Archived

Avalanche Forecast

Apr 20th, 2014–Apr 21st, 2014

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

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 Coastal.

Avalanche danger can rise quickly with afternoon warming and solar radiation. Be aware of changing conditions and overhead hazards.For more insight into spring danger ratings, check out this Blog Post.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Light precipitation is expected to continue on Monday. Light scattered precipitation with periods of sun is likely on Tuesday. Dry, sunny conditions are expected for Wednesday. Sun. Night/Monday: Precipitation 6-10mm, freezing level am: 800m pm: 1200m, ridgetop wind: moderate-strong STuesday: Cloudy with sunny breaks, scattered precipitation 1-3mm, freezing level am: 700m pm: 1100-1300m, ridgetop wind: light variableWednesday: Mostly sunny, convective flurries possible, freezing level am: 900m pm: 1400m, ridgetop wind: light variable

Avalanche Summary

Reports from Friday of sluffing from steep sun exposed terrain features and isolated slabs releasing from leeward features on ridgecrests. We are no longer receiving professional daily reports for the region so public observations are really appreciated right now. If you are out in the mountains, send your observations to [email protected]

Snowpack Summary

Highly variable spring conditions are being reported in the region. At lower below-treeline elevations the snowpack is typically wet and isothermal. It has not been refreezing overnight and is melting quickly. Between roughly 1000 and 1500m, the snowpack is undergoing daily melt-freeze cycles. The same conditions can be expected on sun-exposed slopes all the way to mountain-top. On higher elevation north-facing slopes, dry snow can be found. Recent strong S through W winds have scoured windward slopes and created wind slabs in leeward slopes. The early February crust/facet layer is typically down 1.5 to 2.5m. A smaller avalanche or a cornice fall may still have the potential to step down to this layer causing very large, destructive avalanches.

Avalanche Problems

Storm Slabs

Recent storm snow may have formed storm slabs in some areas. Strong SW winds have formed stiffer wind slabs in leeward features.

The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Loose Wet

Loose wet activity can be expected from steep features during periods of solar warming or rain. Isolated wet slabs may be possible under the same conditions where the recent storm snow is poorly bonded to the underlying crust.

Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2

Deep Persistent Slabs

A deeply buried persistent weak layer still has the potential to produce very large avalanches and could be triggered by heavy triggers such as cornice falls or smaller avalanches stepping-down.

There is potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 7