Avalanche Forecast

Issued: Jan 20th, 2019 3:14PM

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

Avalanche Canada dsaly, Avalanche Canada

Snow and wind continue building touchy slabs over a weak layer. Be cautious in wind-loaded areas where the deepest deposits of snow accumulate, these are the most suspect.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SUNDAY NIGHT: Mostly cloudy with scattered flurries, trace to 10 cm. Light to moderate northeast wind. Alpine low -10C.MONDAY: Mix of sun and cloud. Light north-northwest wind. Alpine high -10C.TUESDAY: Mainly cloudy with isolated flurries, trace accumulation. Moderate west-southwest wind. Alpine high -7C.WEDNESDAY: Cloudy with scattered flurries, up to 10 cm accumulation. Moderate west-southwest wind. Alpine high -4C, freezing level climbing to 1100 m.

Avalanche Summary

On Friday, several natural storm slab avalanches size 1.5-2.5 were observed in the region, primarily on North to East aspects in the alpine. Explosives triggered storm slab avalanches to size 2.5 and skiers triggered avalanches to size 1.5.Two large snowmobile triggered avalanches were reported last weekend. One was triggered on a thin, rocky, southwest facing feature near ridge crest north of Fernie (see here for report). The other was triggered on a wind affected south facing slope at treeline in the Corbin area (see here for report). Deep persistent slab activity this season has been most common in parts of the region with shallow snowpacks (such as near the continental divide) and on alpine features with thin variable snowpack depths.

Snowpack Summary

10-40 cm recent snow has buried a layer of large surface hoar crystals and sun crusts. This has created the potential for fast moving sluffs and slab avalanches with wide propagations. The most suspect terrain features will be steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist). Winds have begun to redistribute snow to lee and cross loaded areas, and build up cornices.In shallow snowpack areas, the base of the snowpack may still be composed of weak faceted grains. In deeper snowpack areas, the middle and lower portions of the snowpack are generally considered to be well-settled and strong.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 40 cm snow has accumulated over weak surface hoar and/or crusts. Deeper and more sensitive deposits are found wind-loaded terrain.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Watch for signs of instability such as whumpfing, or cracking. Give cornices a wide berth when travelling on or below ridges.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 2.5

Valid until: Jan 21st, 2019 2:00PM