY-11 20:00:00 to 12-MAY-11 08:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Snowfall accumulations of 10 to 20 inches were measured across the area.  Wind gusts of 25 to 60 mph produced areas of blowing and drifting snow.

Heavy Snow in UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE, COLORADO
From 11-MAY-11 03:00:00 to 11-MAY-11 23:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 6 to 13 inches were measured across the area above the 7500 foot level, with elevations above the 8500 foot level having received around a foot of snow.

Heavy Snow in GORE AND ELK MOUNTAINS/CENTRAL MOUNTAIN VALLEYS, COLORADO
From 10-MAY-11 22:00:00 to 12-MAY-11 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 1 to 2 feet were measured across the area.

Winter Storm in NORTHWESTERN SAN JUAN MOUNTAINS, COLORADO
From 10-MAY-11 20:00:00 to 12-MAY-11 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Snowfall accumulations of 12 to 22 inches were measured across the area.  Wind gusts ranged from 25 to 50 mph and produced areas of blowing and drifting snow.  The heavy snow accumulations resulted in many avalanches, several of which came down across Highway 550 between the Monument and Red Mountain Pass.

Heavy Snow in WEST ELK AND SAWATCH MOUNTAINS, COLORADO
From 10-MAY-11 22:00:00 to 12-MAY-11 05:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Snowfall accumulations of 10 to 18 inches were measured across the area.

Heavy Snow in GRAND AND BATTLEMENT MESAS, COLORADO
From 10-MAY-11 23:00:00 to 12-MAY-11 05:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 11 to 14 inches were measured across the area.

Heavy Snow in PARADOX VALLEY / LOWER DOLORES RIVER BASIN, COLORADO
From 11-MAY-11 03:00:00 to 11-MAY-11 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snowfall accumulations of 3 to 7 inches were measured from locations covering about half of the area.

Avalanche in NORTHWESTERN SAN JUAN MOUNTAINS, COLORADO
From 12-MAY-11 05:00:00 to 12-MAY-11 10:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A number of avalanches occurred towards the end of the winter storm as a result of heavy snowfall accumulations and snow loading due to blowing and drifting snow.  Four avalanches came down across Highway 550 between the Monument and Red Mountain Pass.  The avalanches covered the road up to 4 feet deep in places.

Heavy Snow in FLATTOP MOUNTAINS, COLORADO
From 10-MAY-11 22:00:00 to 12-MAY-11 04:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Snowfall accumulations of 12 to 18 inches were measured across the area.