Avalanche Forecast

Issued: Apr 4th, 2016 8:21AM

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

pmarshall, Avalanche Canada

Cariboos.

Fresh snow, and potentially a fresh wind slab problem, await you if you manage to get up high in the mountains on Tuesday. However, this brief change gives way to another heat wave later in the week.

Summary

Confidence

Moderate

Weather Forecast

TUESDAY: Mainly cloudy with a chance of showers/flurries in the afternoon. The freezing level dips to around 1400 m overnight and rises to 1500-1600 m during the day. Winds are moderate to strong from the West. WEDNESDAY: Flurries/showers early, then clearing. The freezing climbs to 2500 m and winds are light to moderate from the West. THURSDAY: Mainly sunny. The freezing level continues its ascent up to 3000 m. Winds should ease to light and variable.

Avalanche Summary

Recent soaring temperatures and strong sunshine have resulted in significant natural avalanche activity for the past several days. Slab avalanches to size 2.5 have been very common over the last few days on almost all aspects (the exception being high elevation north). Large loose wet avalanches and cornice falls have also been a common theme. Cloud cover and slight cooling might halt natural activity briefly on Tuesday.

Snowpack Summary

Recent warm temperatures, weak/non-existent overnight refreeze, and rain have moistened the upper snowpack at all elevations. Slopes above 1800-2000 m could have a healthy dusting of snow (up to 15 cm) by Tuesday morning, with the possibility of fresh winds slabs in exposed lee terrain. Below 1400 m, the snowpack is likely fully isothermal. The March 20th rain crust is present to around 2000 m, but the warm temps have likely allowed the overlying 30 to 50 cm of snow to bond well. Once it freezes, this layer should not be much of a concern. The late February persistent weak layer is now down 80 to 160 cm below the surface. While it may be a concern in isolated terrain, it would probably take a large trigger like a cornice fall or surface avalanche in motion to provoke it.

Problems

Wind Slabs

New snow and strong winds on Monday could combine to build fresh and touchy wind slabs in exposed leeward terrain. Expect any new snow to sluff off easily if the sun pokes out at all.

Be alert to conditions that change with elevation.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Cooler temperatures and more cloud might make cornices less likely to fail naturally, but I would still give droopy overhanging cornices a wide berth.

Do your best to avoid traveling on or underneath cornices. If you have to, move quickly and only expose one person at a time.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

Brief and slight cooling on Tuesday could make this problem less sensitive to triggering, but keep this on your radar for later in the week when the heat and sun return.

A buried persistent weak layer (PWL) is lurking in our snowpack which means there is potential for large destructive avalanches that have the capability to run full path.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 5th, 2016 2:00PM