Avalanche Forecast

Issued: Apr 8th, 2015 10:13AM

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

ghelgeson, Avalanche Canada

South Columbia.

Direct sun & warmth are currently the primary drivers of hazard and the weather forecast indicates that Thursday will be quite warm. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.

Summary

Confidence

Fair

Weather Forecast

THURSDAY: Freezing level starting at 1200m, rising to 2200m. Light W/NW winds at all elevations. No significant precipitation expected. Clear skies.FRIDAY: Freezing level holding at 1800m. Moderate S/SW winds at treeline, strong S/SW winds at ridge-top. No significant precipitation expected. Cloud cover rapidly building to overcast by lunch.SATURDAY: Freezing level hovering around 1500m. 2 to 8mm precipitation, 2 to 15cm of snow possible. Moderate SW winds at treeline, strong SW winds at ridge-top.

Avalanche Summary

Observations from Sunday, Monday and Tuesday were limited to power sluffing from steep high elevation terrain and small loose wet activity.

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

Thursday looks to be the warmest day in recent memory. As the mercury rises cornices become more prone to failure. While falling cornice is in itself problematic, this mechanism could drive persistent slab release on slopes below.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 5

Loose Wet

Loose avalanche activity should peak Thursday as the freezing level creeps well into the alpine. Loose wet avalanches are possible on all aspects. While slow moving, these avalanches can be very powerful and you do not want to be caught by one.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

It's tough to say which features harbor a trigger-able weakness and which don't with any amount of certainty, but cornice fall driven by warm temperatures is the most likely trigger.

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.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Apr 9th, 2015 2:00PM