Avalanche Forecast

Issued: Apr 20th, 2014 8:57AM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Resist the urge to rely on danger ratings alone. Conditions change rapidly at this time of year and you need to stay tuned in to local conditions.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Monday: A mix of sun and cloud becoming overcast in the afternoon with light flurries / Moderate southerly winds / Freezing level at about 2000mTuesday: 10-20cm of wet snowfall at higher elevations / Moderate southerly winds / Freezing levels are uncertain, although some models are indicating up to 2500mWednesday: Mainly overcast skies with light flurries / Moderate southerly winds / Freezing level at about 1800m

Avalanche Summary

In Kootenay Pass on Saturday there was a loose wet avalanche cycle to size 1.5 on steep, sun-exposed terrain. We also received a report of a skier triggered size 1.5 loose wet avalanche close to Nelson.

Snowpack Summary

Note: We have very little recent data to base this summary on. If you're out in the mountains ask other locals about the current conditions and spend some time making snow and weather observations to help assess local hazard. Up to 15cm of new snow is estimated to have fallen at upper elevations on Saturday night. Below about 1600 m rain continued to saturate the snowpack. Generally moderate westerly winds have shifted the new accumulations into wind slabs in lee upper elevation terrain. Although the new snow is expected to stabilize quickly with Sunday's warm temperatures, I'd be cautious in the immediate lee of high elevation terrain breaks and ridge crests. Warm temperatures and solar radiation have created moist surfaces in many other areas. If there is a good overnight freeze these surfaces will exist as a harder crust.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. Cornices are large in some areas and should be given a wide berth.

Problems

Wind Slabs

Snow and wind on Saturday night has added to an ongoing wind slab problem. Wind slabs are expected to stabilize quickly although human triggering is still possible in high elevation start zones.

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

Expected Size

1 - 2

Loose Wet

Forecast sunny breaks and warming on Monday will promote pushy loose wet avalanche activity. Watch for increased reactivity in areas where new snow is exposed to solar radiation for the first time.

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.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

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 21st, 2014 2:00PM