Avalanche Forecast
Regions: Mt Hood.
Watch for recent shallow wind slabs that may have formed on the lee, northerly-easterly aspects below ridges, mainly near and above treeline.
Detailed Forecast
Cooling overnight Friday and Saturday with a weak system, depositing shallow new snow in showers Saturday with light winds, should all lead to an overall stabilizing snowpack. Any previously wet or moist surface snow may begin to form a thin surface crust, locally decreasing danger. Further continued snowpack settlement should also allow for an improving trend.Â
New, shallow wind slab may begin to build on lee easterly slopes near and above treeline Saturday, but should be isolated to specific terrain features.Â
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Snowpack Discussion
A continuous period of active weather for about the past week has brought several feet of snow to NWAC stations at Mt Hood. Fluctuating snow levels over this period has occasionally mixed rain up into the near treeline elevation band earlier in this storm cycle.
Roughly 2 feet of new snow accumulated Tuesday and Tuesday night at Timberline and Meadows NWAC base stations with consistent westerly transport winds buffeting the near and above treeline that continued through Wednesday afternoon. Â
Meadows pro-patrol reported an active day of avalanche control on Wednesday with all the new snow. Storm and wind slab releases, mostly initiated with explosives, but also sensitive to ski cutting, ranged from 1 to 3 feet, with the larger slabs on lee aspects near and above treeline. Wind affects were seen well into the below treeline band, and also allowed hard slabs to form on lee slopes higher in the terrain. Debris from a natural avalanche was observed in White River Canyon at around 8000'.
Periods of light precipitation and high freezing levels were seen on Thursday and early Friday along with moderate and consistent SW winds near and above treeline. Â
Reports from Thursday and Friday indicated the snowpack has stabilized significantly over the past two days following the warm temperatures and the addition of light rain.  Shallow moist to wet surface snow is well bonded to settling and supportive over storm snow. Little to no avalanche activity occurred Friday as reported by Meadows patrol with shallow wet snow that did not wish to move below treeline and stabilizing the storm snow at higher elevations also reluctant to move. There is a wide variety of surface snow conditions from wind buff, shallow crusts or wet surface snow, among potential other surface conditions.Â
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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: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1