Avalanche Forecast

Issued: Feb 28th, 2019 4:31PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

kdevine, Avalanche Canada

Lizard-Flathead.

Human triggered avalanches remain possible, especially in wind loaded areas and at lower elevations where buried surface hoar layers exist.

Summary

Confidence

Moderate -

Weather Forecast

THURSDAY NIGHT - Cloudy with scattered flurries, 5-10 cm / southwest winds 10-20 km/h / alpine low temperature near -13FRIDAY - Mainly cloudy with isolated flurries, 5 cm / east winds 10-20 km/h / alpine high temperature near -13SATURDAY - Mainly sunny / east winds 10-15 km/h / alpine high temperature near -21SUNDAY - Sunny / northeast winds, 10-20 km/h / alpine high temperature near -15

Avalanche Summary

A few natural wind slab avalanches size 1.5-2 on northwest aspects were reported on Wednesday.On Monday, size 1 natural and human triggered wind slab avalanches were reported on all aspects at treeline and in the alpine. On Saturday, numerous natural and explosives triggered storm slab avalanches to size 2-2.5 were reported on north and east aspects in the alpine and treeline. These avalanches were 50-100 cm deep.

Snowpack Summary

10-20 cm of new snow sits on previous wind slabs at upper elevations.Â In sheltered areas and below treeline, the new snow sits on facets (sugary snow) surface hoar (feathery crystals) and a crust on south facing slopes.There are potentially three weak layers of surface hoar in the top 100 cm of the snowpack.Â One is down 30-50 cm, another is down 40-80 cm and the last one is down 80-110 cm.Â These layers are most prominent between 1600-1900 m.The lower portion of the snowpack is considered generally strong.

Problems

Wind Slabs

Previous variable wind directions means that wind slabs may be found on all aspects. Up to 20 cm of new snow will likely be forming fresh wind slabs, and may make older wind slabs more difficult to detect.

If triggered, storm or wind slabs may step down to deeper layers resulting in large avalanches.Keep an eye out for reverse loading created by variable winds.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Two weak layers of surface hoar may be found 60-120 cm deep in the snowpack. They are most prominent between 1600-1900 m, and have been the culprit in recent large avalanches, particularly in openings such as cutblocks, gullies, and slide paths.

Be aware of the potential for wide propagation.Watch for signs of instability such as whumpfing, cracking, or recent avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 2.5

Valid until: Mar 1st, 2019 2:00PM