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Avalanche Forecast

Archived

Dec 15th, 2015–Dec 16th, 2015

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

Regions

Olympics.

Pay extra attention if you see winds transporting snow and find more than a few inches of snowfall on Tuesday.

Detailed Forecast

A weak cold front will cross the Northwest on Tuesday. This should bring northwest winds and light snow to Hurricane Ridge with a brief, slight rise in the low snow levels.

New small shallow areas of wind and storm slab are possible at Hurricane. Wind slab might be found on more south aspects due to northwest winds. Pay extra attention if you see winds transporting snow and find more than a few inches of snowfall.

Previous wind slab layers from strong winds Saturday should further slightly stabilize but could still be triggered on previous lee slopes.

Snowpack Discussion

An atmospheric river and warm very wet weather was seen last week. This caused consolidation and stabilizing of the older part of the Olympics snowpack with the Waterhole snowdepth dropping to around 18 inches.

A stormy pattern with cooling was seen late last week and over the weekend with about 2.5 feet of snowfall at Hurricane.

A Park Ranger at Hurricane Ridge Sunday midday reported a storm slab release below the Sunrise Ridge likely on an east facing slope near Hurricane. The slide was likely triggered but this was not confirmed.  The avalanche crown was estimated at 2-3 feet and released about 150 wide and ran about 100 feet vertical - big enough to get into serious trouble.

A dry, cool day at Hurricane on Monday will have brought some stabilizing.

Terrain anchors have been somewhat buried by recent snowfall but will still add significant anchoring below about 4000-4500 feet.  

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). 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.