Avalanche Forecast

Archived

Dec 12th, 2022–Dec 13th, 2022

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Coquihalla, Manning, Skagit.

The potential for a temperature inversion and sun on Tuesday means loose avalanches may occur on steep slopes. Be alert to changes in aspect, elevation, and time of day.

The snowpack is shallow and early-season hazards are abundant, travel carefully!

Confidence

Moderate

Avalanche Summary

On Saturday, a natural storm slab avalanche was observed on a west aspect at treeline.

On Monday, several natural size 1 glide slab avalanches were observed below treeline on rock slabs near the highway.

Looking forward to Tuesday, the avalanche problem will likely be more confined to wind-loaded areas at upper elevations.

Observations are limited this time of year. Keep posting your observations to the MIN; it helps strengthen our information gathering.

Snowpack Summary

In deeper zones near ridges, the snowpack is around 120 to 170 cm, which is low for early December. Alpine terrain in windy areas is scoured and bare.

Surface: Boot top powder in deep areas. Same old crusts, facets, and rocks on wind-scoured slopes.Upper-pack: In sheltered areas below the fresh snow is well-developed surface hoar. Generally, there's 40 to 70 cm of low-density and faceting (aka weak) snow in the upper pack.Mid-pack: November crust, with a layer of soft facets above. This is the primary weak layer, found pretty much halfway down.Lower-pack: a mixture of old crusts and facets but some suggest that these layers are a bit harder or stronger than what's found in other regions (e.g. Duffy or Hurley).

Weather Summary

Monday night

Cloudy with clear periods. Alpine temperatures drop to a low of -6 °C. Ridge wind light to 15 km/h from the north. Freezing level at valley bottom.

Tuesday

Cloudy with sunny periods. Alpine temperatures reach a high of -3 °C. Ridge wind northwest 15 km/h. Freezing level rises to 900 metres.

Wednesday

Sunny with cloudy periods. Alpine temperatures reach a high of -3 °C. Ridge wind northeast 25-40 km/h. Freezing level rises to 900 metres.

Thursday

A mix of sun and cloud. Alpine temperatures reach a high of -4 °C. Ridge wind northeast 25 km/h. Freezing level rises to 600 metres.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Back off slopes as the surface becomes moist or wet with rising temperatures.
Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
The best and safest riding will be on slopes that have soft snow without any slab properties.

Problems

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.

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.