Avalanche Forecast
Regions: Mt Hood.
Wind slab is the most likely avalanche problem to encounter on Friday and mainly above treeline. 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 Washington Cascades before finally sagging south overnight to Mt. Hood. Unfortunately, this system is not expected to bring any meaningful snow to Mt. Hood. Alpine winds generally out of the SW will increase late Thursday night and stay elevated through Friday. However, fresh wind slab may build at higher elevations during the day.Â
Wind slab is the most likely avalanche problem to encounter on Friday and mainly above treeline. Watch for firmer wind-transported snow on lee slopes near ridges, generally northwest 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 along the west slopes of the Cascades.
A series of fast moving frontal systems brought several inches of snow to the Mt. Hood area.  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
On Wednesday, a professional ski patroller from Mt Hood Meadows toured to about 6600 feet, finding about 8-12" of recent storm snow well bonded to the crust from last week. Storm snow was deepest on N-E facing terrain and no avalanches were noted. Some rollerballing was noted on steep solar terrain due to direct sun warming.  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, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1