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Avalanche Forecast

Archived

Apr 25th, 2024–Apr 28th, 2024

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.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Below Threshold.

Regions

Haines Pass.

Triggering a buried weak layer remains possible. Watch for warming-related problems as the day heats up.

Confidence

Moderate

Avalanche Summary

We haven't received reports of avalanche activity for the past few days, but check out this MIN that discusses whumpfing. The latest avalanche activity on the weak layer described in the Snowpack Summary occurred on Saturday.

Looking forward, it remains possible for humans to trigger this weak layer. Warming-related problems such as wet loose, wet slab, and cornice releases will also increase with daytime warming. Small storm-related problems could develop on Sunday.

Snowpack Summary

Sun-exposed slopes have a surface melt-freeze crust that turns moist during daytime warming. Shaded alpine slopes have a settled snow surface with potential surface hoar growing on top. Sunday's snow will accumulate on these surfaces.

A layer of surface hoar or facets associated with a crust may be found about 30 to 70 cm deep.

Cornices are large and looming at this time of year.

Weather Summary

Thursday Night

Clear skies. 5 km/h west ridgetop wind. Treeline temperature -1 °C.

Friday

Sunny. 10 km/h south ridgetop wind. Treeline temperature 2 °C. Freezing level 1500 m.

Saturday

Partly cloudy. 10 to 20 km/h southeast ridgetop wind. Treeline temperature 2 °C. Freezing level 1500 m.

Sunday

Cloudy with 5 to 10 cm of snow. 10 to 20 km/h south ridgetop wind. Treeline temperature -1 °C. Freezing level 1100 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
  • Be alert to conditions that change with elevation and sun exposure.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

Problems

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.