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Avalanche Forecast

Archived

Apr 19th, 2022–Apr 20th, 2022

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.
Alpine
Natural avalanches unlikely.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Coastal.

A bit of new snow has introduced manageable wind slab and wet loose hazards in the areas it fell. Avalanche activity is unlikely where it didn't.

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Cloudy with diminishing flurries and a trace of new snow. Moderate to strong south winds, easing into the morning.

WEDNESDAY: Clearing. Light to moderate east winds. Treeline high temperatures around 0.

THURSDAY: Mainly sunny. Light east winds shifting southwest. Treeline high temperatures around 0.

FRIDAY: A mix of sun and cloud with cloud increasing. Light southwest winds. Treeline high temperatures around 0.

Avalanche Summary

No new avalanches were reported on Monday. Sunday's reports included one observation of a large (size 2.5) natural cornice fall northwest of Terrace, a great reminder of continuously looming cornice hazards. Late in the afternoon, wet loose releases reaching size 2.5 (large) were observed on steep south aspects in the Icy Pass area. 

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, a vary large (size 3.5) natural cornice failure triggered a deep slab on the steep slope below which ran full path.

Numerous natural wind slabs (size 1.5-3) were observed in the alpine on Monday through Wednesday last week as a result of northeasterly outflow winds.

Snowpack Summary

Light new snow amounts from Monday night through Tuesday have mainly buried heavily wind-affected surfaces in open areas, the product of strong outflow wind early last week. In sheltered areas, the flurries may have added to limited stashes of soft, potentially faceted snow. After daytime warming and a subsequent freeze on Wednesday, it will add to the growing tally of crusts on solar aspects.

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 unstable snow on specific terrain features, especially when the snow is moist or wet.
  • Carefully evaluate steep lines for wind slabs.

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.

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.

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.