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Archived

Avalanche Forecast

Dec 15th, 2018–Dec 16th, 2018
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
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: Olympics.

Early season conditions exist in the Hurricane Ridge area with large variations in snow cover. Avoid terrain where even a small avalanche could cause injury paired with terrain traps like exposed rocks and vegetation. 

Discussion

Discussion 

Low snow conditions continue to limit the overall avalanche hazard in the Olympics. Snow cover varies widely by elevation and especially aspect.

On windward southerly facing terrain, much of the area is void of snow cover. While on shaded and wind loaded north to east facing terrain the snow-depths averaged about 4 feet as of Thursday afternoon.

Older wind slabs may linger on lee aspects above treeline, but should be stubborn and unlikely to trigger given the lack of recent snow and warm temperatures. 

Forecast schedule

For the 2018-19 winter season, avalanche hazard ratings will be issued for the Olympics Friday through Sunday and during holidays.

On days that the Hurricane Ridge road is closed, No Rating will be applied. We will continue to provide general snowpack and weather summaries for the Hurricane Ridge area even when No Rating is issued. 

Snowpack Discussion

We made it through our first strong winter storm and are headed into a weekend with dangerous and fickle avalanche conditions. Thick slabs of new snow (2-5 feet) are perched above a weak layer of faceted crystals. Avalanches triggered on this layer could be very large and life-threatening.

Reports continue to come in of very large natural and explosives triggered avalanches in the northern and eastern zones. For perspective, several of these slides have been classified as D3, or large enough to destroy a house.

Anyone accessing alpine areas should limit their exposure to areas where avalanches start, run and stop. In some places, the weak snow will talk to you by whumpfing and cracking. In other places, the heavy blanket of new snow is thick enough that it can give a false sense of stability while it masks the dangerous layering below.

Approximate snow totals from 12/10 - 12/14:  

  • Mt. Baker: 55”

  • Washington Pass: 29”

  • Stevens Pass: 37”

  • Snoqualmie Pass: 28”

  • Paradise: 38”

  • Mt. Hood Meadows: 13”

  • Olympics: mostly rain

The change in the snowpack is pretty dramatic with elevation. The height of snow decreases rapidly below 4500’ at Baker and Washington Pass, 5500’ at Crystal/Rainier. The Passes have better low elevation coverage, but it's still pretty thin below 4000’. With additional warm storms in the forecast, this pattern is expected to continue for a while.

Be cautious and get home safe.

Avalanche Problems

Loose Wet

Small loose wet avalanches will become likely in steep terrain due to rain falling on shallow amounts of new snow. Getting pushed by a small avalanche into exposed rocks, vegetation or other terrain traps poses the greatest hazard in the Hurricane Ridge area. 

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: Likely

Expected Size: 1 - 1