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Avalanche Forecast

Apr 22nd, 2012–Apr 23rd, 2012
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: Northwest Coastal.

Confidence

Fair - Due to limited field observations on Monday

Weather Forecast

A weak Pacific front is expected to approach the Northwest from the south on Sunday. Light precipitation is expected during the day with moderate southeast winds and freezing levels rising to about 1500 metres. A ridge of high pressure is expected to develop on Monday bringing mostly clear skies and drier conditions with light winds.

Avalanche Summary

Spring conditions exist in the region. Exposure to the sun, warm temperatures, and periods of rain are the most likely factors to influence the avalanche danger. If the temperatures go below freezing overnight, strong crusts should develop that are likely to hold the snowpack together. If the sun shines for a few hours, the crusts may break down quickly and moist surface snow avalanches may start running naturally. Continued warming from more sun, rain, or no overnight freeze, may cause surface avalanches to step down and trigger deeper wet slab avalanches. Prolonged warming may cause very deep releases on weak layers that were deposited early in the season, or on depth hoar that developed during the winter. It is important to monitor the temperature and the freezing levels as they may change rapidly from day to day.

Snowpack Summary

As we transition into spring, the surface layers have a great deal of influence on the snowpack. When there is a solid re-frozen surface crust, travel is fast and easy, and the snowpack is held together by the surface cap. Any deeper persistent weak layers are unlikely to fail until the surface cap breaks down from daytime heating. When there is no crust, surface layers and any deeper weak layers may fail, depending on the amount of heat and the triggering force that is applied. If it cools off and snows, new snow and wind slabs may not bond well to the hard spring crusts. For more information on Spring Conditions and ways to mitigate risk, please visit the new Forecasters' Blog Post.

Avalanche Problems

Loose Wet

Loose wet avalanches are most likely during periods of warming from rainfall or sunshine. These can push you around, entrain mass and become surprisingly large.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Wet Slabs

Warm temperatures or rain may continue to weaken the snowpack, leading to full-depth releases. Loose wet slides may step down and propagate larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 6

Wind Slabs

Thin new wind slabs may continue to develop from light precipitation and southwest winds.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 4