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Avalanche Forecast

Archived

Apr 17th, 2022–Apr 18th, 2022

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

Regions

Northwest Coastal.

Last weeks's torrent of outflow wind didn't leave behind much loose snow to transport. This means Monday's resurgence in wind probably won't increase avalanche danger.

Be sure to check out the newest forecaster blog as you plan your spring objectives.

Confidence

High -

Weather Forecast

SUNDAY NIGHT: Clear. Light south winds shifting east and increasing.

MONDAY: Becoming cloudy with light flurries beginning in the afternoon with a trace of new snow. Moderate to strong east winds. Treeline high temperatures around -2.

TUESDAY: Mainly cloudy with 5-10 cm of new snow from overnight. Light to moderate east winds, increasing over the day. Treeline high temperatures around -3.

WEDNESDAY: Clearing with another 5cm of new snow from the overnight period. Light east winds. Treeline high temperatures around 0.

Avalanche Summary

No new avalanches were reported on Friday, however a few new and recent cornice releases were observed, failing to trigger slabs on slopes below. Saturday's reports included observations of an older natural size 3 (very large) wind slab as well as pinwheeling and minor point releases from steep solar terrain.

On Thursday, explosives triggered wind slabs size 1-2 on south-southeast aspects. A skier triggered a size 1 wind slab on a northwest aspect at 1700 m. Additionally, a vary large (size 3.5) natural cornice failure triggered a deep slab on the steep slope below which ran full path. On Wednesday in the north of the region, several natural wind slabs (size 1.5-2) were observed in the alpine as a result of strong outflow winds loading west-facing aspects. One natural cornice failure was also observed (size 2.5) that did not pull a slab on the slope below.

Numerous natural wind slabs (size 2-3) were observed in the alpine on Monday and Tuesday as a result of northeasterly outflow winds. Wind slabs may still exist in lee areas in the alpine and exposed treeline. Riders should minimize overhead exposure to cornices and give them a wide berth when travelling at ridge crest. 

Snowpack Summary

Open terrain has been affected by strong outflow wind that scoured east-facing slopes and loaded snow onto west-facing slopes early last week. Sheltered areas may still have soft snow. Below 1200 m, a widespread crust exists on the surface. Above 1200 m, 40 to 80 cm of settled storm snow rests on a hard melt-freeze crust from late March. The snow has been bonding to this crust.

Terrain and Travel

  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.

Problems

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

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.