Avalanche Forecast

Issued: Jan 19th, 2019 4:43PM

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

dsaly, Avalanche Canada

Lizard-Flathead.

Snow and wind are building slabs over a weak layer. Be cautious in lee terrain, around steep rolls and cross-loaded features.

Summary

Confidence

Moderate -

Weather Forecast

SATURDAY NIGHT: Mainly cloudy. Moderate gusting strong west wind. Freezing level valley bottom, alpine low -8C.SUNDAY: Mostly cloudy with flurries overnight, accumulating 5 cm by Monday morning. Light to moderate northwest wind. Freezing level climbing to 1100 m, alpine high temperature -6 C.MONDAY: Skies clearing throughout the day. Light west wind. Freezing level valley bottom, alpine high temperature -8 C.TUESDAY: Mainly cloudy with isolated flurries, trace accumulation. Freezing level valley bottom, alpine high temperature -6.

Avalanche Summary

Several natural storm slab avalanches size 1.5-2.5 were observed in the region on Saturday, primarily on North to East aspects in the alpine and treeline. Explosives triggered storm slab avalanches to size 2.5 and storm slabs to size 1 were triggered by skiers. Small slab avalanches were reported in the top 10-15 cm of new snow on Friday and Thursday.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

20-25 cm of new snow has buried a layer of large surface hoar crystals and sun crusts. This will create the potential for fast moving sluffs and/or 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), steep south-facing slopes in the alpine (where sun crusts exist), and in wind-loaded terrain.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

20-25 cm new snow has accumulated over weak surface hoar and/or crusts with deeper deposits in wind-loaded features. Touchy slabs can be expected in areas with more than 20 cm of new snow, such as wind loaded slopes.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Avoid shallow snowpack areas where triggering deeper layers is more likely.Watch for signs of instability like whumpfing, hollow sounds, or shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Jan 20th, 2019 2:00PM