Avalanche Forecast

Issued: Mar 21st, 2019 4:26PM

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

mconlan, Avalanche Canada

South Columbia.

The hot and sunny weather persists on Friday. The danger will be the highest when the day heats up. Set up your plan to avoid sun-exposed slopes and overhead exposure during the heat of the day.

Summary

Confidence

High -

Weather Forecast

THURSDAY NIGHT: Clear skies, light south wind, alpine temperature 5 C, freezing level 3000 m.FRIDAY: Clear skies, light south wind, alpine temperature 4 C, freezing level 2700 m.SATURDAY: Cloudy with light snow in the high alpine and rain below, accumulation 1 to 3 cm, light west wind, alpine temperature 0 C, freezing level 1900 m.SUNDAY: Cloudy with snowfall, accumulation 5 cm, light southeast wind, alpine temperature -3 C, freezing level 1800 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 few slab avalanches were also triggered naturally, by skiers, and large machines. They occurred on all aspects and generally at treeline and alpine terrain. This avalanche cycle may continue on Friday on sun-exposed slopes, as temperatures remain exceptionally warm and the sun shines strong. The cycle should 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 1800 m on northerly aspects. The upper 30 to 60 cm of snow may slide easily during the day on sun-exposed slopes, either as loose wet snow or as a cohesive slab, as this snow sits over weak faceted grains or a melt-freeze crust. The wet snow may freeze into a melt-freeze crust overnight.Below treeline, a weak layer of faceted grains and/or feathery surface hoar crystals may be found around 60 to 120 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 lower snowpack is generally consolidated and strong. The exception is around thin, rocky areas in the alpine, where the snowpack is composed of faceted snow. The warm air and sunny skies could trigger very large avalanches that could run to the valley bottom.

Problems

Loose Wet

The upper snowpack will likely destabilize in the day with hot and sunny weather, producing loose wet avalanches. The most problematic time is with maximum warming during afternoon hours. Best to avoid sun-exposed slopes during the heat of the day.

Avoid sun-exposed slopes and overhead exposure during the afternoon heat.Cornices are large and looming and could trigger avalanches on slopes below them.Use extra caution on slopes if the snow is moist or wet.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Persistent Slabs

A slab of snow may be poorly bonded to weak, sugary faceted snow or a melt-freeze crust. The warm temperature and strong sun has increased the likelihood of triggering a slab avalanche by humans, cornices, and naturally.

Stay well-back from corniced ridges; they are weak and could trigger persistent slab avalanches.Loose wet avalanches may trigger persistent slab avalanches as the day heats up.Best to avoid thin, rocky terrain, where it may be easier to trigger deeper weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

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