Archived

Avalanche Forecast

Mar 17th, 2014–Mar 18th, 2014

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

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

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: Glacier.

We've had a significant amount of snow over the last few days as well as multiple buried weak layers. Approach the backcountry with caution until things have had a chance to settle.

Weather Forecast

Westerly flow will continue to bring unsettled weather to the interior throughout the week. Light snow with generally light west winds are forecast until Tuesday night when more moderate amounts of snow are expected with the arrival of the next storm. Temperatures will remain cool until then.

Snowpack Summary

15cm of low density snow overnight sits over settling storm snow. The Mar 13 crust is down ~50cm on solar aspects and below 1600m. The Mar 2 crust is down around 1m-1.25m and the Feb 10 surface hoar/crust layer is down 1.5m-2m. The mid and lower snowpack is very well settled.

Avalanche Summary

Natural avalanche cycle yesterday and artillery control produced avalanches to size 4.0 with numerous size 3-3.5 within the highway corridor. From March 13th, skiers remotely triggered this avalanche on Grizzly peak. Note the shallow, south facing start zone. It ran presumably on the March 2nd crust.

Confidence

Due to the number of field observations

Avalanche Problems

Storm Slabs

65cm has fallen over the last 4 days with strong winds yesterday. On solar aspects this has buried a thick sun crust. Venturing out into larger terrain is not a good idea at this point as this new load will need some stabilization time.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Persistent Slabs

Down around 1-1.25m is a buried crust from early March. Backcountry users have been reporting whoomphs and remotely triggering this layer prior to this latest storm. Extra caution on steep south and west slopes where the crust was well formed.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Deep Persistent Slabs

The February deep instability, down1.5m-2m will need a large trigger to be initiated. Although the sudden snow loading has ended, it may get triggered by a large cornice for or from a shallower avalanche.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4