Avalanche Forecast
Regions: Mt Hood.
New snow and wind will create dangerous avalanche conditions Saturday. You can trigger an avalanche on any steep wind loaded slope. Increasing easterly winds will load unusual aspects and build wind slabs on open slopes below treeline as well as higher terrain during the day. Storm slabs may form in wind sheltered areas below treeline.
Discussion
Snow and Avalanche Discussion
After a long stretch of quiet avalanche conditions, the avalanche hazard is expected to deteriorate Friday night and Saturday as new snow and wind affect the Mt. Hood area. Widespread surface hoar was reported below treeline in the Mt. Hood Meadows area Friday. Storm or wind slabs building on top of weaker snow, whether it's buried surface hoar or near surface facets will be more likely to produce avalanches Saturday. For areas where the new snow stays unconsolidated, loose dry avalanches will become a problem in steep non-wind affected terrain. Â
Snowpack Discussion
Regional Synopsis coming soon.Â
Avalanche Problems
Wind Slabs
Shifting winds will become stronger and more easterly during the day. This should easily transport recent and new low density snow onto a variety of aspects. Wind slabs will likely develop in all elevation bands as winds increase. Approach steep unsupported slopes with wind-drifted snow cautiously, feeling for firm or hollow sounding snow as a sign that wind slabs may be present. You can stay safe by traveling on ridges, wind-scoured areas and any slope less than 35 degrees.
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: All elevations.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
If storm slabs develop Friday night and Saturday, they may be touchy and break more widely than usual where they build over older, weaker snow. Avoid very steep open slopes and convexities and choose simpler terrain if conditions are touchy. Use small test slopes to gauge the storm slab problem.
Loose dry avalanches will continue to be a concern in very steep terrain that isn't wind affected. Keep this in mind around terrain traps; you don't want a small but fast moving avalanche to take you on an unexpecting ride into trees or over a cliff.
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: Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1