Avalanche Forecast
Regions: Olympics.
Wind slab is the most likely avalanche problem to encounter on Friday in the Hurricane Ridge area. Approach cautiously and watch for firmer wind-transported snow on lee slopes near ridges. Early season terrain hazards still exist, such as poorly covered rocks, vegetation and creeks, particularly at lower elevations.
Detailed Forecast
On Friday, a frontal system should stall over the Olympics and north Cascades before finally sagging south in the late afternoon and evening. Alpine winds generally out of the S-SW will increase late Thursday night and stay elevated through Friday. New and generally shallow storm snow instabilities may develop in the Olympic zone on Friday. However, fresh wind slab may build at higher elevations in all zones during the day.Â
Wind slab is the most likely avalanche problem to encounter on Friday in the Hurricane Ridge area. Watch for firmer wind-transported snow on lee slopes near ridges, generally west through southeast aspects, but expect wind deposited snow on a variety of aspects in areas of more complex terrain.
Early season terrain hazards still exist, such as poorly covered rocks, vegetation and creeks, particularly at lower elevations.
Snowpack Discussion
The great start to the 2017/18 PNW Winter lasted through mid November. Warm, wet weather before Thanksgiving caused wet snow and glide avalanches and snowpack consolidation with total snow depths decreasing by 50% or more from their mid-November peak depths. The old wet snow continues to slowly refreeze and from a crust of variable strength.
A series of fast moving frontal systems have brought several inches of snow to the Olympics and the west slopes of the Cascades this week. Mt. Baker has received the most snow since Monday, about 2 feet. Over at Hurricane Ridge, temperatures have hovered near the freezing mark likely leading to rapid stabilization of the new snow that fell over the course of the week.
Observations
No recent observations from Hurricane Ridge. See Cascade zones for their local observations.Â
Avalanche Problems
Wind Slabs
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.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. 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.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1