Avalanche Forecast

Archived

Jan 4th, 2018–Jan 5th, 2018

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Mt Hood.

Light snow and wind above treeline may develop small wind slabs during the daylight hours. Monitor changing snow surface conditions throughout the day and be prepared to change your travel based on current conditions.

Detailed Forecast

Light precipitation in the form of rain will continue to break down surface crust causing them to become less supportable at near and below treeline. Loose wet avalanche may occur but would be limited to very isolated terrain where surface snow becomes sufficiently wet to lose cohesion. Loose wet activity is expected to peak during Thursday night and diminish rapidly into Friday.

Above treeline, snow combined with southerly winds will develop small wind slabs on lee slopes during the day. Expect this avalanche problem to continue to grow throughout the day as more snow becomes available for transport by the wind.

Despite all this new snow, early season hazards still exist. Many creek beds have still not filled in for the winter.

Snowpack Discussion

Light rain Thursday began to soften surface crusts on most slopes.

A variety of snow surfaces exist, including wind scoured snow, crusts, and likely stubborn to unreactive wind slabs.

Several rain and freezing rain crusts are sandwiched in the upper snowpack depending on elevation. Current observations do not suggest these layers to be reactive.

Observations

Mt Hood Meadows Ski Patrol reported a melt-freeze crust at the surface Thursday prior to the precipitation event.

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.