Avalanche Forecast

Archived

Apr 6th, 2022–Apr 7th, 2022

Alpine

Natural avalanches possible, human triggered probable.

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.

Up to 15 cm snow will fall by the end of the day on Thursday with moderate to strong southwest wind. Wind slabs will form throughout the day and be reactive to human triggers.

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

Wednesday night: Cloudy, up to 5 cm snow, strong southwest wind, alpine low -4 °C, freezing level around 800 m.

Thursday: Cloudy, 5-10 cm snow, moderate southwest wind, alpine high 0 °C, freezing level around 1300 m.

Friday: Mix of sun and cloud, 5-10 cm snow, moderate to strong westerly wind, alpine high -2 °C, freezing level around 1000 m.

Saturday: Mix of sun and cloud, trace of new snow, moderate west wind, alpine high -6 °C, freezing level around 700 m.

Avalanche Summary

On Wednesday, a small (size 1) wind slab avalanche was observed in a cross-loaded feature near ridgetop.

A naturally triggered size 2 wind slab avalanche was reported on a steep cross-loaded alpine feature on Tuesday. Many small dry loose avalanches were observed as well.

Snowpack Summary

The new snow will add to the 10-40 cm of recent snow which overlies a hard melt-freeze crust.

Recent moderate southwest winds removed the snow above the crust in wind-exposed areas and formed wind slabs on lee terrain features at treeline and above.

Cornices are very large and exposure to them should be minimized, especially during warm or windy weather.

Terrain and Travel

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Wind slabs may be poorly bonded to the underlying crust.
Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
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.