Avalanche Forecast
Regions: Mt Hood.
New storm slab will be the primary avalanche problem Friday due to potentially unstable storm layers. Lingering wind slab from Thursday and Thursday night on lee N through SE slopes will be a secondary avalanche problem near and above treeline. Use extra caution if traveling into the above treeline zone (alpine) as there have not been any recent observations from this elevation band.
Detailed Forecast
Showers should diminish overnight, but a new round of snow should begin by late morning as the parent upper low asscoiated with Thursday's frontal system moves into northern Oregon. Â Snow should become moderate in the afternoon with shifting winds as the low tracks to the SW of Mt. Hood.Â
New storm slab will be the primary avalanche problem Friday due to potentially unstable storm layers. Lingering wind slab from Thursday and Thursday night on lee N through SE slopes will be a secondary avalanche problem near and above treeline.Â
Use extra caution if traveling into the above treeline zone (alpine) as there have not been any recent observations from this elevation band.Â
Snowpack Discussion
Over the last 4 days,  9 - 12 inches of water has fallen at the Meadows and Timberline NWAC stations. Unfortunately for elevations below 7000', the large majority was in liquid form!  8-12" of new snow has fallen since the switch back to snow Wednesday morning with light to moderate westerly transport winds.Â
Avalanche and Snowpack Observations
The Mt Hood Pro Patrol on Wednesday and Thursday reported a generally stable and draining snowpack with wet grains to the ground. The snowpack depth dramatically increases with elevation, with Meadows patrol reporting almost a meter at 6200 ft. New wind slab was developing near and above treeline Thursday on lee easterly slopes, but was generally not found to be reactive with ski cuts or in snowpack tests. Below treeline should still contain ample terrain anchors, but above 5000' there is enough snow to allow small avalanches in specific areas.  No recent observations have been received for the bulk of the above treeline zone due to weather and visibility restrictions.Â
Avalanche Problems
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
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