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Archived

Avalanche Forecast

Dec 30th, 2013–Dec 31st, 2013
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
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

Regions: Olympics.

Detailed Forecast

A weak frontal system should spread light rain and snow over the area tonight along with gradually lowering snow levels overnight. Light precipitation should taper off Tuesday afternoon.   

Generally light precipitation and a cooling trend should not greatly increase the avalanche danger on Tuesday.  However, precipitation amounts with this pattern have been poorly handled, so watch for shallow wind and storm slabs mainly in the near and above treeline zones. Moderately strong W to NW winds in the alpine overnight may develop new wind slab on lee N thru SE aspects. 

Snowpack Discussion

Very little recent snow and an overall very shallow snowpack are limiting the avalanche potential on most terrain, at least in the Hurricane Ridge area of the Olympics. Recent weather has been a mix of dry warm and sunny weather with periodic weak frontal passages depositing light amounts of new snow and/or rain. 

In the Hurricane Ridge area the only slopes with sufficient snow cover to create an avalanche potential are on steep shaded northerly facing slopes near or above treeline. In those areas, the snowpack mostly consists of firm surface or near surface crusts with possible shallow recent wind deposits.  Slopes exposed to either wind or sun have little to no snow to just above treeline.

Light rain and warm temperatures on Monday may have caused shallow loose wet slides at higher elevations that had available loose surface snow. 

There has been no recent avalanche activity reported in the Olympics.  

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, Treeline.

Likelihood: Possible

Expected Size: 1 - 1