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Avalanche Forecast

Archived

Apr 17th, 2022–Apr 18th, 2022

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

Regions

South Coast Inland.

Fresh snow brings fresh potential for reactive wind slabs to build. Watch for wind affected snow as you move to higher elevations. 

Cornices remain a hazard - manage your exposure as you move below them on slopes, and as you travel along ridgelines. 

Confidence

Moderate - Forecast snowfall amounts are uncertain. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

SUNDAY NIGHT: Mostly cloudy. Moderate south/south easterly winds. Freezing levels fall to 1000 m by morning. 

MONDAY: Snow begins early morning with 5-10 cm expected. Freezing levels reach 1500 m. Strong southeast winds ease over the day. A further 10-20 cm is possible overnight. 

TUESDAY: Cloudy up to 5 cm of snow over the day. Freezing levels reach 1000 m. Moderate westerly winds. 

WEDNESDAY: Clearing skies with no snowfall expected. Moderate easterly winds. Freezing levels rise to 1300 m.  

Avalanche Summary

On Saturday, small wet avalanches were reported on south facing terrain features, during strong afternoon sunshine. 

Several cornice falls have been reported over the last 5 days, indicating that they are weak and responsive to natural and human triggers. 

Snowpack Summary

Up to 10 cm of new snow is expected by Monday afternoon. This is expected to form small wind slabs in exposed terrain features at higher elevations, mainly on west and north facing slopes, as strong south-southeast winds are forecast. These wind slabs will form over wind affected surfaces, and on a crust on south facing slopes. 

The mid and lower snowpack is considered strong at this time, consisting of hard snow and melt freeze crusts. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • 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.
  • Large cornice falls are dangerous on their own.

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.