Avalanche Forecast

Archived

Mar 27th, 2018–Mar 28th, 2018

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

Dangerous avalanche conditions will develop Tuesday above treeline as strong winds build fresh Wind Slabs at higher elevations. You can trigger a Wind Slab avalanche at upper elevations on steep slopes near ridge-tops or in cross-loaded terrain features. Rising snow levels will raise the potential for generally small Loose Wet avalanches near and below treeline. Avoid slopes where loose wet avalanches may become large by entraining deeper amounts of recent snowfall.

Detailed Forecast

Dangerous avalanche conditions will develop Tuesday above treeline as strong winds build fresh Wind Slabs at higher elevations. You can trigger a 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.

Rising snow levels will raise the potential for generally small Loose Wet avalanches near and below treeline. Avoid slopes where loose wet avalanches may become large by entraining deeper amounts of recent snowfall. Watch for warning signs like new roller balls, pinwheels, and natural Loose Wet avalanches as temperatures rise and light snow turns to rain. Even small Loose Wet avalanches may carry you into terrain with high consequences such as over cliffs or into gullies

Snowpack Discussion

Moderate West winds continued to transport recent snowfall near and above treeline Monday.

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. These were identified within the ski area and on south-facing backcountry terrain. 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 Saturday, Mt. Hood Meadows Pro patrol reported many small to large skier-triggered and explosive-triggered soft slab avalanches near and above treeline on lee aspects in wind loaded terrrain. Some were remote-triggered.

Problems

Wind Slabs

Wind Slab avalanches are the 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.

Loose Wet

Loose Wet avalanches are the 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. 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.