Avalanche Forecast

Issued: Mar 15th, 2019 5:14PM

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

jsmith, Avalanche Canada

South Columbia.

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; intense solar radiation will increase the likelihood of human triggered avalanches.

Summary

Confidence

Moderate -

Weather Forecast

FRIDAY NIGHT: Partly cloudy with some clearing / Light, westerly winds / Alpine low -5 / Freezing level below valley bottom.SATURDAY: Partly cloudy in morning becoming mostly sunny / Light, westerly winds / Alpine high 3 / Freezing level rising to 1800 m.SUNDAY: Sunny / Light, northwesterly winds / Alpine high 5 / Freezing level rising to 2200 m.MONDAY: Sunny / Light, northwesterly winds / Alpine high 7 / Freezing level rapidly rising to 2700 m.

Avalanche Summary

On Thursday, two rider triggered persistent slab avalanches up to size 2 were reported on northerly aspects at treeline and below treeline. Additionally, a cornice failure triggered a size 2.5 persistent slab on a northeast facing treeline ridgetop.On Wednesday, numerous natural storm slab avalanches up to size 3 and rider triggered up to size 2 were reported on primarily solar aspects at treeline and above. Some of the avalanches were triggered remotely from lower angle terrain by skiers 50 m. away from the slope that avalanched. This suggests that recent storm snow is still very sensitive to human triggers in specific locations.

Snowpack Summary

10-15 cm of new snow brings the recent storm snow to 30-60 cm. This snow is sitting on a pile of facets (sugary snow), as well as a crust on sun exposed slopes. The recent storm snow has settled into a cohesive slab and is ripe for human triggering. This persistent slab is currently our primary concern.At lower elevations, a weak layer of surface hoar (weak, feathery crystals) buried in mid-January can be found approximately 60-120 cm deep. This layer has recently been unreactive, however, the forecast warming event may awaken this layer in low elevation areas such as steep cutblocks and large open glades.The lower snowpack is generally considered to be strong, except for shallow, rocky areas in the alpine.

Problems

Persistent Slabs

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; especially at treeline and above.

Avoid convex slopes on rocky terrain with a variable snow depth.Use extra caution on solar aspects where the new snow is sitting on a crust.Avoid steep terrain where the snow feels moist or slabby.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Loose Wet

Pin-wheeling snow below cliffs is a common sign that loose wet avalanches are becoming more likely.

Reduce exposure to over-head hazards such a large cornices during periods of strong solar radiation.Avoid steep, sun exposed slopes when the solar radiation is strong.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: East, South East, South, South West, West.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Mar 16th, 2019 2:00PM