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Avalanche Forecast

Archived

Apr 18th, 2022–Apr 19th, 2022

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

Regions

South Coast Inland.

Forecast snow and strong southwest winds Monday night may form wind slabs reactive to human triggers.

Expect the danger to be Considerable in localized areas that receive more than 20 cm of new snow Monday night.

Confidence

High -

Weather Forecast

Monday night: Snow; 10-15 cm / Strong southwest wind / Low of -9 / Freezing level 900 m.

Tuesday: Mix of sun and cloud / Light southwest wind / High of -1 / Freezing level 1400 m.

Wednesday: Sunny / Light southeast wind / High of 3 / Freezing level 1800 m.

Thursday: Mix of sun and cloud / Light southwest wind / High of 2 / Freezing level 1700 m.

Avalanche Summary

No new avalanches were reported on Sunday.

Snowpack Summary

10-15 cm of new snow and strong southwest winds are forecast for Monday night. This may form small wind slabs reactive to human triggers on lee features at treeline and above.

The recent snow is sitting on a variety of hard snow surfaces, including crusts and wind scoured snow. Below this, there are several crusts in the upper snowpack, but they are unlikely to be a concern in most areas until the next significant warming event.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Use ridges or ribs to avoid areas of wind loaded snow.
  • Make observations and assess conditions continually as you travel.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

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.

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.