Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 27th, 2017–Dec 28th, 2017

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

Regions

Olympics.

As we enter a storm cycle Thursday, human triggered avalanches will become more likely as denser but shallow storm snow builds over weaker snow during the day. Especially watch for building wind slab on a variety of aspects near and above treeline where there is plenty of low density snow available to transport onto lee slopes. Watch for changing conditions, travel conservatively and rein in your plans if conditions deteriorate faster than expected.

Detailed Forecast

As we enter a storm cycle Thursday, human triggered avalanches will become more likely as denser but shallow storm snow builds over weaker snow during the day. Shallow storm slabs may become touchy by the end of the day. Especially watch for building wind slab on a variety of aspects Thursday predominately near and above treeline where there is plenty of low density snow available to transport onto lee slopes.

Loose wet avalanches are mostly likely encountered below treeline on steeper slopes due to warming and light rain. Avoid terrain traps where even a small loose wet avalanche could be problematic.    

Watch for changing conditions, travel conservatively and rein in your plans if conditions deteriorate faster than expected. See the mountain weather tab for weather forecast details. 

Also despite all the new snow, early season hazards still exist at some lower elevation locales and especially around creek beds that are not filled in.

Snowpack Discussion

Our last major storm cycle ended 12/19-12/20. Since then a series of weak weather disturbances have traversed the area over the last week, depositing about 6 inches of low density snow at Hurricane Ridge. 

Observations

A second hand report of at least one human triggered loose dry avalanche (sluff) caught a skier(s) on Sunday 12/25. No injuries were reported. 

NWAC pro observer Matt Schonwald was at Hurricane Ridge on Saturday 12/24 and reported evidence of north to east winds but no wind slab or significant layers in the upper snowpack. The snowpack structure was generally right-side with good bonds to the Thanksgiving crust.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.