Avalanche Forecast

Issued: Mar 21st, 2019 4:33PM

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

Avalanche Canada mconlan, Avalanche Canada

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The hot and sunny weather persists on Friday, which will likely continue the avalanche cycle on sunny slopes. The danger will be the highest when the day heats up, so make sure you are out of avalanche terrain early and with no overhead exposure.

Summary

Confidence

High -

Weather Forecast

THURSDAY NIGHT: Clear skies, light southwest wind, alpine temperature 4 C, freezing level 3000 m.FRIDAY: Clear skies, light southeast wind, alpine temperature 4 C, freezing level 3000 m.SATURDAY: Cloudy with light snow in the high alpine and rain below, accumulation 1 to 3 cm, light southwest wind, alpine temperature 0 C, freezing level 2200 m.SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm, light southeast wind, alpine temperature -3 C, freezing level 1700 m.

Avalanche Summary

Many wet loose avalanches were observed between Sunday and Wednesday. They were large (up to size 3), occurred mostly on southeast to southwest aspects, and at all elevations. A notable persistent deep slab avalanche was also triggered on Wednesday, likely from a cornice fall. It was 100 cm deep on a northeast aspect at 2900 m.This avalanche cycle is expected to continue on Friday, as temperatures remain exceptionally warm and the sun shines strong. The cycle may end on Saturday, as freezing levels drop and cloudy skies prevail.

Snowpack Summary

The warm air and sunny skies have produced wet snow to ridge top on southerly aspects and up to around 2100 m on northerly aspects. The upper 20 to 30 cm of snow may slide easily during the day, either as loose wet snow or as a cohesive slab, as it sits over weak faceted grains or a melt-freeze crust. The wet snow may freeze into a melt-freeze crust overnight.A weak layer of faceted grains and/or feathery surface hoar crystals buried in mid-January may be found around 50 to 90 cm deep. Although this layer has been dormant for a few weeks, the current warm conditions may awaken this layer. Steep cutblocks and large open glades at lower elevations are the most likely places to trigger this layer.The base of the snowpack is composed of weak faceted snow, which may be associated with a melt-freeze crust. The warm air and sunny skies has increased the likelihood of triggering very large avalanches on this layer.

Problems

Loose Wet

An icon showing Loose Wet
The upper snowpack is destabilizing in the day with hot and sunny weather, producing large avalanches. The most problematic time is with maximum warming during afternoon hours. Best to avoid avalanche terrain on or beneath southerly aspects.
Cornices are large and looming and could trigger avalanches on slopes below them.Avoid avalanche terrain during the afternoon heat, particularly on sun-exposed slopes.Constantly look up: stay well-away from overhead exposure, as avalanches could run full-path.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
As the warming continues, the likelihood of triggering deeper weak layers rises. Best to avoid avalanche terrain during the heat of the day.
Avalanches could reach valley bottom; avoid overhead exposure, especially on south aspects.Stay well-back from corniced ridges; they are weak and could trigger persistent slab avalanches.Best to avoid thin, rocky terrain, where it may be easier to trigger deeper weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Mar 22nd, 2019 2:00PM