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Avalanche Forecast

Archived

Dec 28th, 2014–Dec 29th, 2014

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.

The avalanche danger should decrease but continue to evaluate snow and terrain carefully on Monday.  

Detailed Forecast

Light northeast winds, clouds giving way to some sun and cool temperatures should be seen in the Olympics on Monday.This should cause stabilizing and a decreasing avalanche danger on Monday.

Lingering wind slab will be rated as possible for the Olympics on Monday. Watch for firmer wind transported snow on steep lee slopes.

Lingering storm slab should be small and unlikely on Monday but watch for it in any areas that seem to have received heavier amounts of snow. Hand shears or shovel tilt tests can be fast ways to check for this type of layer.

The sun should be out by later Monday but sun effects should be limited since we are barely past the solstice.

Note that northeast winds may increase Monday night and Tuesday so heads up for new wind slab potential on Tuesday.

 

Snowpack Discussion

The Olympic zone is finally getting enough snow to warrant avalanche forecasts for the season. NWAC observer Tyler Reid confirmed on Friday there is now sufficient snow to produce avalanches and get someone in trouble if in the wrong spot.

Here is a video at Hurricane from Friday by Tyler:

A cold front moved over the Northwest on Saturday and Saturday night. West winds changed to northwest, with moderate snow in the Olympics and a cooling trend. It looks like Hurricane picked up about 4 inches of new snow by Sunday morning.

Light west winds are seen at Hurricane on Sunday with no more snow accumulation and cooler temperatures. Tyler gave us an initial report Sunday midday of local denser wind slab near tree line although it is mostly well adhered to underlying snow. Less snow and the cooling trend should help limit the extent and longevity of new slab layers at Hurricane.

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.