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Avalanche Forecast

Mar 11th, 2016–Mar 12th, 2016
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
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: Sea To Sky.

Ongoing snowfall and strong southerly winds will keep the hazard HIGH in the alpine on Saturday.  Conservative decision making is critical and it is best to stick to mellow terrain.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The next storm front should arrive Friday evening and 15-30cm of new snowfall is expected by Saturday morning. Freezing levels are expected to drop to around 1000m and alpine winds are forecast to be strong from south. Another 10-20cm of snowfall is expected on Saturday with freezing levels around 1000m and strong alpine winds from the southwest. Light snowfall is forecast to continue on Saturday overnight and Sunday morning with another 10-20cm of snowfall possible. Periods of clearing are expected between storm pulses over the weekend but there is lots of uncertainty regarding the timing. Unsettled conditions are currently expected for Monday with light snowfall and sunny breaks both possible.

Avalanche Summary

Observations were limited on Thursday due to the stormy conditions but natural storm slab avalanches were reported up to size 2.5. Explosives also triggered numerous storm slab avalanches up to size 2.5. Slab thickness was typically 30-40cm and up to 100cm thick in wind loaded areas. Skiers triggered several small avalanches in wind loaded features and on steep or unsupported features. Loose wet sluffing was reported from lower elevations that saw rain. Storm slabs are expected to remain very touchy to human-triggering on Saturday and natural activity is possible in freshly wind loaded terrain.

Snowpack Summary

Up to 75cm of new storm snow is being reported in sheltered areas with up to 150cm in wind loaded areas. Weaknesses within or at the base of the new storm snow may need a couple days to settle and strengthen. Extreme southerly winds have created very deep and dense slabs in lee terrain, probably well below ridge crests, while scouring windward slopes. Ongoing stormy weather has also encouraged extensive cornice growth. The mid and lower snowpack are strong and well-settled.

Avalanche Problems

Storm Slabs

Widespread storm slabs are expected to be very reactive to human-triggering, especially in wind loaded terrain.
The new snow will require several days to settle and stabilize. >Avoid freshly wind loaded features. >Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Cornices

Cornices are reported to be massive and weak. These could pop off at any time, but are more likely to fail during stormy periods or during brief sunny breaks.
Extra caution needed around cornices with current conditions.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5