Avalanche Forecast
Regions: Mt Hood.
A mix of winter and spring avalanche conditions is likely mainly above treeline at Mt Hood on Sunday.
Detailed Forecast
Southwest flow on the west side of an upper ridge will continue to carry frontal moisture mainly to BC through Sunday. Expect some occasional light showers in the Olympics and northwest Cascades with fair conditions further south at Mt Hood.
It is spring and despite the moderate temperatures the sun will have more effect on the snow pack. The main avalanche problem should be loose wet avalanches. Watch for possible wet surface snow deeper than a few inches, increasing snow balling or natural loose wet avalanches. While this problem should be mainly on solar slopes watch for it on all steep slopes.
Wind slab may linger on lee slopes mainly above tree line. Watch possible for firmer previously wind transported snow mainly on north to east aspects.
Cornices won't be listed as an avalanche problem. But avoid slopes below cornices and ridges or summits where cornices may be hard to see.
Snowpack problems at Mt Hood for the time being should be in the upper or surface layers. The mid and lower snowpack at Mt Hood consists of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
The snowpack at low elevations at Mt Hood remains meager to non-existent.
Snowpack Discussion
Winter made a bit of a comeback in the Northwest in mid to late March. Several storms or storm cycles brought heavy snow to the above treeline areas west of the crest especially on the volcanoes.
A warm front caused pretty heavy rain mainly west of the crest Wednesday to Thursday morning. This caused an avalanche cycle and consolidation west of the crest with the most avalanches at Mt Rainier.
Very warm weather Thursday and Friday mainly caused more consolidation.
A vigorous front and short wave crossed the Northwest Friday night causing strong west-southwest winds, some rain and snow and lowering snow levels. Snow levels lowered enough by Saturday to cause up to 2-3 inches of snowfall at higher NWAC stations west of the crest and at Mt Hood and likely a few more inches at higher elevations.
Avalanche Problems
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.
Aspects: South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
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: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1