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Avalanche Forecast

Archived

Jan 18th, 2025–Jan 19th, 2025

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

Regions

Glacier.

Wind slabs are losing their energy, but don't let that lure you into complacency.

Slap on the sunscreen and be sure to travel prepared for these colder temps.

Confidence

Moderate

Avalanche Summary

A field team conducted explosives testing on steep, northerly treeline features today. Results up to size 1.5 were observed, with minimal propagation.

On Thursday, there were several large (up to size 2) natural avalanches in the steep terrain on the N face of Mt MacDonald. These were triggered by the extreme SW winds (up to 125km/hr!)

Snowpack Summary

Up to 10 cm of new snow came in with Extreme SW winds on Thursday. Another 10cm of low density snow buries these wind slabs.

There is a weak interface (Jan 7th layer) down 30-50cm, comprised of surface hoar (all aspects) and/ or a thin crust on steep S aspects.

Overall the mid and lower snowpack is strong and well settled.

Weather Summary

Temperatures remain cold as northern air persists.

Tonight Clear periods. Alpine low -15°C. Ridge winds 10km/h from the NW.

Sun Mainly sunny. Alp low -16°C, high -15°C. Light NE wind.

Mon Mainly sunny. Alpine high -13°C. Light west wind. Alpine temp inversion.

Tues Mainly cloudy. Alpine high -12°C. Winds from the west at 20km/h gusting to 45.

Terrain and Travel Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.
  • Be especially cautious as you transition into wind-affected terrain.

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.