Avalanche Forecast

Archived

Apr 9th, 2022–Apr 10th, 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.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland.

The appearance of the strong April sun may initiate a round of loose avalanche activity. Take care to plot a route that keeps you from being on or under steep south facing slopes and watch for isolated pockets of wind slab, especially around ridge crest.

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

SATURDAY NIGHT: Trace of snow possible, light north wind, freezing level at valley bottom.

SUNDAY: Broken cloud cover in the morning giving way to just a few clouds in the late afternoon, no significant precipitation expected, light east/northeast wind, freezing level beginning at valley bottom, rising to around 1000 m in the afternoon.

MONDAY: Just a few clouds for most of the day with cloud cover increasing to broken in the late afternoon, potential for some light flurries/rain in the afternoon, moderate south wind, freezing level beginning at valley bottom, rising to around 900 m in the afternoon.

TUESDAY: A few clouds, no significant precipitation expected, strong east/northeast wind, freezing level at valley bottom.

Avalanche Summary

On Friday we received some observations of an avalanche cycle that occrued during the storm which produced avalanches up to size 3. Activity is expected to continue to decrease with the warm to cool temperature trend.

On Thursday, reported avalanche activity included pinwheeling on south facing slopes and some loose dry avalanches in steep terrain. A size 2 skier triggered storm slab at 1300 m was also reported.

On Wednesday, a large (size 2) wind slab released naturally on an east aspect in the alpine. A small (size 1) wind slab avalanche was observed in a cross-loaded feature near ridgetop.

Snowpack Summary

10 to 50 cm of recent storm snow overlies a hard melt-freeze crust. (In some of the snowier places in the region, you may find as much as 80 cm over the crust.)

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.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Brief periods of sun could quickly initiate natural avalanche activity.
Recent wind has varied in direction so watch for wind slabs on all aspects.

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.

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.