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Archived

Avalanche Forecast

Mar 20th, 2020–Mar 21st, 2020
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

With increasing cloud cover and slightly cooler temperatures, the potential for solar induced avalanche activity will decrease through the day Saturday. Still watch for signs of instability such as pinwheeling on sun-exposed slopes when the sun feels strong.

Confidence

High - Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

Friday night: Clear. Moderate to strong northwest wind. Freezing level 500 m.

Saturday: Increasing cloud. Strong northwest wind. Freezing level 1100 m.

Sunday: 10-20 cm new snow. Wind easing to light, variable. Freezing level 900 m.

Monday: Mix of sun and cloud. Light northeast wind. Freezing level 1200 m.

Avalanche Summary

Natural loose wet avalanche activity has been observed on sun-exposed slopes during the heat of the day over the last few warm days. A few cornices were also triggered by the warming. Some glide slab activity has been reported recently out of steep terrain where snow sits over smooth surfaces. 

If you decide to travel in the backcountry, consider sharing your observations with us and fellow recreationists via the Mountain Information Network (MIN) to supplement our data stream as operators are shutting down. Even just a photo of what the day looked like would be helpful.

Snowpack Summary

Wind-affected snow surfaces exist in exposed terrain at alpine and treeline elevations from predominantly northeast wind. Previously formed wind slabs have likely bonded given the recent warm temperatures. In sheltered terrain, soft and faceted snow may be found. Clear skies have melted the snow surface on sun-exposed slopes during the day and frozen it into a melt-freeze crust during nights.

A layer of surface hoar crystals is buried around 30 to 60 cm in sheltered areas at and below treeline. See this MIN from the Shames area that shows this layer when it was on the surface, prior to burial on March 9.

An early-season layer of faceted grains and a melt-freeze crust may linger at the base of the snowpack. A large load, such as a cornice fall, has the potential of triggering it.

Terrain and Travel

  • Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
  • Be aware of the potential for large avalanches due to the presence of buried surface hoar.
  • Carefully evaluate steep lines for wind slabs.

Avalanche Problems

Loose Wet

Loose wet avalanche activity is most likely during the heat of the day when clear skies prevail. Avoid overhead exposure on sun-exposed slopes as the snowpack heats up. Note that cornices are also large and could release during daytime heating.

Aspects: South East, South, South West.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

A weak layer of surface hoar crystals is buried around 30 to 60 cm and has been reactive to both human and natural triggers. This weak layer is most problematic in sheltered terrain at treeline elevations, where the surface hoar remains preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3