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Avalanche Forecast

Archived

Dec 27th, 2013–Dec 28th, 2013

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Olympics.

Detailed Forecast

Decreasing winds, decreasing clouds and mostly sunny weather should be seen Saturday. Warmer temperatures should be seen by Saturday afternoon.

The main concern should be any small shallow new wind slab built on lee slopes in the alpine and perhaps in the near treeline by the front on Friday.

Minor wet loose avalanches might also be possible by Saturday afternoon on solar aspects.

Shallow amounts of stable snow that generally bond well to previous snow should be seen on most other slopes but again only in the alpine or near treeline. 

Snowpack Discussion

The last significant snow at Hurricane occurred in early December. Either strong high pressure or systems with high freezing levels have limited the snow accumulations in the Olympics and specifically at Hurricane Ridge where the total snowdepth remains a meager 13 inches. The NWAC weather station at Hurricane has recorded less than 2 inches of water through December. 

The overall shallow snowpack has been limiting the avalanche danger, especially near tree line and below tree line where significant terrain and vegetative anchors remain. Field observations at Klahhane Ridge Sunday indicated the lack of snow on most slopes. On north facing slopes below the ridge there was evidence of old wind slab which was not reactive in tests. Rain to high elevations and lack of recent snow is maintaining mostly stable conditions with surface crusts or shallow wind drifts over crust layers.

A front is crossing the Northwest on Friday. This will cause southwest winds to shift to the northwest with rain changing to a little snow at the higher elevations in the Olympics with cooling temperatures.

 

View looking east along Klahhane Ridge, Olympics 12-22-2013, K. Reid

Problems

Wind Slabs

Wind Slab avalanches are the 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.