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Avalanche Forecast

Mar 4th, 2018–Mar 5th, 2018
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
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: South Columbia.

Although the temperature is forecast to remain cool at upper elevations, when the sun does come out it can have an immediate impact on those slopes directly facing it.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

MONDAY: Mix of sun, cloud and isolated flurries / Light to moderate west wind / Alpine temperature -12 TUESDAY: Mix of sun, cloud and isolated flurries / Light west wind / Alpine temperature -13 WEDNESDAY: Mix of sun, cloud and isolated flurries / Light southwest wind / Alpine temperature -8 

Avalanche Summary

Reports through the weekend highlighted numerous natural wind and storm slab avalanches size 1.5-2.5 at treeline and in the alpine on all aspects. Additionally there were also reports of skier triggered wind and storm slab avalanches to size 1.5 as well as a remotely triggered size 1.5 persistent slab avalanche on a northwest aspect at 1300m. On Saturday there was a report of skier triggered size 1.5 persistent slab avalanche on a northeast aspect at 1500m with a 100cm fracture in the southern portion of the region.

Snowpack Summary

An additional 20-40cm of new snow fell Thursday through Saturday, bringing the storm snow total this week to 50 to 90cm. This storm snow has been redistributed into localized wind slabs. It covers old surfaces including faceted powder, a sun crust on solar aspects, and surface hoar on shady slopes. Around 70 to 110cm below the surface there's a layer buried mid-February that's a sun crust on solar aspects and spotty surface hoar on sheltered slopes. This layer looks most concerning on solar aspects where it's associated with with small facets or surface hoar. There are several deeper layers that have shown signs of improving but still remain suspect as low probability to trigger yet will result as a high consequence avalanche if triggered. We are talking about surface hoar layer buried back in December and January. Near the base of the snowpack is a November crust combined with loose sugary snow. These layers may "wake-up" with strong inputs such as sustained warming, sustained snowfall, large triggers (e.g. cornice fall, smaller avalanches coming down from above); human triggering is also possible in shallow, rocky terrain.

Avalanche Problems

Wind Slabs

Localized wind slabs may have formed on the down-wind side of ridges and ribs. Watch cross-loaded slopes and gullies too.
Use ridges or ribs to avoid pockets of wind loaded snow.Extra caution needed around cornices with current conditions.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 - 2

Persistent Slabs

A weak layer buried up to 80cm deep "woke-up" last week. This problem seems most reactive in south-facing terrain where buried crusts exist.
Watch convoluted terrain with variable or shallow snow depths and multiple trigger points.Pay attention to overhead hazards like cornices which could trigger persistent slabs.Carefully assess and consider avoiding southerly facing slopes.

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

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 3