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Archived

Avalanche Forecast

Dec 6th, 2015–Dec 7th, 2015
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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

Regions: Olympics.

Monday should become a wet day at Hurricane. Careful snow evaluation and cautious route finding should be essential if you venture into the alpine.

Detailed Forecast

A warm front on Sunday night will be rapidly followed by another warm front on Monday. Strong southwest to west winds should be seen in the alpine with moderate to heavy rain or snow Sunday night and by Monday midday with further warming. Snowfall so far in December by Monday morning at Hurricane will probably be about 1. 5 feet.

New wind and storm slab will be the focus on Monday at Hurricane Ridge where snow should change to rain. Careful snow evaluation and cautious route finding should be essential if you venture into the alpine.

With little snow near and especially below treeline at Hurricane, wet loose snow avalanches will not be in the forecast. But change your plans if you find wet snow deeper than a few inches or see signs of wet loose activity such as pin wheels or natural wet loose avalanches.

Snowpack Discussion

We have not received any snowpack observations from Hurricane Ridge so far this season, but given the warmer temperature regime over the Olympic Mountains lately, we don't expect any persistent weak layers problems like those seen in the Washington Cascades.

Avalanche Problems

Wind Slabs

Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

 

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

 

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

 

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 1

Storm Slabs

Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

 

You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.

 

Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 1