Avalanche Forecast

Archived

Jan 20th, 2020–Jan 21st, 2020

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

Stable snow conditions exist after yesterday’s warm temperatures. New snow and wind arriving Tuesday will begin to develop new avalanche problems later in the day. Look for changing conditions throughout the day and stay clear of steep, lee slopes rapidly accumulating more snow than the surrounding slopes.

Discussion

Warm weather and clearing allowed for the snowpack to continue settling and stabilizing. An active cycle of loose wet avalanches also helped stabilize conditions near and below treeline. A slight crust now covers the generally stable snowpack. Upper elevation slopes also experienced some warming, but cold, dry snow still exists under the surface and weak layers in the recent storm snow may still exist.

Clearing on Sunday offered the first look at the upper mountain after an active 10 days of weather. A very large avalanche was observed on the Newton Headwall. It likely occurred during the storm last week, but highlights continued uncertainty about the snowpack at upper elevations.

A very large crown around 10,000’ on the Newton Headwall of Mt Hood which likely occurred during the storm last week. Photo: Kevin Kayl

Debris from the Newton Headwall avalanche in Newton Canyon. Debris filled the valley floor and extends to 5000’! Photo: Nick Burks

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

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.