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Avalanche Forecast

Archived

Dec 23rd, 2017–Dec 24th, 2017

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.

Recent storm snow should continue to stabilize. Avoid steeper terrain features with firmer wind transported snow. Be prepared to step back from your plans if the next system arrives stronger and sooner than expected. 

Detailed Forecast

The next system should begin to bring light snow to Hurricane Sunday midday and afternoon. Alpine winds should stay fairly light with no great change in snow levels or cool temperatures.

This should mainly continue to allow storm snow accumulated early in the week to stabilize.

But keep an eye out for previous wind slab on Sunday. Winds will have potentially load non-traditional aspects.

Be prepared to step back from your plans if the next system arrives stronger and sooner than expected.

Early season hazards still exist at lower elevations and especially around creek beds that are not filled in.

Snowpack Discussion

Little if any new snow fell at Hurricane in the 24 hours ending Saturday morning.

But about 18 inches fell there early in the week. Cool and fair weather allowed this snow to mostly stabilize Wednesday and Thursday resulting in a decrease in the avalanche danger.

Winds mainly Tuesday redistributed some snow near ridge crests and in exposed terrain.

In general about two feet of snow now sits on the old snow surface from a week ago.

Observations

NWAC pro observer Matt Schonwald was at Hurricane on Saturday and reported evidence of north to east winds but no wind slab or significant shear in the upper snowpack. The structure was generally F over 4F with good bonds to the Thanksgiving crust.

A nice observations for Friday via the NWAC Observations page indicated 70-85 cm of recent storm snow. Tests gave stubborn results for storm slab and there were no natural or triggered avalanches noted.

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.