Avalanche Forecast

Issued: Apr 13th, 2014 9:22AM

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

slemieux, Avalanche Canada

South Rockies.

Avalanche danger can rise very quickly with warming and solar radiation. Be aware of changing conditions and overhead hazards. Terrain choices and timing can be critical.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Tonight and Monday: The ridge of high pressure bringing clear and warm conditions remains over the province. Clouds will start building as a low pressure system approaches later in the day. Expect freezing levels to be near 2500 m and light to moderate North West winds.Tuesday: A trace of precipitation is forecasted with light North West winds, freezing levels going from 1200 m at night and rising to 1500 m during the day. Wednesday: Mainly cloudy, a possibility of light precipitation, freezing levels around 1700 m.

Avalanche Summary

Natural loose dry avalanches up to size 2 were reported in Waterton Lakes area. These would have initiated in the new snow sluffing on the underlying crust on shaded aspects in the alpine. Small wet loose avalanches were also reported on the solar aspects in the same region.

Snowpack Summary

Yesterdays light accumulation (~15 cm) is sitting on a crust in most places. Todays above freezing temperatures up to ~2000 m and intense solar radiation would have contributed to the creation of another melt-freeze crust on all aspects below this elevation and higher up on solar aspects. Snow stability is expected to decrease as the day progresses tomorrow, weakening the fresh windslabs and cornices in the alpine. The deep facet/crust persistent weakness buried at the beginning of February (now down up to 80-100 cm) should stay on your radar, especially on all alpine slopes that will see the intense sun tomorrow. Any activity at this interface would be large and destructive.

Problems

Loose Wet

Periods of intense solar radiation or pronounced warming could result in some loose wet activity, especially on steep slopes.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Daytime heating makes cornices droop and become unstable. Also, if anything is still able to trigger a deep persistent weak layer, it's a cornice release.

Give cornices a wide berth when travelling on or below ridges.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Deep Persistent Slabs

The forecasted intense solar and warm temperatures could trigger the deeply buried weak layer especially on the slopes that have not seen such a heat shock yet.

Be aware of the potential for very large avalanches due to the presence of a deep persistent weak layer.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Apr 14th, 2014 2:00PM