Avalanche Forecast
Regions: Mt Hood.
Heightened avalanche conditions will exist on specific slopes Wednesday. You may be able to trigger a lingering Wind Slab avalanche at upper elevations on steep slopes near ridge-tops or in cross-loaded terrain features. Small Loose Wet avalanches are possible on steep sunny slopes near and below treeline, especially if the sun pops out for an extended period of time.
Detailed Forecast
Heightened avalanche conditions will exist on specific slopes Wednesday. You may be able to trigger a lingering Wind Slab avalanche at upper elevations on steep slopes near ridge-tops or in cross-loaded terrain features. Watch for clues like variable snow height, drifts, cornices, and stiff snow that produces cracking. These are all indicators that you could trigger a Wind Slab. You can avoid triggering these avalanches by steering around steep roll-overs, unsupported features, and obvious start zones where you suspect Wind Slabs.
Small Loose Wet avalanches are possible on steep sunny slopes near and below treeline, especially if the sun pops out for an extended period of time. Watch for warning signs like new roller balls, pinwheels, and natural Loose Wet avalanches that indicate increasing hazard. Even small Loose Wet avalanches may carry you into terrain with high consequences such as over cliffs or into gullies.Â
Snowpack Discussion
Moderate West winds were seen near and above treeline Monday and Tuesday, but there was limited new or recent snowfall available to transport. Occasional light rainfall was seen at lower elevations leading to wet snow conditions.Â
Around 12-14" of new snow fell in the Mt Hood area Friday through Saturday at cold temperatures. Soft but sensitive Wind Slabs were reported mainly above treeline Friday and Saturday. Some Wind Slabs released down to the most recent knife hard crust above treeline (See Laura Green's Instagram post).
There are currently no significant layers of concern in the mid or lower snowpack.
Observations
On Tuesday, Mt. Hood Meadows pro-patrol reported moderate west winds near and above treeline but limited snow available to form new wind slabs in their area. Warm temperatures and occasional light rain caused small Loose Wet avalanches on all aspects near and below treeline, but especially on southerly aspects. Â
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: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Elevations: Treeline, Below Treeline.
Likelihood: Possible
Expected Size: 1 - 1