Avalanche Forecast

Archived

Apr 17th, 2023–Apr 18th, 2023

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Alpine

Below Threshold.

Treeline

Below Threshold.

Below Treeline

Below Threshold.

Regions

Chic-Choc Mountains, Littoral, Murdochville.

Avoid exposure to slopes that have cornices overhead.

At this time of year, conditions are changing rapidly, and our observations are limited, please share your observations via the Mountain Information Network at the following address: https://www.avalanche.ca/fr/mountain-information-network/submit.

Confidence

Moderate

Avalanche Summary

Numerous natural wet loose avalanches, up to size 1, as well as cornice breaks, were observed in the alpine on Monday.

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Snowpack Summary

Following the last two days of continuous temperatures above the freezing level, the snowpack is soaked at all elevations, and snow conditions are rather sticky and slow (mashed potato snow). The best chances of finding the classic corn snow are on the polar slopes. In the absence of overnight refreeze, the snowpack becomes progressively more fragile, wetter and less cohesive, and the forecasted rain will only accentuate that, as well as weakening the cornices. The melting is fast and the snow cover varies from 40 cm (valley) to 115 cm (mid-mountain).

Weather Summary

Forecast for the Chic-Chocs ridges and summits.

Synopsis: A deep low pressure system will leave 20 to 25 mm of rain over the next three days.

Monday evening and night: Cloudy. Rain. Winds from 60 to 70 km/h from the south. Min. +3C. Freezing level at 3250 m.

Tuesday: Rain up to 9 mm. Winds around 60 km/h from the southeast, easing off to 40 in the afternoon. Max. +3C. Freezing level at 1700 m.

Wednesday: Mix of rain and snow. Winds from 20 to 30 km/h from the northwest. Max. 0C.

Thursday: Cloudy. Light rain. Winds around 25 km/h from the northwest. Max. -2C.

For more details, see the Chic-Chocs alpine forecast.

Terrain and Travel Advice

A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.

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.

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.

Wet Slabs

Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.