Avalanche Forecast
Regions: Mt Hood.
Look for signs of recently wind transported snow such as snow drifts, fresh cornices, and uneven snow surface textures. Identify and avoid wind loaded snow on lee and cross loaded slopes.
Detailed Forecast
Mild weather continues Monday with generally sunny skies.
Recently formed wind slabs will continue to be a problem,especially at higher elevations. Look for signs of recently wind transported snow. Identify and avoid wind loaded terrain below ridgelines and cross loaded terrain features. While we expect wind slabs to primarily exist above treeline, keep a watchful eye out for exposed terrain features near treeline where wind slabs may have formed.
Wind slabs can be deceptively difficult to manage in the terrain. Take a moment and read our recent blog post by NWAC Pro Observer Jeremy Allyn on wind slabs.
Snowpack Discussion
Happy New Year from your friends at the Northwest Avalanche Center!
Winds continued to transport snow at higher elevations in the Mt Hood area Sunday creating a variety of snow surfaces including wind scoured snow, crust, and firm wind slabs.
At lower elevations recent rain created a breakable melt-freeze crust. Several inches of soft snow sit atop this 12/30 crust.
A variety of rain and freezing rain crust exist in the upper snowpack depending on elevation. Current observations do not suggest these layers to be reactive.
Observations
An observation submitted through our public observation page continued to show building wind slabs new Timberline Lodge Sunday. These winds slabs were reported as reactive to ski travel.
Photo: Wind transporting snow on Mt Hood near Timberline Lodge Sunday December 31, 2017.
On Sunday Mt Hood Meadows Patrol reported a breakable crust below treeline. They observed isolated wind slabs and very firm crust at higher elevations.
On Saturday Mt Hood Meadows Pro Patrol reported a large natural avalanche in Clark Canyon. Debris from this avalanche ran into the near treeline elevation band. While the exact depth of the avalanche is unknown, this was a very large natural avalanche.
Photo: Brian Murphy, Mt Hood Meadows Patrol. Avalanche debris in Clark Canyon from a recent very large natural avalanche.
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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: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1