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Archived

Avalanche Forecast

Feb 4th, 2018–Feb 5th, 2018
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
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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

Regions: Mt Hood.

Slowly lowering freezing levels and light amounts of new snowfall will decrease the avalanche danger Monday in the Mt. Hood area. The upper snowpack will begin refreezing Monday, but loose wet avalanches are possible to trigger on steep slopes with wet surface snow, especially in the morning. Avoid slopes where avalanches may carry you into terrain traps.

Detailed Forecast

Slowly lowering freezing levels and light amounts of new snowfall will decrease the avalanche danger Monday in the Mt. Hood area. The wet upper snowpack will begin refreezing Monday, but loose wet avalanches are possible to trigger on steep slopes with wet surface snow, especially in the morning. Avoid slopes where avalanches may carry you into dangerous terrain such as over a cliff, into a creek, or down a gully. 

The likelihood for large and destructive wet slab avalanches originating from above treeline should decrease substantially Monday. However, limit your exposure to avalanche paths that originate at higher elevations for one more day to mitigate this low likelihood/high consequence problem.

Snowpack Discussion

Moderate to strong W-NW winds were seen over the weekend at Mt. Hood, but due to continued mild conditions, there is no snow available for transport in the above treeline band (NWAC's forecast does not apply above 7000-8000 feet). The recent mild and at times wet weather has created wet surface snow conditions well into the above treeline terrain in the Mt Hood area. 

The upper snowpack consist of a mix of wet snow, old crusts, and well consolidated storm snow. 

Observations

Mt. Hood Meadows pro-patrol reported that Friday's widespread wet loose avalanche activity had become more stubborn and isolated near and below treeline by Saturday.  The wet upper snowpack was still quite unconsolidated with the most recent 1/18 crust breaking down due to the sustained mild wet weather. Winds were strong near and above treeline but no snow was available for transport in area. 

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.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 1