Avalanche Forecast

Issued: Apr 8th, 2016 8:02AM

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

pmarshall, Avalanche Canada

Purcells.

Spring conditions. Avalanche danger is expected to rise during the day with warming and solar radiation. Plan to retreat to cooler north-facing terrain if the snow surface is becoming moist or wet.

Summary

Confidence

High

Weather Forecast

SATURDAY: A mix of sun and cloud. The freezing level could drop to 1700 m overnight before rising to around 2300 m during the day. Northwesterly winds peak overnight and ease to light northerly during the day. SUNDAY: Mainly sunny. The freezing level shoots up again to 2500-2600 m and winds are light and variable. MONDAY: A mix of sun and cloud. The freezing level remains near 2600 m and winds are light.

Avalanche Summary

No new avalanches were reported in the region on Thursday, but I suspect at least some small (size 1-1.5) loose wet sluffs occurred on steep solar aspects on Thursday. The possibility of persistent slabs and cornice falls should increase if the snowpack does not refreeze overnight and temperatures remain high.

Snowpack Summary

Sunshine and soaring temperatures resulted in moist or wet snow on all aspects and elevations, except true-north slopes above around 2200 m. Temperatures did not cool much overnight on Thursday, which probably prevented a strong refreeze. This may be the case again heading into the weekend. A couple crusts could exist in the top 30-50 cm up to around 2000 m, particularly on solar aspects. The late February persistent weak layer is down 60-100 cm below the surface. This layer may be a concern in isolated terrain, but it will probably take a large trigger like a cornice fall or surface avalanche in motion to set it off. A moist/wet, isothermal, and rapidly melting snowpack exists on all aspects below around 1500 m.

Problems

Loose Wet

Loose wet activity should continue, particularly on solar aspects during the day.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornices could fail easily during the day when temperatures soar and the sun reappears.

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

Wet Slabs

Intense solar radiation, a heavy wet surface sluff, or a cornice fall could be enough to trigger lurking deep weaknesses creating a destructive wet slab.

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

Possible

Expected Size

3 - 6

Valid until: Apr 9th, 2016 2:00PM