Avalanche Forecast

Issued: Apr 21st, 2014 8:50AM

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

Peter, Avalanche Canada

South Rockies.

This bulletin was issued using very limited field data. Please send your observations to forecaster@avalanche.ca.Check out this video and blog post for more insight into managing spring conditions.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Tuesday: Cloudy with sunny breaks and showers â€“ around 5 mm. The freezing level is around 2600 m. Ridge winds are light to moderate from the S-SE. Wednesday: Cloudy with sunny breaks and scattered flurries or flurries. The freezing level is around 1800 m and ridge winds are moderate and gusty from the W-SW. Thursday: Mainly cloudy with showers or flurries developing. The freezing level is around 2200 m and winds are light but gusty from the south.

Avalanche Summary

Warm temperatures and sunshine have probably resulting in some loose wet avalanche activity, primarily from solar aspects. Isolated cornice collapses are also likely. We have not received any reports of deeper slab avalanches but I would not rule these out, especially considering the weather of the past couple days.

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. Prior to the weekend the region received up to 40cm of new snow with the snow line hovering between 1500 and 1700 m. This recent snowfall overlies a melt-freeze crust in many areas. My best guess is that cold wintery snow still exists in high, north facing terrain while warm temperatures and solar radiation have created moist surfaces everywhere else. If there is a good overnight freeze these surfaces will exist as a hard crust.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 during sunny periods. Any activity at this interface would be large and destructive. Also, give large sagging cornices a wide berth when traveling on or below corniced ridges.

Problems

Cornices

Large cornices loom above many alpine slopes and will become weak with daytime warming. Give cornices a wide berth while traveling on or below ridges.

Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating, so travel early on exposed slopes.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

The potential for deep persistent slabs will increase when the sun is shining, temperatures are warm or when rain falls. Minimize exposure to big alpine slopes when things are warming up.

Be aware of the potential for large, deep avalanches due to the presence of buried persistent weak layers.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely

Expected Size

3 - 6

Loose Wet

Loose wet activity is likely in steep terrain during periods of rain, warming, or solar radiation.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 22nd, 2014 2:00PM