Avalanche Forecast

Issued: Apr 4th, 2016 8:18AM

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

pmarshall, Avalanche Canada

Purcells.

Cloud and slight cooling should help temporarily drop avalanche danger on Tuesday, but continue to exercise caution if the sun appears during the day.

Summary

Confidence

Moderate

Weather Forecast

TUESDAY: Mainly cloudy with a chance of showers/flurries and afternoon sunny breaks. The freezing level dips to around 1400 m overnight and rises to 1600-1800 m during the day. Winds are moderate to strong from the W-NW. WEDNESDAY: Clearing. The freezing climbs to 2600 m and winds are light to moderate from the West. THURSDAY: Mainly sunny. The freezing level continues its ascent up to 3200 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 this week.

Snowpack Summary

Recent warm temperatures, weak/non-existent overnight refreeze, and rain have moistened the upper snowpack at all elevations. Elevations above 2000 m may getting snow on Monday (5-10 cm is possible), and a cooling trend could create a crust at or near the surface down to around 1500 m. Below 1400 m, the snowpack is likely fully isothermal. The March 22nd rain crust is present to around 2000 m, but the warm temps have likely allowed the overlying 30 to 40 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 40 to 100 cm below the surface, and may

Problems

Loose Wet

A bit of fresh snow and a chance of sunny breaks could lead to renewed loose wet activity on sun-exposed slopes.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

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

3 - 6

Persistent Slabs

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

A few different buried persistent weak layers (PWL's) are 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