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Avalanche Forecast

Archived

Apr 19th, 2024–Apr 20th, 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.

Large persistent slab avalanches may remain possible to human trigger on steep slopes in the alpine.

Choose conservative terrain and watch for clues of instability.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported in this region on Thursday.

Please consider sharing your observations to the Mountain Information Network.

Snowpack Summary

A mix of wind affected and soft snow can be found in the alpine. Sunny aspects have a crust on the surface that may soften with daytime heating.

Numerous large persistent slab avalanches were reported last week on a weak layer of surface hoar down 30 to 70 cm.

Cornices are large and looming at this time of year.

Weather Summary

Friday night

Clear skies. 10 to 20 km/h southeast ridgetop wind. Treeline temperature around +3 °C. Freezing level 1600 m.

Saturday

Sunny. 5 to 10 km/h variable direction ridgetop wind. Treeline temperature +4 °C. Freezing level 1700 m.

Sunday

Sunny. 10 to 20 km/h west ridgetop wind. Treeline temperature +2 °C. Freezing level 1500 m.

Monday

Mostly cloudy. 10 to 20 km/h southeast ridgetop wind. Treeline temperature 0 °C. Freezing level 1200 m.

Check out the Mountain Weather Forecast for additional weather information.

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.
  • Choose conservative terrain and watch for clues of instability.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Cornice failures could trigger very large and destructive avalanches.
  • 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.