Avalanche Forecast

Issued: Apr 27th, 2017 5:37PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Summary

Weather Forecast

Continued convective flurries forecast for Friday with freezing levels rising to 2200 m. If the sun comes out expect temperatures to rise significantly. A weak ridge is moving in Friday night and Saturday should see drier and sunnier conditions.

Snowpack Summary

Convective showers today has added another 5-10 cm of storm snow. There are a variety of melt freeze crusts in the upper snow pack in all aspects and elevations except due north above 2300 m. There is a basal weakness at the bottom of the pack. It currently is only reactive to large triggers like cornices but may wake up with solar warming

Avalanche Summary

Several loose wet avalanches up to size 2.5 were reported today on south and west aspects. There were also some loose dry avalanches running out or steep north facing alpine terrain.

Confidence

Problems

Loose Wet

Brief solar input's or warmer then anticipated temperatures will rapidly moisten the new snow.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Pay attention to sluffing off cliffs and steep solar terrain, signs of a warming snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The snowpack is gaining strength, but the weak basal facets continue to produce sudden collapse results and can produce large avalanches with large triggers or heat. Stick to planar, supported slopes with a deeper snowpack when entering steep terrain

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Cornices

Cornices continue to fail. Minimize your time underneath these and remember that a cornice failure could also trigger the deep persistent slab on the basal facets.

Cornices become weak with daytime heating, so travel early on exposed slopes.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 28th, 2017 4:00PM