Avalanche Forecast

Issued: Mar 30th, 2017 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Storm Slabs and Deep Persistent Slabs.

jonas hoke, Parks Canada

Waterton Lakes.

Snowfall amounts for Friday are uncertain, exercise extra caution if forecast accumulations are exceeded.

Summary

Weather Forecast

Friday: Snowfall (10-15cm) in the AM (clearing trend in the PM). Ridgetop wind moderate N (trending light). Treeline temps, High -2, Low -6.Saturday: Partly cloudy, PM flurries. Ridgetop wind strong SW. Treeline temps, High -1, Low -4.Sunday: Parlty cloudy, AM flurries. Ridgetop wind mod-strong SW. Treeline temps, High -7, Low -10.

Snowpack Summary

Fresh storm slabs will form Friday with incoming snow and N winds. These will likely be touchy as they will overlie; a thin melt-freeze crust on all but north aspects above 2000m, scoured old crust in wind exposed terrain, and wind slab 10-40cm deep on N aspects. Treeline and above, the basal snowpack remains faceted and weak in many locations.

Avalanche Summary

A few small-large (up to size 2.0) wind slabs were observed on alpine N aspects Thursday. Several large to very large avalanches from last week and the week before suggest that deep persistent weaknesses in the snowpack will remain as a concern well in to the spring.

Confidence

Forecast snowfall amounts are uncertain

Problems

Wind Slabs

Wind slabs formed by SW winds on Thursday will be difficult to detect under Fridays new snow. Fresh wind slabs will likely form with SW winds forecast for the weekend.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Storm Slabs

Keep an eye out for reverse loading created by an upslope storm.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Deep Persistent Slabs

Facets in the bottom 1/3rd of the snowpack are persisting as a weak layer to be respected. These could be triggered by large triggers such as cornice falls and wind slab avalanches.

Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.Be wary of large alpine slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 4

Valid until: Apr 2nd, 2017 4:00PM