Archived

Avalanche Forecast

Mar 4th, 2021–Mar 7th, 2021

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Waterton Lakes.

http://www.pc.gc.ca/apps/links/goto_e.asp?destination=

UPDATED THUSDAY 08:00

This is the first big warm up of the season, and we expect to see an increase in natural avalanche activity, especially on sunny slopes - the hazard will likely creep into the HIGH range on Thursday afternoon with intense sun.

Weather Forecast

Thursday: Sunny. Alpine temperature: High 3 C. Ridge wind southwest: 20-40 km/h. Freezing level: 2600 meters dropping to 1300m overnight with a weak inversion.

Friday: Repeat of Thursday with a little more cloud cover.

Saturday: Flurries. Ridge wind southwest: 30 km/h gusting to 60 km/h. Freezing level: 2500 metres.

Snowpack Summary

Surface snow will quickly become moist as the sun beats down and freezing levels rise to ridge top. 20-50cm wind slab sits on top of the weak February 14 facet layer which is above a melt freeze crust at treeline and below. The remainder of the midpack is made up of dense facets and decomposing crusts, with early season ice crusts forming the base.

Avalanche Summary

Several natural wind slab and loose wet avalanches were observed on Wednesday on SE through NE aspects from 1800-2200m with rising freezing levels. Expect this trend of natural avalanches to continue until temperatures drop.

Confidence

The weather pattern is stable

Avalanche Problems

Persistent Slabs

This problem is most prevalent at and below treeline, and will become easier to trigger with the warm temperatures. An avalanche on this layer will have heavy consequences with a burial depth of 20-50cm and the potential for wide propagation.

Be aware of the potential for wide propagations.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 3

Loose Wet

Rising freezing levels will make wet loose avalanches a major concern. Be mindful of your overhead hazard be aware that warm temperatures may cause cornices to fail.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.
Minimize exposure when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Wind Slabs

Older wind slabs will become more reactive throughout the day as temperatures increase. Be especially wary of sunny lee slopes.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Avoid avalanche terrain during periods of strong sun.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2