Archived

Avalanche Forecast

Mar 1st, 2019–Mar 2nd, 2019

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Lizard-Flathead.

Fresh storm slabs will likely be reactive to human triggering, especially in wind loaded areas, and at upper elevations. Watch for signs of instability such as whumphing, cracking and recent avalanches.

Confidence

Moderate -

Weather Forecast

FRIDAY NIGHT - Clear periods / east winds 10-15 km/h / alpine low temperature near -27SATURDAY - Mainly sunny / east winds 10 km/h / alpine high temperature near -21SUNDAY - Sunny / northeast winds 10-20 km/h / alpine high temperature near -16MONDAY - Sunny / northeast winds, 15-30 km/h / alpine high temperature near -13

Avalanche Summary

There were reports of numerous size 1-1.5 avalanches on Friday. They were natural, human, and explosives triggered.A few natural loose snow avalanches were reported on Thursday.A few natural wind slab avalanches size 1.5-2 on northwest aspects were reported on Wednesday.On Monday, size 1 natural and human triggered wind slab avalanches were reported on all aspects at treeline and in the alpine. Last Saturday, numerous natural and explosives triggered storm slab avalanches to size 2-2.5 were reported on north and east aspects in the alpine and treeline. These avalanches were 50-100 cm deep.

Snowpack Summary

Up to 30 cm of new snow combined with winds will be forming fresh storm slabs. The new snow sits on older wind slabs at upper elevations, which will be difficult to detect now that they are buried. In sheltered areas and below treeline, the new snow sits on facets (sugary snow) surface hoar (feathery crystals) and a crust on south facing slopes.There are potentially three weak layers of surface hoar in the top 100 cm of the snowpack. One is down 30-50 cm, another is down 40-80 cm and the last one is down 80-110 cm. These layers are most prominent between 1600-1900 m.The lower portion of the snowpack is considered generally strong.

Avalanche Problems

Storm Slabs

Up to 30 cm of new snow and moderate winds will mean that storm slabs are likely widespread. These will likely be the most reactive in wind loaded areas.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered, storm or wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

Two weak layers of surface hoar may be found 60-120 cm deep in the snowpack. They are most prominent between 1600-1900 m, and have been the culprit in recent large avalanches, particularly in openings such as cutblocks, gullies, and slide paths.

Watch for signs of instability such as whumpfing, cracking, or recent avalanches.Be aware of the potential for wide propagation.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 2.5