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Archived

Avalanche Forecast

Apr 2nd, 2015–Apr 3rd, 2015
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
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

Regions: Northwest Inland.

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Confidence

Good

Weather Forecast

Snow starting Thursday afternoon is expected to bring 2-5 cm by Friday morning, another 5-10 cm Friday afternoon into Saturday, before generally dry conditions prevail for Sunday. Generally light but gusty souheasterly alpine winds are expected throughout the forecast period. Daytime high freezing levels should hover around 1400 m each day.

Avalanche Summary

Reports from Wednesday are limited to just one new Size 2 natural wind slab avalanche on a northeast facing alpine slope below a ridge crest. However, reports from Tuesday include several small natural and skier triggered wind slab avalanches in lee and cross-loaded treeline and alpine terrain. The reports mentioned surprisingly little large avalanche activity given the strong winds and amount of fresh snow available for wind-transport.

Snowpack Summary

Approximately 15-30 cm of dense storm snow overlies a variety of crusty old surfaces. Recent strong winds have scoured windward slopes and loaded leeward slopes below ridgecrests and behind terrain features. Persistent weaknesses buried in the upper snowpack may include hard crusts and/or facet crystals, although not much is known about the reactivity or spatial distribution of these layers. At the base of the snowpack, weak facets may be found. Cornices are large and potentially fragile. Unpredictable, full-depth glide avalanches are also a concern on low elevation slopes with smooth ground cover (grassy slopes, rock slabs, etc.) where large cracks have formed from the snowpack slipping on the ground.

Avalanche Problems

Wind Slabs

Recently formed wind slabs may remain reactive for a few days. Watch for triggering in the lee of ridge crests and terrain breaks.
Be cautious as you transition into wind affected terrain.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>Minimize overhead exposure; avalanches triggered by windloading may reach run out zones.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4