Avalanche Forecast

Issued: Mar 22nd, 2019 3:20PM

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

mconlan, Avalanche Canada

Purcells.

Seasonal weather returns. Travel conservatively and with a sense of caution, as buried weak layers may persist in the snowpack.

Summary

Confidence

High -

Weather Forecast

FRIDAY NIGHT: Increasing clouds, light southwest wind, freezing level 2300 m.SATURDAY: Mostly cloudy with intermittent snow in the alpine and rain below, trace accumulation, light southwest wind, alpine temperature -3 C, freezing level 1800 m.SUNDAY: Cloudy with snowfall, accumulation 5 cm, light east wind, alpine temperature -2 C, freezing level 1900 m.MONDAY: Cloudy with light snowfall, accumulation 1 to 3 cm, light southwest wind, alpine temperature -3 C, freezing level 1800 m.

Avalanche Summary

Many wet loose avalanches were observed between Sunday and Thursday. They were large (up to size 3), occurred mostly on southeast to southwest aspects, and at all elevations. Many of these avalanches scoured to basal weaknesses. A notable deep persistent slab avalanche released on Wednesday, likely triggered by a cornice fall. It was 100 cm deep on a northeast aspect at 2900 m.The wet avalanche cycle will diminish over the weekend as cooler and cloudier weather prevails.

Snowpack Summary

Below around 1800 m, the snow surface should remain wet on all aspects due to rain this weekend. Above around 1800 m, the weekend's precipitation should fall as snow. The snow will overly a melt-freeze crust on all aspects up to 2000 m and to ridgetop on sun-exposed slopes. The new snow will fall onto previously dry snow and potentially surface hoar crystals on northerly aspects above 2000 m.A few weak layers may still exist in the snowpack. A layer of faceted grains may be found 20 to 30 cm deep. It could be most problematic when in combination with hard wind-affected snow, which has been found on northerly aspects above 2000 m. Another layer of faceted grains and/or surface hoar may be found around 50 to 90 cm deep, also with a melt-freeze crust on southerly aspects. These layers haven't produced avalanches recently, but professionals are tracking them, as they have been reactive in some snowpack tests.The base of the snowpack is composed of weak faceted snow, which may be associated with a melt-freeze crust. Although this layer has been dormant for a while now, there were recent reports of a few sporadic avalanches on this layer, suggesting that it could still be triggered.

Problems

Persistent Slabs

A few weak layers still exist within the snowpack at a depth that is prime for human triggering. The recent hot weather may have influenced these layers, but time is needed to assess how much they have changed.

Best to avoid thin, rocky terrain, where it may be easier to trigger deeper weak layers.Back off if you encounter whumpfing, hollow sounds, or shooting cracks.Avalanche hazard may have improved, but be mindful that buried instabilities are still present.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Loose Wet

Although the freezing level is dropping, it will likely still be high enough to keep the snowpack wet at lower elevations. Rain may further wet the snow, increasing the potential for loose wet avalanches.

Avoid exposure to terrain traps, where the consequences of a small avalanche could be serious.Use extra caution on slopes if the snow is moist or wet.Avoid exposure to areas with overhead hazard during periods of rain.

Aspects: All aspects.

Elevations: Below Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 23rd, 2019 2:00PM