Archived

Avalanche Forecast

Apr 15th, 2017–Apr 18th, 2017

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

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

1: Low

The avalanche danger rating in the alpine will be low

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Waterton Lakes.

Sun will be the main driver of avalanche danger. Be cautious of steep sunny slopes, or of exposure to cornices that may be sneakily catching sun from behind.

Weather Forecast

Sunday: Mainly Sunny. Westerlies easing to Calm. Freezing Level rising to 2000m. Treeline Low -6.5, High -1.Monday: Mainly cloudy. Light Westerlies/light flurries developing. Freezing Level 2200m. Treeline Low -1, High 0.5Tuesday: Cloudy, light flurries. Moderate Westerly winds. Freezing Level 2200m. Treeline Low -2, High 0.5.

Snowpack Summary

15cm of storm snow has trickled in over three days, creating storm slab pockets on slopes immediate lee to accompanying Strong SW winds. These sit on a widespread crust that formed after warm temperatures one week ago. Beneath is a well settled spring snowpack; however, facets still make up the bottom of the snowpack in some high Alpine areas.

Avalanche Summary

On Saturday, a recent cornice fall avalanche from an Alpine ridge was observed, which had triggered a small storm slab from a steep, unsupported lee slope. (This amounted to a Small avalanche - Size 1.5) On Friday, Numerous Small, Loose Wet avalanches occurred, as rain soaked fresh new snow that sat on a crust.

Confidence

Timing or intensity of solar radiation is uncertain on Monday

Avalanche Problems

Storm Slabs

Storm Slab pockets exist lee to West and SW winds, especially immediately behind ridge crests, outcrops, and islands of trees ("immediate lees"). It is possible a person or solar radiation could trigger these. This problem will lessen over time.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Cornices growth has continued. Periods of intense solar radiation will increase the chance of these failing naturally. Of course, they are most likely to break if walked upon.

Give cornices a wide berth when traveling on ridges.Do not travel on slopes that are exposed to cornices overhead.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

Loose Wet avalanches are possible on steep slopes on SUNDAY, as strong April Sun warms recent, soft surface snow. Expect this to be most pronounced were the most new snow lies: Easterly aspects/upper elevations in the Western portions of the park.

Use extra caution on solar slopes or if the snow is moist or wet.Minimize exposure to terrain traps where the consequences of a small avalanche could be serious.

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

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2