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Avalanche Forecast

Mar 14th, 2013–Mar 15th, 2013
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
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
3: Considerable
The avalanche danger rating at treeline will be considerable
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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Sea To Sky.

Confidence

Fair - Freezing levels are uncertain on Friday

Weather Forecast

Synopsis:  The true pineapple breaks down Friday and a more zonal flow builds in its place which opens the door to a series of weak systems. Friday:  Freezing Level 1300m.  Precip: 2-5mm Wind: Light, SESaturday:  Freezing Level 900m.  Precip: 4mm Wind: Moderate SW gusting to StrongSunday: Freezing Level 1100m in the afternoon, dropping to the surface overnight.  Trace of precip.  Wind: Light, NE

Avalanche Summary

Quite a few observations of a natural cycle to size 2.5 at upper elevations on Wednesday were received.  Both slab and loose snow avalanches were running on all aspects at the new/old snow interface down around 50 cm in depth.  It's no surprise that explosive control work in the region also produced avalanches to size 2.5 on most aspects as well. 

Snowpack Summary

The storm has delivered around 50 cm of heavy snow at upper elevations as of Thursday morning and another 15 - 25 are expected this afternoon and evening. Strong southerly winds in the alpine have created slabs on N - E facing slopes that may be up to a meter in depth.  At treeline the storm snow is a messy configuration of dry snow, moist snow, rain soaked snow and even the occasional thin crust.  As this interface cools in the coming days the ski quality may be less than premium. This new snow is bonding poorly to the previous snow surface, which includes faceted snow, surface hoar, and/or a crust, but is most concerning where surface hoar is sitting on a crust on previously sun-exposed sheltered treeline slopes. Around a metre below the snow surface is a layer surface hoar buried on February 20th. Although this layer has a history of producing large avalanches, triggering this layer has now become difficult, and would most likely require a very large trigger on a steep, unsupported slope. Below this interface, the snowpack is strong and well settled.

Avalanche Problems

Storm Slabs

Storm slabs from 40 - 100 cm in depth are present in the alpine with steep North through East facing slopes harboring the deeper slabs.  The storm will diminish Friday, but these storm slabs will likely remain sensitive to human triggering.
The new snow will require another day to settle and stabilize.>Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid large alpine features.>Large loose wet avalanches remain a concern. Limit your exposure to overhead hazard.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 6