Avalanche Forecast

Issued: Jan 26th, 2015 8:37AM

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

jlammers, Avalanche Canada

Northwest Coastal.

Continued wind, snow and warming will add more stress to buried weak crystals. Very large avalanches have been running from the alpine to valley bottom. Conservative terrain selection remains critical.

Summary

Confidence

Fair - Track of incoming weather systems is uncertain on Monday

Weather Forecast

An active moisture stream will continue to bring moderate snowfall with locally heavy accumulations in the south of the region. Monday night: Up to 30cm of new snow / Extreme southwest winds / Freezing level at 1200m Tuesday: Moderate snowfall in the morning easing by mid-day / Strong southwest winds / Freezing levels at 800m Wednesday: Light snowfall with up to 15cm falling that evening / Strong southwest winds / Freezing level at 800m Thursday: About 10cm of new snow / Extreme southwest winds / Freezing level at 1200m

Avalanche Summary

In recent days, a widespread natural avalanche cycle took place to size 3.5. These avalanches were triggered by loading from heavy precipitation, wind, and warm temperatures. Many avalanches failed within the recent storm snow, although numerous avalanches also failed on persistent and deep persistent layers. At lower elevations where precipitation fell as rain, loose wet avalanches to size 2 were also observed. With ongoing loading from new snow and wind, I expect ongoing storm slab activity with the potential for deeper destructive releases.

Snowpack Summary

Ongoing heavy snowfall (with rain below approximately 1200 m) and extreme southwest winds continue to build fresh deep and dense storm slabs. A rain crust and/or surface hoar layer buried mid-January is buried about 100cm below the surface. This weakness became reactive with recent heavy loading, and has been responsible for much of the recent large avalanche activity. The November crust near the bottom of the snowpack is generally well bonded, but has woken-up in some cases with intense loading and warm temperatures throughout the past week. There is still potential for very large and deep avalanches.

Problems

Storm Slabs

Continued heavy loading from snow and wind will create potent new storm slabs. Watch for increased reactivity in higher, wind-exposed terrain. At lower elevations where rain has fallen, destructive wet slabs are also possible.

Be alert to conditions that change with elevation.>Be cautious as you transition into wind affected terrain.>Good day to make conservative terrain choices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Storm loading and warm temperatures have added reactivity and destructive potential to weak crystals which formed in early January. With more snow on the way, very large avalanches remain a concern with potential to run all the way to valley bottom

Be aware of the potential for large, deep avalanches due to the presence of buried crusts and/or surface hoar.>The new snow will require several days to settle and stabilize.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 7

Loose Wet

The snowpack is saturated at elevations where rain has fallen. If warm temperatures persist, pushy loose wet avalanches will remain a concern in steep terrain. Destructive wet slab avalanches are also possible where the snowpack is rain-soaked.

Be cautious of wet sluffing in steep terrain.>Even small avalanches may run a long ways under the current conditions.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Jan 27th, 2015 2:00PM