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Archived

Avalanche Forecast

Feb 13th, 2015–Feb 14th, 2015
Alpine
1: Low
The avalanche danger rating in the alpine will be low
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Mt Hood.

It is a stretch to find a primary avalanche problem Saturday, but some sunshine later in the day, may make shallow wet snow avalanches possible. 

Detailed Forecast

A few showers early Saturday should give way to mostly cloudy conditions later Saturday and cooler temperatures. The cooler temperatures should limit melt and weakening of surface snow and may allow surface snow and form a crust at upper elevations. This should limit the potential for wet snow avalanches. 

Loose wet avalanches are unlikely Saturday due to the cooling, some some shallow wet snow may persist.    

As a result of the overall low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation.

Snowpack Discussion

The latest warm and moist southwesterly flow to impact the Pacific Northwest brought less rain to Mt. Hood compared to areas in the WA Cascades late last week. This led to further overall snowpack melt at lower elevations.   

The last frontal system crossed the south Cascades late Monday. This caused strong winds and heavy snow in the above treeline zone at Mt Hood.

A cooling storm Monday through early Tuesday deposited 15 inches of new snow at 6600 feet at Mt Hood Meadows. Avalanche control gave numerous size 1-2 wind and storm slab avalanches on lee slopes but with limited propagation. Similar wind slab concerns were reported on lee east aspects west of Timberline Tuesday on the NWAC observation page.  

These storm and wind slabs quickly stabilized under warming temperatures and sunshine and no other storm avalanches have been reported over the past few days. 

The mid and lower snowpack at Mt Hood should consist of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.

Avalanche Problems

Loose Wet

Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

 

Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.

 

Several loose wet avalanches, and lots of pinwheels and roller balls.

Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.

Elevations: Treeline, Below Treeline.

Likelihood: Unlikely

Expected Size: 1 - 1