Avalanche Forecast

Archived

Mar 25th, 2023–Mar 26th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Below Threshold.

Regions

Yukon, Tutshi, Wheaton, White Pass East, White Pass West.

Watch for new snow and southwest winds building fresh thin wind slabs that may be reactive to skier traffic on north and east facing terrain.

Even small wet loose avalanches have the potential to push a skier over a cliff or into a terrain trap. Be cognizant of an increase in sensitivity to triggering and size when temperatures begin to rise and direct sunshine is on steep slopes and features.

Confidence

Moderate

Avalanche Summary

On Friday a few loose wet avalanches were reported on south aspects in the alpine. These avalanches occurred when the sun appeared and were large (size 2).

On Thursday a few loose dry avalanches were reported on all aspects in the alpine. These avalanches were small (size 1.5).

This past week there have been no reports of natural or human trigger avalanches.

Backcountry users may see evidence of a large avalanche cycle from the weekend as they travel through the terrain. These avalanches may have occurred during last week's storm or due to solar input and elevated freezing levels through the weekend.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

Warming daytime temperatures and strong winds have redistributed 50 cm of storm snow creating hard wind affected surfaces in alpine and exposed treeline terrain. In protected areas in the alpine up to 30 cm of relatively undisturbed snow exists. This overlies previously wind affected snow (sastrugi) in exposed areas, faceted snow in sheltered features and in some places old stiff wind slab.

Specific to Haines pass and below 1300 m the 50 cm of storm snow now has a stout and supportive melt freeze crust that has capped it. An additional 5 to 15 cm of new snow now overlies this melt freeze crust.

A buried weak layer of surface hoar can be found about 80 cm deep in Powder Valley, Tutshi, Paddy Peak and Haines pass areas, 150 to 200 cm around White Pass. This layer is most prominent on northerly slopes sheltered from the wind. On other aspects, this layer is a hard melt-freeze crust with weak facets around it. This layer has been most problematic in alpine terrain.

The remainder of the middle of the snowpack is consolidated and strong. Weak faceted grains are found near the base of the snowpack, particularly in thin snowpack areas.

Weather Summary

Saturday Night

Cloudy, isolated very light flurries, trace to 2 cm of accumulation. Light north ridgetop winds. Alpine temperature high -8°C. Freezing levels falling to valley bottom.

Sunday

Cloudy with afternoon clearing, no new precipitation. Moderate north ridgetop winds. Alpine temperature high -8°C. Freezing levels valley bottom.

Monday

Mostly clear, no new precipitation. Light west ridgetop winds. Alpine temperature high -5°C. Freezing levels rising to 500 m.

Tuesday

Mostly clear, no new precipitation. Light west ridgetop winds. Alpine temperature high -4°C. Freezing levels rising to 700 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.