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 26th, 2015–Dec 27th, 2015

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

Regions

Olympics.

Lingering storm and wind slabs instabilities will continue to settle on Sunday. Watch for sensitive wind-loaded slopes especially near and above treeline, and stick near your partner to help mitigate the deadly risk of deep snow immersion below treeline.  

Detailed Forecast

A frontal system passing through Saturday night and Sunday should drop a few inches of new snow with moderate southerly transport winds for the Olympics. This system will stack up short compared to some of the burly snow totals received over the last week. 

However, recent cool temperatures should continue to slow the otherwise stabilizing trend in the upper snowpack. 

Recent wind slab will be most likely to linger on north to east slopes in the near and above tree line. Wind and storm slab avalanches should stay within recent storm layers but could still move fast. Test for inverted strong over weak storm snow and give cornices a wide margin.

Beware of loose dry avalanches in steep non-wind affected terrain that could have unintended consequences such as knocking you off your feet and into a terrain trap.

Remember to discuss plans and maintain visual contact with your partners. Recent unconsolidated storm snow is very deep in many places with possible very large tree wells. There have been snow immersion fatalities in tree wells already this season at Snoqualmie and in Canada.

Snowpack Discussion

We have had about a week of heavy snow and cool temperatures in the Olympics and Cascades. The Hurricane Ridge NPS Ranger reported a snowdepth of 87 inches Saturday morning with about 4 feet of new storm snow since the last observation on the 21st. There has been slow settlement over the last few days, but the main message is that it is still deep out there! Unlike last year, there is healthy snowpack below treeline on all aspects.   

The NPS Ranger also reported a widespread natural avalanche cycle had occurred within the last few days within the Hurricane Ridge area, with storm slabs seen on a variety of aspects near and below treeline. 

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 Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.