Archived

Avalanche Forecast

Mar 22nd, 2017–Mar 23rd, 2017

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

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

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

Regions: Glacier.

We are in a tricky Low Probability, High Consequence cycle. The reality is that large, likely un-survivable avalanches will continue to occur sporadically and are very hard to predict. Manage your exposure and be conservative in terrain selection!

Weather Forecast

Unsettled weather continues. Today should be mainly cloudy, with isolated flurries and moderate S'ly winds. Freezing levels will rise to 1700m. Overnight continued flurries will accumulate to ~6cm, with mod to strong SW winds. Thurs should be dry with sunny breaks in the afternoon. Friday should be cloudy with flurries adding up to another 8cm.

Snowpack Summary

Recent storm instabilities are gaining strength. Winds have been shifting directions forming windslabs in alpine lee's and adding to the already huge cornices. Mid February PWL's are now down ~150cm and were reactive during last weeks storm. The basal weakness (Nov 13 crust) has been reactive to large triggers (ie cornices and step-downs).

Avalanche Summary

The snowpack has demonstrated it's potential to produce very destructive avalanches. For example, on Sat Macdonald West Shoulder avalanched naturally ripping out mature timber and running to the valley floor. Sporadic avalanches continue to occur, like this one in the Smart drainage on Monday, showing wide propagation and multiple step down layers.

Confidence

Avalanche Problems

Wind Slabs

With a lot of new snow available for transport and winds shifting directions, expect wind-slabs to have formed in many areas. If triggered they may step down to deeper layers. Overloaded cornices have been failing and triggering very large avalanches

Use caution in lee areas. Recent wind loading has created wind slabs.Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Persistent Slabs

It is an impressive and humbling time to be traveling in the back-country. Very large avalanches have been occurring, even logging mature timber. These large avalanches continue to occur sporadically and are very hard to predict.

Choose regroup spots that are out of avalanche terrain.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 3 - 4