Avalanche Forecast
Regions: Mt Hood.
Expect increasing avalanche danger Wednesday afternoon with new storm and wind slabs developing. Travel conservatively, especially avoiding wind loaded slopes above treeline Wednesday.
Detailed Forecast
New storm and wind slab should build Wednesday afternoon as a Pacific frontal system approaches from the west.Â
Storm slabs should be shallow but should become increasingly sensitive due to a slight warming trend during the day. S-SW transport winds will build wind slab on lee aspects. Watch for signs of cracking or firmer wind transported snow. Older and larger wind slabs may still be sensitive on similar aspects above treeline.Â
New snow may initially bond poorly to a variety of snow surfaces Wednesday. Travel conservatively and expect a rising avalanche hazard later in the day.Â
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Snowpack Discussion
Weather and Snowpack
A strong front crossed the Northwest on Friday January 29th. NWAC stations at Mt Hood had about a foot of new snow by Saturday morning. About another 6-8 inches followed at the tail by Sunday morning. Cool and benign weather settled over Mt. Hood the last few days with ample sunshine on Tuesday.
Recent Observations
On Sunday the Mt Hood Meadows patrol reported limited 4-6 inch wind slab on lee slopes in the above tree line, lower than usual below ridges, which would be small and difficult for a skier to trigger.
A report on Turns All Year for Sunday in Newton Canyon had gradually harder compression tests with depth in right side up storm snow with no signs of propagation.
The Mount Hood Meadows pro-patrol on Monday reported minor wind transport in the above treeline giving isolated, small pockets of wind slab. Also on Monday, NWAC pro-observer Matt Schonwald found wind slab around 7000' on a ESE aspect in White River Canyon failing during snowpit tests at a density change 30-60 cm down. The slab was pencil hardness.  Matt found the wind slab hardness and sensitivity quickly decreased with a loss in elevation.Â
On Tuesday, the Meadows pro-patrol ventured well into their above tree-line terrain (Super Bowl). They found wind slab on lee aspects failing at a density change 40-45 cm down but not particularly reactive in snowpack tests.
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.
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: Likely
Expected Size: 1 - 1