Avalanche Forecast

Issued: Mar 11th, 2018 3:38PM

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

mbender, Avalanche Canada

Sea To Sky.

Expect avalanche danger to increase as the temperature rises through the day. Danger ratings are rated for the heat of the day when the likelihood of triggering an avalanche is highest.

Summary

Confidence

Moderate - Freezing levels are uncertain on Monday

Weather Forecast

MONDAY: Mix of sun and cloud / Light to moderate southeast wind / Alpine temperature 4 / Freezing level 2500m TUESDAY: Mainly cloudy / moderate southeast wind / Alpine temperature 3 / Freezing level 2400m WEDNESDAY: Mainly cloudy with isolated flurries / light west wind / Alpine temperature -1 / Freezing level 1200m

Avalanche Summary

On Sunday there was a report of a skier triggered size 2 storm slab avalanche on a west aspect at 2400m. On Saturday there were several size 2.5 natural persistent slab avalanches reported. These were suspected to have run in the previous 24hours and were observed on northwest to east aspects between 1900 and 2000m. Additionally there have been several observations of skier triggered storm and wind slab avalanche size 1-2 mostly on northerly aspects between 1800 and 2000m. On Friday there were reports of a several explosives and naturally triggered storm slab avalanches size 1.5-2 on a variety of aspects that entrained the storm snow only.

Snowpack Summary

Recent new snow has settled and been redistributed by west and south winds. This new snow sits on a sun crust on steep south-facing slopes, cold dry snow on northerly aspects, and wind affected snow at upper elevations. The surface snow is reported to be moist on all aspects to 1800m and to mountain top on solar aspects.Last week's storms buried a weak layer composed of soft facets, surface hoar, and/or crust that is roughly 50-100 cm below the surface. This layer has produced whumpfing, sudden results in snowpack tests, and some remotely triggered avalanches. Lots of the activity has been on buried surface hoar on north aspects at upper treeline elevations. The snowpack is well settled and strong beneath this interface. Variable winds in the past month have produced cornices on many ridgelines. They will become touchier as they grow in size, as temperatures rise, and when they are subject to the strong late-winter sun on clear days.

Problems

Wind Slabs

Recent snow and southwest winds have built storm and wind slabs. Expect to see loose wet avalanches as the sun comes out and the freezing level rises.

Extra caution needed around cornices with current conditions.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Surface crusts will break down quickly with little overnight freeze. Expect to see sluffing from steep sun exposed terrain as the day warms up.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A layer of surface hoar, sugary facets, and/or crust is buried 50-100 cm deep and has produced widespread whumpfing, concerning snowpack test results, and a few large remotely triggered avalanches. Upper treeline elevations are the greatest concern.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection while travelling at treeline elevations.Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Mar 12th, 2018 2:00PM