Avalanche Forecast

Archived

Jan 25th, 2018–Jan 26th, 2018

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Olympics.

Dangerous avalanche conditions will persist Thursday, especially in terrain receiving wind transported snow. Lower elevations will begin to slowly stabilize. Avoid steep open slopes in higher terrain. Give safe margins near and below growing cornices. Storm snow is very deep! Tree-well and snow immersion hazards are very dangerous, so keep communication with your partner at all times.

Detailed Forecast

Moderate rain and snow late Wednesday should taper to light to moderate showers with a cooling trend overnight Wednesday and Thursday.

Increasing crest level winds are expected Wednesday night and Thursday.

The avalanche danger will lower slightly Thursday, but mainly at lower elevations with little wind exposure. Near and above treeline, strong winds should continue to build wind slabs along lee slopes below ridges and exposed open terrain.

Dangerous avalanche conditions will persist due to the likelihood for triggering a large and potentially deadly avalanche. Recent storm and wind slabs will require time to heal, so be patient and match your terrain selection appropriately.

Significantly transformed snow conditions have taken place during this extended storm cycle. Tree-well and snow immersion hazards are very dangerous, so keep communication with your partner at all times.

Snowpack Discussion

The NWAC weather station at Hurricane Ridge has received 7 inches of water equivalent over the past 7 days. It appears all that has fallen as snow with the total depth at Hurricane Ridge increasing 40 inches since 1/17.

An estimated 3-4 feet of snow rests above the most recent crust on sheltered slopes. Moderate to occasionally strong S-SW winds have continued to transport new and recent snowfall in the Hurricane Ridge area over the last several days. Two separate avalanche cycles may have occurred since Sunday. New storm snow instabilities have had little time to settle due to the consistent loading in the Hurricane Ridge area during this extended storm cycle.

A high degree of uncertainty exists in this area due to the lack of observations over the last week, however weather station data would support significant storm and wind slabs exist in the Hurricane Ridge area.

Observations

No recent observations

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.