Avalanche Forecast

Issued: Apr 29th, 2017 4:00PM

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, Cornices and Deep Persistent Slabs.

A.L. Horton, Parks Canada

Jasper.

Spring conditions are here and fine skiing can be found at all elevations. Pay close attention to the freezing levels and plan to finish your day before the melt freeze crust breaks down and the afternoon avalanche cycle starts.

Summary

Weather Forecast

Cool, unsettled conditions will dominate through the weekend with isolated convective storms possible on Sunday.Â Freezing levels are expected to hover around 1700 m overnight resulting in poor recovery on Sunday morning.

Snowpack Summary

Winter conditions exist in the high alpine on Northerly slopes with up to 20 cm of loose new snow sitting over a well consolidated upper snowpack. Spring conditions exist on all other aspects and elevations with a melt freeze crust that is dependent on overnight freezing conditions.Â The snowpack is moist to wet snow to ground below this crust..Â

Avalanche Summary

Avalanche activity will increase after warm nights and/or with thermal inputs such as rain, solar radiation and daytime warming. The avalanche danger will be lowest after cold nights and strong crust formation and will increase into the afternoon and evening before sunset. Likely trigger spots are rocks, cliffy terrain and shallow snowpack areas.

Confidence

Problems

Loose Wet

Freezing overnight temperatures decrease this danger in the morning, it increases with daytime heating, sun and rain. 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: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Cornice failures are more likely with warm alpine temperatures.

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. This problem will transition to wet slabs as the snowpack warms this spring.

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 30th, 2017 4:00PM