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Avalanche Forecast

Archived

Apr 3rd, 2022–Apr 4th, 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, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Inland.

Wind slabs may remain reactive especially around ridges and steep, unsupported features or where they have formed over a crust.

Confidence

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

Weather Forecast

Sunday night: Unsettled with isolated flurries, trace accumulation. Moderate southeast wind overnight. Ridgetop low -12 C.

Monday: Unsettled with flurries in the afternoon, trace to 10 cm. Moderate southeasterly wind. Ridgetop high reaching -3 C.

Tuesday: Cloudy with isolated flurries, trace to 5 cm. Moderate westerly wind. Ridgetop high -6 C.

Wednesday: Flurries. Moderate and increasing southeasterly wind. Ridgetop high -6 C.

Avalanche Summary

On Saturday, a small 3 m wide wind slab, 10-30 cm thick, was easily triggered by workers shoveling cornices.

On Thursday, a couple of small (size 1) wind slabs were reactive to skiers, about 15 cm deep on a north aspect. Otherwise, there have been no recent avalanche observations since earlier in the week when natural cornice falls were observed throughout the region.

Snowpack Summary

Recent south-southeast wind redistributed 5-15 cm recent snow into pressed surfaces and wind slab at treeline and higher. Below recent snow, a crust can be found on all aspects and elevations except high north terrain where cold snow prevailed through recent warm temperatures. Large overhanging cornices have also been observed in the region, may be larger and touchier from the recent wind event.

A couple of layers of weak crystals in the upper snowpack appear to be bonding well according to recent observations and snowpack tests. 

Terrain and Travel

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Be alert to conditions that change with aspect and elevation.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

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.