Avalanche Forecast

Issued: Apr 22nd, 2014 8:31AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

Peter, Avalanche Canada

Kootenay Boundary.

Avalanche danger can rise quickly with afternoon warming and solar radiation. Be aware of changing conditions and overhead hazards.For more insight into spring danger ratings, check out this blog post.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Wednesday: Cloudy with sunny breaks and scattered flurries (~5 cm). The freezing level is around 1500 m and ridge winds are moderate from the SW. Thursday: Mainly cloudy with showers or flurries 5-10 cm. The freezing level is around 1800 m and winds are light but gusty from the south. Friday: Mainly cloudy with showers or flurries. The freezing level is around 1800-2000 m and ridge winds are light from the S-SW.

Avalanche Summary

Expect loose wet avalanches in steep terrain if it is raining or during sunny periods, especially if the sun or rain is affecting fresh snow. New storm of wind slabs may develop in higher terrain if we see significant new snow accumulation. Make conservative terrain choices if you see 30 cm of new snow or more in 24-48 hours or significant loading from strong winds. There is still potential for deep persistent slabs to wake up. This is most likely during periods of heavy rain or warm temperatures and strong solar radiation. Your best bet is to pack it in when the snow surface is becoming really wet and mushy.

Snowpack Summary

This is a broad general summary of conditions in the region. This summary is based on very limited field data and should be supplemented with local observations to help assess avalanche danger. Over the past week or so we have seen moderate amounts of moist new snow mixed with showers or periods of rain below 1600-1800 m. Westerly winds have likely formed pockets of wind slab at higher elevations in lee of ridges and terrain features. The upper snowpack generally consists of layers of moist or wet snow mixed with several well bonded crusts. Most areas are likely below threshold for avalanches below 1300-1500 m depending on aspect. The late January/early February persistent weak layer is deeply buried but could still wake up during periods of heavy precipitation (especially rain) or significant warming and solar radiation. Be particularly wary of this on large open alpine slopes. Cornices are large in some areas and should be given a wide berth.

Problems

Wind Slabs

Fresh wind slabs could develop in exposed lee terrain and cross-loaded slopes near ridge top over the next several days. Stay alert to signs of recent wind loading.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

This problem is unlikely but should remain on the radar. We could see this wake up again with forecast warming, solar radiation and rain.

Be aware of the potential for large, deep avalanches due to the presence of buried persistent weak layers.>Use caution on big alpine slopes, especially around thin areas that may propagate to deeper instabilities.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Apr 23rd, 2014 2:00PM