Avalanche Forecast

Issued: Apr 11th, 2014 9:42AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs, Deep Persistent Slabs and Loose Wet.

swerner, Avalanche Canada

Northwest Coastal.

Winter transitions into spring! Rapid warming and intense solar radiation can increase the avalanche danger quickly. Check out the new Forecaster Blog which is directly focused on the Northern Regions.

Summary

Confidence

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

Weather Forecast

A strong ridge, with a northwest flow dominates the region bringing clear skies and rapidly rising freezing levels. Saturday: Mainly sunny. Alpine temperatures high of 7.0 degrees. Ridgetop winds light from the NW. Freezing levels near 1700 m rising to 2000 m overnight.Sunday: Mainly sunny skies. Alpine temperatures high of 9.0 degrees and freezing levels rising to 2000 m. Ridgetop winds light from the SW.Monday: Mainly cloudy with isolated precipitation. Alpine temperatures high of 9.0 degrees and freezing levels 2400 m. Ridgetop winds light from the SW.

Avalanche Summary

Numerous loose wet naturals, and wet slabs were reported up to size 2 from steeper start zones at treeline and below treeline. Natural avalanche activity will likely continue through the weekend with sunny skies and a rapid rise in freezing levels.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.

Snowpack Summary

The recent storm has brought 90+ cm or more too coastal regions (80-120 mm) forming thick storm slabs and wind slabs on leeward features. Warmer temperatures have helped to settle the recent snow. At lower elevations the snowpack has become moist, wet and saturated from rain. Large cornices have formed and loom over slopes below.Several persistent weak interfaces exist deeper in the snowpack. The early March layer can be found down 75 -140 cm. The early February layer is down 150 - 240 cm. These layers have become overloaded and are failing in some places initiating very-large avalanches.

Problems

Storm Slabs

Snow driven by strong winds have built storm and wind slab problems at higher elevations. Warmer temperatures and solar radiation will initially de-stabilize the new snow and likely activate a natural avalanche cycle. Cornices may fail with warming.

Avoid all avalanche terrain during periods of warmer and intense solar radiation.>The new snow will require several days to settle and stabilize.>Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 6

Deep Persistent Slabs

Persistent weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a surface avalanche in motion, or a rapid warm-up. Avalanches failing on these weak layers will be large and destructive.

There is potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 7

Loose Wet

With warming and intense solar radiation a loose wet avalanche cycle will be likely, especially on solar slopes.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Minimize/ avoid exposure to avalanche paths, road cut banks and steep slopes at treeline and below.>Indicators of the snowpack becoming weak is moist or wet snow surface snow, snowballing, larger pinwheels and of course natural avalanche activity. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Apr 12th, 2014 2:00PM