Avalanche Forecast

Issued: Mar 19th, 2018 4:57PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada cgarritty, Avalanche Canada

High north aspects continue to hold the best snow as well as a lingering storm slab problem.

Summary

Confidence

High -

Weather Forecast

Tuesday: Cloudy with scattered flurries and a trace to 5 cm of new snow, continuing overnight. Light to moderate southwest winds. Freezing level to 1500 metres with alpine high temperatures around -5.Wednesday: Cloudy with scattered flurries and a trace to 5 cm of new snow, continuing overnight. Light to moderate southeast winds, increasing overnight. Freezing level to 1500 metres with alpine high temperatures around -4.Thursday: Cloudy with isolated flurries and a trace of new snow, increasing overnight. Moderate to strong southeast winds. Freezing level to 1900 metres with alpine high temperatures around 0.

Avalanche Summary

Reports from Sunday included a remotely (from a distance) triggered 25 cm deep storm slab (size 1) releasing with skier traffic on a steeper north-facing slope at around 2000 m in the Monashees. Several more natural size 2 storm slab releases were observed on very steep northeast-facing terrain at around the same elevation. These occurred during the peak of daytime warming.On Saturday there were numerous reports of size 1-2, loose wet avalanches on sunny, solar aspects involving the recent storm storm snow, as well as one report of a size 1.5 skier triggered slab (30 cm deep) on a northwest aspect at 2000 m.Last Friday there were reports of several skier triggered (size 1-1.5) avalanches from 15-25 cm deep on north through southeast aspects between 1700-2100 m.

Snowpack Summary

Recent light snowfalls have been followed by warm daytime temperatures and glimpses of sun, setting up a couple of thin storm snow layers over temperature and sun crusts at lower elevations and on south aspects. On shaded aspects at higher elevations, these snowfalls have buried and preserved a couple of surface hoar layers now found up to 25 cm deep. New snow amounts taper with elevation and below 1800 m, minimal accumulations have buried a supportive crust on all aspects. This crust will likely break down with daytime warming, becoming moist in the afternoon. Deeper persistent weak layers from January and December are generally considered dormant, but could wake up with a surface avalanche stepping down, large cornice fall, or a human trigger in a shallow or variable-depth snowpack area. These layers consist of sun crust, surface hoar and/or facets.

Problems

Storm Slabs

An icon showing Storm Slabs
Isolated pockets of surface hoar on sheltered, high north aspects have led to prolonged reactivity in storm slabs about 25 cm deep.
Be cautious around steep or convex slopes where buried surface hoar may be preserved.Use extra caution in the afternoon if snow becomes moist or wet.Give cornices a wide berth when travelling on or below ridges.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 20th, 2018 2:00PM

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