Avalanche Forecast

Issued: Apr 5th, 2014 9:50AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs, Deep Persistent Slabs and Loose Dry.

swerner, Avalanche Canada

Northwest Inland.

Monday's storm could pack a punch and is driving the Danger Ratings.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Unsettled conditions bringing light precipitation amounts will persist through the weekend. Overnight Sunday an intense, direct frontal system will slam the North Coast bringing moderate precipitation amounts and rising freezing levels to Inland Regions.Sunday: Freezing levels rising to 1200 m and expecting 10 mm. Ridgetop winds strong from the south. Monday: Freezing levels rising to 1800 m and expecting up to 20 mm. Ridgetop winds strong from the south gusting to extreme values. Tuesday: Freezing levels falling to 1100 m or lower. Precipitation amounts 10 mm. Ridgetop winds moderate from the south.

Avalanche Summary

No recent avalanche activity has been reported. Last Tuesday a steep rocky NE facing feature at 1900m released naturally resulting in a size 3 avalanche. The possibility for large avalanches appears to be still there, and the chance of one is likely to increase with anticipated warming, and/ or localized new loads including precipitation and strong winds on Monday.

Snowpack Summary

Up to 20 cm new snow recently fell onto a variety of old snow surfaces consisting of surface hoar, small grained facets and melt freeze crusts. A poor bond likely exists.Previous snow that fell between March 27-30th fell on top of a variety of old snow surfaces. I suspect the ongoing melt freeze cycles have largely healed any instabilities associated with this interface. Below treeline a spring-like snowpack exists including melt-freeze crusts and possibly isothermal conditions. Two persistent weak interfaces exist deeper in the snowpack. The early March layer can be found down 75 - 100cm and is composed of facets/surface hoar on shady aspects and facets/crust on southerly aspects. The early February crust/facet/surface hoar combo is down 150 - 200cm. While it's been mostly dormant, I would not rule out the possibility of it reawakening if we see prolonged warming and/or intense sunshine.

Problems

Storm Slabs

New snow driven by strong ridge top winds has likely created touchy slabs at and above treeline. This snow is not expected to bond well to the current crust/surface hoar combo and will likely remain sensitive to natural avalanche activity.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stick to simple terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Deep Persistent Slabs

Two buried weak layers exist in the snowpack. These weak layers could be activated by cornice fall, a smaller surface avalanche in motion, or a rider finding the sweet spot, which would be most likely in steep rocky terrain. Warming is also a concern

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Loose Dry

Loose dry avalanches are likely from steep, rocky terrain features. Below treeline where surface snow may become moist due to rain and/ or warming smaller loose wet avalanches may occur.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Surface avalanches in motion may trigger deeper instabilities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Apr 6th, 2014 2:00PM