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Archived

Avalanche Forecast

Apr 12th, 2014–Apr 13th, 2014
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

The timing of the this weekend's big warm-up is difficult to forecast. If Sunday ends up being the warmer day, Sunday's avalanche danger may be higher than posted.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Sunday: Clear skies / Light and variable winds / Freezing level at about 2000mMonday: Clear with increased cloud late in the day / Light to moderate southwest winds / Freezing level at about 1500mTuesday: Overcast skies with very light precipitation / Light westerly winds / Freezing level at about 1300m

Avalanche Summary

In recent days numerous loose wet, and wet slab avalanches were reported up to size 2 from steeper start zones at treeline and below treeline. A widespread natural avalanche cycle up to size 4 occurred over the past 5 days and deep persistent weak layers became overloaded, initiating very-large avalanches. In shallower snowpack areas, storm slab avalanches have stepped down to the December facet/ depth hoar layer. Natural avalanche activity will likely continue through the weekend with sunny skies and a rapid rise in freezing levels.

Snowpack Summary

A recent storm has brought 90+ cm or more to coastal regions forming thick storm slabs on leeward features. Warmer temperatures have helped to settle the recent snow, although the storm snow may continue to be touchy where it overlies surface hoar, crusts and/or facets buried on April 2nd. At lower elevations the snowpack has been saturated by rain and may exist as wet snow or a refrozen crust. Large cornices have formed and loom over slopes below.The early February crust/facet layer is down 150 - 240 cm. This layer has become overloaded by recent storm loading and is failing in some places resulting in very-large avalanches.

Avalanche Problems

Storm Slabs

Snow and strong winds have built deep storm slabs at higher elevations. Warmer temperatures and solar radiation will likely de-stabilize the new snow and activate a natural avalanche cycle. Cornices may also fail with warming.
Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5

Deep Persistent Slabs

Deep persistent avalanches would be very large and highly destructive. Possible triggers include cornice fall, a surface avalanche in motion, warming and intense solar radiation.
Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>There is potential for large, deep avalanches due to the presence of buried facets and surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 7

Loose Wet

Watch for loose wet avalanches with daytime warming on steep, sun-exposed slopes. Loose wet avalanches can be pushy and entrain mass quickly.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4