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Avalanche Forecast

Archived

Feb 28th, 2016–Feb 29th, 2016

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

Regions

Olympics.

Play it conservative on Monday and give new wind slabs time to settle by avoiding freshly loaded slopes. Wind slab may extend into the below treeline zone as strong winds Sunday and Sunday night transported snow further downslope than usual.

Detailed Forecast

Showers and at times blustery southwest winds Sunday night should quickly ease Monday morning. High clouds from an approaching warm front will spread over the Olympics mid-day. Snow levels will remain relatively cool. 

New wind slab should be sensitive on lee aspects Monday, with significant amounts of new snow transported Sunday and Sunday night. Play it conservative on Monday and give new wind slabs time to settle by avoiding freshly loaded slopes. Wind slab may extend into the below treeline zone as strong winds Sunday and Sunday night transported snow further downslope than usual. Watch for firmer wind transported snow and surface snow cracking as you travel throughout the terrain.

The storm system came in right side up with a cooling trend, so storm slabs will be a lower concern and possible in non-wind affected terrain. 

Snowpack Discussion

Weather and Snowpack

Springlike weather under high pressure Wednesday and Thursday led to abundant sunshine with temperatures climbing into the 40's. This weather allowed for melt-freeze crust formation and varying amounts of wet surface snow depending on slope aspect during the day. A weak front brought mostly light rain to Hurricane Friday night to Saturday morning.

A strong Pacific frontal system blew through the Olympics mid-morning Sunday. Around 8 inches of snow accumulated through Sunday afternoon at Hurricane Ridge with moderate S-SW transport winds.

The mid and lower snow pack along the west slopes should generally be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

NWAC pro-observer Matt Schonwald was at Hurricane Ridge Friday and found mostly consolidated stable snow. N to E slopes had areas of 25-30 cm of wind transported 4F snow well bonded to 1F melt form grains in the upper snow pack. South through west slopes were melted out in some places with shallower dense stable snow in others.

The road to Hurricane Ridge remained closed on Sunday due to the weather. 

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.