Avalanche Forecast

Issued: Mar 17th, 2014 11:27AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

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

Weather Forecast

Overview: A ridge of high pressure will bring dry conditions to the region on Tuesday. A frontal system will bring moderate snowfall on Wednesday before the dry ridge rebuilds on Thursday.Tuesday: Generally clear skies / Light to moderate northwest winds / Freezing level at 1500mWednesday: 10-15cm of snow / Moderate to strong southwest winds / Freezing level at 1400mThursday: Mix of sun and cloud with light flurries / Moderate northwest winds / Freezing level at 600m

Avalanche Summary

In recent days avalanche observations have been very limited, likely because of inclement weather. There was, however, a report of a size 1.5 human triggered slab avalanche in the Harvey Pass area. See our Incident Report Database for more details.

Snowpack Summary

On Sunday up to 40cm of snow fell at higher elevations and was blown by strong winds into much deeper deposits in lee terrain. Snowpack tests suggest there are still likely weaknesses on a graupel layer near the base of the storm snow. The recent accumulations overlie hard rain crusts which exist on all aspects below 2000m and on solar aspects in the alpine. North of Sparwood and in the Crow's Nest Pass area the buried crust seems more specific to previously sun-exposed slopes. Rain below about 1700m continued to saturate the snowpack, and surfaces may now exist as a hard refrozen crust if temperatures dip below freezing.The deep facet/crust persistent weakness buried at the beginning of February, now down up to 150cm, is still producing sudden results in snowpack tests. I would be very leery of any slopes that have not already avalanched as any activity at this interface would be large and destructive. Triggering will become more likely with forecast clearing and solar radiation.Cornices have also become large and unstable.

Problems

Storm Slabs

An icon showing Storm Slabs
Significant storm accumulations from the weekend have created fresh and reactive storm slabs which overlie fairly widespread crusts. Watch for increased triggering in wind-exposed terrain or when forecast solar radiation is strong.
The new snow will require several days to settle and stabilize.>Choose conservative lines and watch for clues of instability.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

An icon showing Cornices
Cornices in the region are now large and fragile. A cornice fall could be destructive by itself, and could trigger a large avalanche on the slope below.
Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating. >

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 4

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
In some areas the deeply buried weak layers that formed in early February are still showing significant reactivity in snowpack tests. Avalanches at this interface would be large and destructive and are possible at all elevation bands.
Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Mar 18th, 2014 2:00PM

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