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Archived

Avalanche Forecast

May 1st, 2014–May 2nd, 2014
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
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
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: Banff Yoho Kootenay.

No expected freeze overnight and rain below 2400m on Friday will keep the hazard elevated until freezing levels drop. SH

Weather Forecast

Rain starting tonight and freezing levels to 2400m overnight. Alpine temperatures will stay around zero overnight.Expect a mix of rain and snow Friday up to treeline with snow at upper elevations(up to 20cm). No freeze is expected overnight. Models are calling for 30-40cm at upper elevations with  freezing levels lowering by the end of the weekend.

Snowpack Summary

A weak freeze broke down quickly this morning as temperatures rose into the double digits in the alpine early in the day. Thin snowpack areas are isothermal at all elevations and aspects. Basal facets and depth hoar are waking up as the heat penetrated the snowpack.

Avalanche Summary

A widespread natural cycle to size 3.5 has been occurring over the last 24 hours. Lots of loose wet avalanches, and many slides initiating in thin areas and running to ground. One very large avalanche in the Bryant Creek area crossed 3 alpine bowls showing that the weak basal layer is very reactive during these warm conditions.

Confidence

Freezing levels are uncertain

Avalanche Problems

Deep Persistent Slabs

With little overnight freeze, the weak basal layer will be susceptible to human triggering in thin areas. Natural activity should slow down over the next 24 hours as the freezing levels slowly go down.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 3 - 4

Loose Wet

This will be most prominent at treeline and below where we expect rain to start  Thursday night into Friday below 2400m.
Watch for clues, like sluffing off of cliffs, that the snowpack is warming up.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3