Avalanche Forecast

Issued: Apr 27th, 2017 4:00PM

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

rupert wedgwood, Parks Canada

Jasper.

Pay close attention to freezing levels as we move into spring-like conditions. The avalanche danger will increase with rain, solar exposure and daytime heating.

Summary

Weather Forecast

With the Jet Stream to the South cool temps dominate to the weekend. Snowfall or rain will tapper off by Friday AM. With freezing levels descending to the valley bottomÂ snowpack overnight recovery will be good. Winds remaining light N to W. Daytime freezing levels will be close to 2,000m,

Snowpack Summary

On Northerly facing slopes above treeline up to 20 cm of loose new snow sits over a well consolidated upper snowpack. Melt freeze crusts are ubiquitous to treeline above which their distribution narrows to solar slopes up to 2600m. The mid-pack is consolidated and bridges the weak base. The bottom snowpack is a mix of weak facets and depth hoar.

Avalanche Summary

Avalanche activity will increase with thermal inputs such as rain, direct solar radiation and daytime warming. During the morning and after a good nights freeze the danger will gradually increase during the day. Typically it will be at it's greatest from 14:00. Likely trigger spots are from shallow rocks, cliffy terrain and shallow snowpack areas.

Confidence

Freezing levels are uncertain on Sunday

Problems

Loose Wet

Freezing overnight temperatures decrease the danger in the morning until it warms up increasing the hazard. Most widespread during the late afternoon on solar facing slopes. Sluffs from rocks can trigger large slides once the snow is wet.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Pay attention to sluffing off cliffs and steep solar terrain, signs of a warming snowpack.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Cornices

Cornice failures are still being noted periodically on West aspects 2500-2800m.

Avoid travel on slopes that are exposed to cornices overhead.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Deep Persistent Slabs

The deep instability is well bridged by a solid mid-pack; however, it could be triggered by a cornice failure.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

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