Avalanche Forecast

Issued: Mar 21st, 2014 9:56AM

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

ghelgeson, Avalanche Canada

Kootenay Boundary.

Watch the temperature and solar warming this weekend, heat and/or direct sun could quickly initiate cornice fall and natural slab avalanche activity.

Summary

Confidence

Fair

Weather Forecast

Synopsis: A ridge builds into the interior this weekend making for a fairly unexciting weather weekend. Look for high cloud, moderate freezing levels and no significant precipitation.Saturday: Freezing Level: 500m - 1100m; Precipitation: Nil; Treeline Wind: Light, SE | Ridgetop Wind: Light, W/SWSunday: Freezing Level: 600m - 1400m; Precipitation: Nil; Treeline Wind: Light, SW | Ridgetop Wind: Light, W/NWMonday: Freezing Level: 1500m; Precipitation: Nil; Treeline Wind: Calm | Ridgetop Wind: Light, W

Avalanche Summary

On Thursday a widespread natural avalanche cycle to size 2.5, averaging size 1.5 was reported. Activity was most prevalent above 1800m on all aspects. It sounds like the majority of the action was on the March 17th crust. There were no reports of anything stepping down to the deeper buried weak layers.

Snowpack Summary

In general about 35cm of new snow fell on Thursday adding to an existing storm slab which formed last weekend. Wind data was scarce on Thursday, although I suspect the new snow exists as a wind slab in exposed lee terrain. Below the recent storm snow you may find weak surface hoar in shaded terrain and a crust on previously sun-exposed slopes. About 60cm below the surface you'll find a strong rain crust which exists on all aspects below 2000m. This crust is widespread in the south of the region where heavy rain fell on March 10. As you head north in the region where the mountains are higher and colder temperatures persisted, this crust is less likely to exist.A facet/crust persistent weakness buried at the beginning of February, now down 70 to 160cm, has been highly variable in terms of reactivity but still shows 'sudden' results in some snowpack tests. In areas where the strong and supportive near surface crust exists, triggering this layer has become unlikely. That said, this layer is still difficult to trust and any avalanche at these deeper, persistent interfaces would be large and destructive.,

Problems

Storm Slabs

Up to 35cm of new snow fell on Thursday adding to an existing storm slab which may be touchy in wind exposed terrain.

Be cautious as you transition into wind affected terrain.>Be aware of the potential for buried surface hoar, and crusts (on solar aspects).>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Watch for loose wet avalanches in steep, sun-exposed terrain. Loose wet avalanches can be pushy and entrain mass quickly.

Avoid exposure to terrain traps and cliffs 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: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The deeply buried weak layers still show "sudden" results in snowpack tests. Triggers for large avalanches on these layers include cornice falls, solar warming, or hitting the wrong place in a thin snowpack area.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>Caution around slopes that are exposed to cornices overhead.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Mar 22nd, 2014 2:00PM