Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 10th, 2018–Mar 11th, 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 possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Mt Hood.

You will be able to trigger wet avalanches Sunday due to a weak overnight refreeze, warm daytime temperatures, and sunny skies. Stay off of steep sunny slopes where you see signs of wet surface snow. Lingering hard wind slabs may still be found on lee slopes near and above treeline. Avoid steep slopes where recent winds have deposited snow.

Detailed Forecast

Wet snow conditions will develop Sunday creating wet avalanche problems. Stay off of any steep slope where you see signs of wet surface snow.  A weak overnight refreeze will allow this process to occur quickly. You will find wet snow first on steep rocky slopes receiving direct sunshine. Expect unstable conditions to spread as the day warms and freezing levels extend to the top of the forecast area. Expect new roller balls, pin wheels, and loose wet avalanches. As water reaches deeper into the snowpack, wet slab avalanches could occur. If you see signs of any new slab avalanches, step back your terrain use and stay out of avalanche terrain.

Lingering hard wind slabs will still exist at higher elevations. You are most likely to find and trigger these avalanches on shaded slopes not receiving direct sunshine. Firm wind slabs can lure you far onto the slope before failing, creating a particularly dangerous situation. To avoid wind slabs, stay away from any steep slopes where you believe winds have recently deposited snow. If the snow below you feels hollow, seek lower angle terrain.

Limit your exposure to Mt Hood’s very large avalanche paths Sunday. Very large and difficult to predict wind slabs have formed high on the mountain above the forecast area. A very large avalanche initiating high above you may travel to your location. Similarly, limit your exposure to cornices above you. These may fail without warning due to warm temperatures and sunshine.

Snowpack Discussion

Overnight clouds, mild temperatures, and a few passing showers should limit the overnight snow surface refreeze. This will be most pronounced on slopes that received direct sun on Saturday.

Six to eight inches of new snow fell with moderate winds Thursday night and Friday. Before cooling Thursday night, rain reached up to 6600 ft. Winds throughout the storm reshaped the snow surface. Firm wind slabs, snow drifts, and wind scoured surfaces have all been reported.

While we are tracking several layers deeper in the snowpack, there are currently no significant layers of concern.

Observations

NWAC Pro-Observer Laura Green traveled in the Mt Hood backcountry Friday. Laura found moderate to strong winds transporting snow throughout the day. Plumes were seen high on Mt Hood during the morning. She observed a variety of wind featured snow surfaces including large deep snow drifts, hard wind slabs, and uneven snow surfaces near and above treeline.

Problems

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.

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.