Avalanche Forecast

Archived

Mar 13th, 2024–Mar 14th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Regions

Coquihalla, Manning, Skagit.

Sudden warming and sun will cause a natural avalanche cycle on Thursday. Avoid avalanche terrain.

Confidence

High

Avalanche Summary

Reports of avalanche activity have been limited. A notable size 2 persistent slab avalanche was observed in Manning Park and likely occurred over the weekend (photo below).

Looking forward, warming will cause large wet loose, cornice, and slab avalanches.

Snowpack Summary

Sudden warming on Thursday will cause moist surfaces on all but the highest north-facing terrain. 30 to 50 cm of snow from the past few days is rapidly settling, but some storm slab instabilities may still be present. Storm snow sits above a thin sun crust on south aspects.

There has been evidence of two persistent weak layers roughly 80 to 120 cm deep. The upper one is a thin layer of facets and crusts or surface hoar while the deeper one is facets above a thick crust. While we have not seen many reports of persistent slab avalanches in this region, these layers should not be trusted based on notable activity in neighbouring regions.

Weather Summary

Wednesday Night

Clearing skies. 25 km/h north ridgetop wind. Treeline temperature -4 °C.

Thursday

Sunny. 15 km/h north ridgetop wind. Treeline temperature +4 °C with freezing level climbing to 2500 m by midday and 3000 m by the afternoon.

Friday

Sunny. 30 km/h east ridgetop wind. Treeline temperature +6 °C with freezing level climbing to 3400 m.

Saturday

Sunny. 45 km/h east ridgetop wind. Treeline temperature +8 °C with freezing level sustained at 3500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid avalanche terrain during periods of strong sun.
Avoid exposure to overhead avalanche terrain as temperatures increase.
Cornice failure may trigger large avalanches.
In times of uncertainty conservative terrain choices are our best defense.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.