Avalanche Forecast
Regions: Mt Hood.
Increasing E-SE winds will re-distribute new and recent snow near and above treeline Thursday, continuing the dangerous avalanche conditions in the Mt. Hood area. Large avalanche paths above treeline have the potential for low-likelihood, high consequence slab avalanches that would be unsurvivable. Steer clear of large avalanche paths and choose more moderately angled and supported slopes near and below treeline.
Discussion
Snow and Avalanche Discussion
Since Saturday morning an impressive 4 ft or more of snow has fallen in the Mt Hood area! Thursday will be a mix of new and old avalanche concerns, and rather than trying to manage a complex scenario, it's better to choose simpler terrain not capable of producing large avalanches.Â
The early storm snow fell with cold temperatures and more recent snow with gradual warming and very strong winds Monday night and Tuesday. All this storm snow is sitting on a hard crust and in areas is poorly bonded due to weak faceted crystals that formed on the crust. Widespread natural and controlled avalanches were reported Tuesday at Mt Hood Meadows, some releasing several feet deep to the old snow/crust interface. Less avalanche activity was reported Wednesday, but skier triggered avalanches up to 2' deep were still possible on wind loaded slopes.Â
We've received a lot of snow over the last few days. The risk of tree well and snow immersion suffocation is real in the trees. Don't travel alone and always keep in contact with your partner. You can learn more about deep snow safety here.Â
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Snowpack Discussion
New Regional Synopsis Coming Soon
Avalanche Problems
Wind Slabs
The potential for older, harder, deeper slabs triggered by a human or cornice fall should keep you out of areas where large avalanches can run, start or stop. As the winds increase and shift to the E-SE Thursday, watch for fresh drifting on unusual aspects. Thursday is a good day to choose simpler, less wind affected terrain.
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: Likely
Expected Size: 1 - 2
Storm Slabs
Storm slab instabilities from recent heavy snow are still healing, but in areas where they are poorly bonded to an underlying hard crust, large slab avalanches remain possible. New shallow storm slabs may develop if more than 6 inches of snow piles up quickly Thursday afternoon. Give new and recent storm snow time to settle by sticking to moderately angled and supported slopes.
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.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1