North Rockies Avalanche Forecast

Issued: Apr 12th, 2021 4:00PM

Tue Apr 13th Current Conditions
Alpine Considerable Treeline Considerable Below Treeline Considerable
Wed Apr 14th 2 Day Outlook
Alpine Considerable Treeline Considerable Below Treeline Considerable
Thu Apr 15th 3 Day Outlook
Alpine Considerable Treeline Considerable Below Treeline Considerable

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

A prolonged warming trend will increase the likelihood of avalanche activity. Danger rating is for peak daytime warming. Check out this blog for further information on the influence of warming and how to manage it.

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

MONDAY NIGHT: Clear skies, 10 km/h southwest wind, alpine temperature -4 C, freezing level near valley bottom.

TUESDAY: Clear skies, 10 to 20 km/h southwest wind, alpine temperature -1 C, freezing level rising to 1900 m.

WEDNESDAY: Clear skies, 10 km/h northwest wind, alpine temperature 3 C, freezing level near valley-bottom in the morning and rising to 2700 m.

THURSDAY: Clear skies, 20 km/h east wind, alpine temperature 5 C, freezing level 3000 m.

Avalanche Summary

A few small to large loose wet and wind slab avalanches were observed in the region on Sunday on sun-exposed slopes. A few large avalanches were also observed on north aspects out of alpine terrain in the south of the region.

Looking forward, avalanche activity is expected to spike during periods of daytime warming and quiet down as the night cools the region.

Snowpack Summary

Warm air and sunny skies are moistening the snow surface, at least up to around 1900 m and to the mountain tops on sun-exposed slopes during daytime warming, with a hard crust expected overnight and early-morning. On north aspects above 1900 m, 20 to 40 cm of recent dry snow likely prevails, which may have old wind slabs. Cornices are very large along many ridgelines.

The warming trend has the potential of reactivating deeper weak layers, including a layer from mid-February as well as basal layers in shallow, rocky terrain along the eastern slopes of the Rockies.

Terrain and Travel

  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.

Problems

Cornices

An icon showing Cornices

Likelihood

Possible-Likely

Expected Size

2 - 3

Cornices are large and will weaken with daytime warming. Stay well back from them on ridges and avoid travelling beneath them. A cornice fall has the potential of triggering slabs on the slopes below.

Aspects:

North, North East, East, North West.

Elevations:

Alpine.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely

Expected Size

1 - 2

The snow surface will weaken over the course of the day as warm air and sunny skies prevail. The most likely areas to get into trouble are above terrain traps.

Aspects:

All aspects.

Elevations:

All elevations.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible

Expected Size

2.5 - 3.5

A prolonged period of warm air and sunny skies will start to warm the snowpack, increasing the likelihood of reactivating buried weak layers. It is uncertain if and when large slab avalanches may release, but the possibility remains during this warm period. The most likely areas for deeper releases include rocky and thin snowpack areas.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Apr 14th, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.