Avalanche Forecast

Issued: Apr 7th, 2016 8:11AM

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

pmarshall, Avalanche Canada

South Columbia.

Plan to start and finish your day early while the weather is very warm and sunny. Minimize your exposure to large sunny slopes and overhead hazard.

Summary

Confidence

Moderate

Weather Forecast

FRIDAY: Mainly sunny. The freezing level remains close to 3500 m and winds could rise to moderate or strong from the W-SW late in the day. SATURDAY: A mix of sun and cloud. The freezing level could drop to 2000 m and winds are generally light from the NW. SUNDAY: A mix of sun and cloud. The freezing level shoots up again to 2500 m and winds are light and variable.

Avalanche Summary

I suspect sunshine and rapidly rising temperatures set off a widespread loose wet cycle on steep sun-exposed slopes on Thursday. Some areas may have seen cornices popping off and perhaps isolated slab avalanche activity. Friday will be a very similar day in terms of weather. We could see loose wet sluffing taper off a little, but the potential for persistent slabs and cornices falls could be even higher as the snowpack warms even more.

Snowpack Summary

Sunshine and soaring temperatures may have resulted in moist or wet snow on all aspects and elevations, except possibly very high true-north slopes. The existence and strength of a surface crust will be important on Friday. If a crust doesn't form or it breaks down really early, then avalanche danger might stay elevated for the entire day. A couple crusts could exist in the top 60-80 cm up to around 2000 m. We could see loose wet snow sliding on the upper crust with the potential for wet slabs running on deeper crusts. The late February persistent weak layer is down 80 to 120 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.

Problems

Loose Wet

Watch for loose wet sluffing in steep sun-exposed terrain during the day.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Cornices could fail easily during the day thanks to soaring temperatures and strong sunshine.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Persistent Slabs

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

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

Possible

Expected Size

3 - 6

Valid until: Apr 8th, 2016 2:00PM