Avalanche Forecast

Issued: Apr 7th, 2015 10:40AM

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

ghelgeson, Avalanche Canada

South Columbia.

Stay alert to conditions that change with aspect, elevation and time of day. Watch for clues like a moist or wet snow surface that indicate its time to find colder snow or head for home.

Summary

Confidence

Fair

Weather Forecast

WEDNESDAY: Freezing level starting at 900m, rising to 2000m. Light N/NE winds at all elevations. No significant precipitation expected. Mostly clear skies.THURSDAY: Freezing level starting at 1200m, rising to 2200m. Light W/SW winds at all elevations. No significant precipitation expected. Clear skies.FRIDAY: Freezing level holding at 1900m. Moderate S/SW winds at treeline, strong S/SW winds at ridgetop. No significant precipitation expected. Cloud cover rapidly building to overcast by lunch.

Avalanche Summary

On Monday a bit of small loose wet activity was observed. Sunday's observations were limited to power sluffing in steep high elevation terrain.

Snowpack Summary

Surface faceting is beginning to work on the 15 to 45 cm generated by convective snow fall over the weekend. This snow remains dry on high elevation north facing features, but is moist almost everywhere else. Just below this snow you'll find tired old wind slabs at upper elevations and the supportive late-March crust that is thought to exist up to around 2100m. Moist snow underneath the late-March crust is ubiquitous in most of the region.Two significant persistent weak layers composed of crust and facets exist in the snowpack. Mid-March is down 40 to 80cm below the surface and Mid-February is down 80 to 140cm. Observations indicate that there is significant faceting occurring between the two crusts. While avalanche activity on these weak layers has tapered off snowpack tests indicate that these layers may still be sensitive to triggering.

Problems

Cornices

Steadily increasing temperatures over the latter half of the week will make cornices more prone to failure. While falling cornice is in itself problematic, this action could drive persistent slab release on slopes below.

When traveling in the alpine, be SURE you're on the ridge, and not on a cornice.>Cornices become weak with daytime heating so you need to travel early on exposed slopes.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 5

Loose Wet

Anytime previously dry/cool snow experiences the intense kiss of the spring sun, loose wet avalanches are likely. Increasing temperatures may even drive loose wet activity on high elevation north and east facing features as the week goes on.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

While the likelihood of triggering a large persistent slab avalanche has gone down, the consequences of human triggering remain high. It's tough to say which features harbor a trigger-able weakness and which don't with any amount of certainty.

Stick to well supported terrain while avoiding potential trouble areas like rock outcroppings, convexities, and spots where the snowpack goes from thick to thin.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 8th, 2015 2:00PM