Avalog
Register
Get forecast notifications
Create an account to receive email notifications when forecasts are published.
Register
Login
Archived

Avalanche Forecast

Apr 22nd, 2013–Apr 23rd, 2013
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
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
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: Glacier.

The Winter Permit System is no longer in effect. We are into the spring pattern; with avalanche danger increasing on solar aspects through the day. Get an early start, watch for solar warming and avoid slopes threatened by cornices overhead.

Weather Forecast

Strong solar is expected today and Tuesday. Freezing levels are expected to rise to 1700m, with temps below treeline getting above freezing. Expect crusts to break down quickly. Cool alpine temps, -10'C, will help with overnight recoveries. On Wednesday,  we should see increasing cloud as a system moves in, bringing precip and rising temps.

Snowpack Summary

Rain to 1900m turned to snow early Saturday. Above 1900m up to 20cm of snow overlies a variety of surfaces including crusts, surface hoar and moist isothermal snow. SW winds loaded lee slopes but have backed off overnight. The April 3rd crust is down around 50-60 cm. Snow below treeline is isothermal, but cool overnight temps are allowing recovery.

Avalanche Summary

Large avalanches continue to be reported. Size 2-2.5 solar triggered avalanches occurred yesterday from E and S aspects. A size 3, likely a day old, was observed on the NE face of Cougar. It propagated across most of the face, and likely failed on the March surface hoar. Last week skiers triggered a size 2.5 on N asp and size 3 on an NE aspect.

Confidence

Avalanche Problems

Storm Slabs

20cm of new snow above 1900m may bond poorly to the various surfaces below.  Storm slab avalanches occurred yesterday on slopes receiving direct sun. Solar triggered avalanches are expected with strong solar warming today.
Minimize exposure to sun exposed slopes when the solar radiation is strong.Make observations and assess conditions continually as you travel.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Wind Slabs

Moderate to strong S-SW winds have transported the new snow; forming large cornices, deep pockets and isolated windslabs on lee features. They are especially likely in the alpine where winds were highest, and may bond poorly where crusts exist.
Cornices become weak with daytime heating, so travel early on exposed slopes.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

Large avalanches failing on deeper weak layers are still being human triggered, as was demonstrated Monday. They are also sporadically occurring naturally, triggered by windloading, cornice fall and solar warming.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely

Expected Size: 2 - 3