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Archived

Avalanche Forecast

Mar 18th, 2016–Mar 19th, 2016
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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

Regions: Little Yoho.

Simplify your terrain choices this weekend. Sunny skies Saturday will increase the danger on solar aspects and weaken cornices on lee aspects. SH

Weather Forecast

A good freeze overnight into Saturday with mainly sunny skies. Freezing levels will shoot to 2000m quickly with high solar input and a temperature inversion (warmer air aloft). Sunday may be even warmer. Light Westerly winds through the weekend.

Snowpack Summary

40-60cm of recent, dry storm snow overlies a well settled mid and lower pack. Observations are limited but we suspect there are buried sun crusts on steep E through W aspects with 60-100cm above (similar to Banff region).  Isolated thin snowpack areas have weaker facet layers, but this is not a widespread snowpack characteristic of the region.

Avalanche Summary

Avalanche control on Mts. Stephen and Dennis Friday produced avalanches to size 3, one of which slid to ground in a steep, thin snowpack area. That flight saw numerous slides to size 3 mainly along and East of the divide where the basal weak layers are more prevalent.  These were on N- NE aspects in the alpine in the last 24-48 hours.

Confidence

Freezing levels are uncertain on Saturday

Avalanche Problems

Loose Wet

Expect loose wet avalanches on solar aspects as the day heats up. These may trigger persistent slabs where buried crusts exist.

  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2

Persistent Slabs

Now that the sun is higher in the sky, buried suncrust becomes more of a problem. Presently there are several crusts buried on S through E aspects, with 50-100 cm overlying them. We do not have many observations of this currently.

  • Dig down to find and test weak layers before committing to a line.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Cornices

They are big and mean this time of the season, and as the day heats up they like to fall off. Even on their own they can have significant mass.

  • Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 2 - 3